Question: After overnight fasing, levels of glucosetranpoers reduced in

Adipocytes (Ref: Harper 28/e, p138, 171 (26/e p160, 232); Lippincott Biochem 3/e p310; Ganong23/e p320] Overnight fasting causes insulin levels to fall. This decreases the number of glucose transpoers which are insulin dependent. Insulin dependent glucose transpoers are GLUT-4, present in adipocytes, skeletal and cardiac muscles. Rest of the glucose transpoers are not insulin dependent. Harper writes-"Glucose uptake into muscle and adipose tissue is controlled by insulin, which is secreted by the B islet cells of the pancreas in response to an increased concentration of glucose in the poal blood. An early response to insulin in muscle and adipose tissue is the migration of glucose transpoer vesicles to the cell surface, exposing active glucose transpoers (GLUT 4). These insulin-sensitive tissues will only take up glucose from the blood stream to any significant extent in the presence of the hormone. As insulin secretion falls in the starved state, so the transpoers are internalized again, reducing glucose uptake" Glucose Transpoers Glucose enters cells either by facilitated diffusion or by secondary active transpo with No+ (in the intestine and kidneys) Glucose transpoers are a family of membrane proteins that are responsible for facilitated diffusion of glucose across cell membranes. They differ from and have no homology with the sodium-dependent glucose transpoers, SGLT 1 and SGLT 2, responsible for the secondary active transpo of glucose in the intestine and renal tubules. Seven different glucose transpoers, named GLUT 1-7 in order of discovery. have been characterized. Each transpoer appears to have evolved for special tasks. GLUT 4 is the transpoer in muscle and adipose tissue that is stimulated by insulin. Glucose Transpoers in Mammals Function Major Sites of Expression Facilitated diffusion GLUT 1 Basal glucose uptake Brain, kidney, colon, placenta, erythrocytes GLUT 2 B-cell glucose sensor; transpo out of intestinal and renal epithelial cells B cells of pancreatic islets, liver, small intestine, kidneys GLUT 3 Basal glucose uptake Brain, placenta, kidneys GLUT 4 Insulin-stimulated glucose uptake Skeletal and cardiac muscle, adipose tissue GLUT 5 Fructose transpo Jejunum, sperm GLUT 6 None Pseudogene GLUT 7 Glucose 6-phosphate transpoer in endoplasmic reticulurn Liver, ? other tissues Secondary active transpo (Nal? glucose cotranspo) SGLT 1 Absorption of glucose Small intestine, renal tubules SGLT 2 Absorption of glucose Renal tubules


Question: The aim of ENCODE project is

Human genome is sequenced, but needs to be annotated. Annotation is the process of identifying the function of each DNA element. ENCODE (Encyclopaedia of DNA elements) To provide a detailed, biochemically informative representation of the human genome using high-throughput sequencing methods to identify and catalogue the functional elements.

Metagenome (genome of intestinal flor) analysis

To identify the functional elements of human genome


Question: The class of amino acids that contains only non essential amino acids is


Question: Defect in collagen formation is seen in

Scurvy is caused due ti deficiecy of ascorbc acid. Ascorbic acid is necessary for the post-transltional hydroxylation of proline and lysine residues. Hyroxyproline and hydrolysine are essential for the formation of crosslinks in the collagen, which gives the tensile strength to the fibers. This process is absolutely necessary for the normal production of suppoing tissues such as osteiod, collagen and intercellular cement substance of capillaries. REFERENCE: DM VASUDEVAN SEVENTH EDITION ; PAGE NO:497


Question: Best radiolabelled marker for DNA replication is

Nucleic acids are readily labeled with tags that facilitate detection or purification. A variety of enzymatic or chemical methods are available to generate nucleic acids labeled with radioactive phosphates, fluorophores, or nucleotides modified with biotin or digoxygenin for example.


Question: Tocopherols are the derivatives of

Active vitamine E was isolated from wheat germ oil and named tocopherolA chromane ring(tocol) system with an isoprenoid side chain is present in all naturally occurring tocopherols.Vitamine K is naphthoquinone derivative with a long isoprenoid side chain.Reference: DM Vasudevan biochemistry page no: 460


Question: Ochronosis is

The metabolic defect in alkaptonuria is a defective homogentisate oxidase (EC 1.13.11.5), the enzyme that catalyzes reaction 3 of. The urine darkens on exposure to air due to oxidation of excreted homogentisate. Late in the disease, there is ahritis and connective tissue pigmentation (ochronosis) due to oxidation of homogentisate to benzoquinone acetate, which polymerizes and binds to connective tissue.Reference: Harper biochemistry, 30th edition, page no 304


Question: Vit B 12 is absorbed in

The  cobalamin-lF complex travels through the gut. The complex binds to specific receptors on the surface of the mucosal cells of the ileum. The binding of the complex and entry of B12 into the mucosal cells is mediated by Ca2+ ions. In the  mucosal  cells,  B12  is  converted  to methyf cobalamin. lt is then transported in the circulation in  a  bound form to  proteins namely  transcobalamins.


Question: The helical structure model of two polynucleotide chains of DNA was proposed by


Question: Menkes Kinky hair syndrome is characterized by congenital deficiency of

Ans. d (Copper binding ATPase) (Ref. Harper 28th/573-4; H-17th/449).Menkes disease ("kinky" or "steely" hair disease) is a disorder of copper metabolism that occurs due toMutations in the Gene Encoding a Copper-Binding P-Type ATPase.MENKES DISEASE# It is X-linked, affects only male infants, involves the nervous system, connective tissue, and vasculature, and is usually fatal in infancy.# When altered by mutation, copper is not mobilized normally from the intestine, in which it accumulates, as it does in a variety of other cells and tissues, from which it cannot exit.# Despite the accumulation of copper, the activities of many copper-dependent enzymes are decreased, perhaps be- cause of a defect of its incorporation into the apoenzymes.# Normal liver expresses very little of ATPase, which explains the absence of hepatic involvement in Menkes disease.Wilson Disease Is Also Due to Mutations in a Gene Encoding a Copper-Binding P-Type ATPase.


Question: Chitin contains

It is present in exoskeletons of crustacea and insects. It is composed of units of N-acetyl-glucosamine with beta -1,4-glycosidic linkage.Ref: DM Vasudevan, page no: 79


Question: The number of ATPs produced by HMP shunt is

The number of ATPs produced by HMP shunt is zero HMP shunt/ Pentose Phosphate pathway Neither produces nor utilizes ATPs. 2 main products of HMP shunt: NADPH - in the irreversible oxidative phase Ribose-5-phosphate - In Reversible non-oxidative phase Rate limiting enzyme - Glucose-6-phosphate dehydrogenase. Extra Edge: The pathways producing Zero ATPs are: HMP (Hexose Monophosphate Pathway) Uronic Acid Pathway Alpha Oxidation Oxidation of Very Long Chain Fatty Acids (VLCFA) RL Shunt/cycle Synthesis of Ketone Bodies


Question: Bilayer cell membrane contains

The phospholipids are arranged in bilayers with the polar head groups oriented towards the extracellular side and the cytoplasmic side with a hydrophobic core (Fig. 2.4A). The distribution of the phospholipids is such that choline-containing phospholipids are mainly in the external layer and ethanolamine and serine containing phospholipids in the inner layer. The cholesterol content of the membrane alters the fluidity of the membrane. When cholesterol concentration increases, the membrane becomes less fluid on the outer surface, but more fluid in the hydrophobic core. The effect of cholesterol on membrane fluidity is different at different temperatures. At temperature below the Tm cholesterol increases fluidity and thereby permeability of the membrane. At temperatures above the Tm, cholesterol decreases fluidity.Ref: DM Vasudevan, page no: 11


Question: Danaparoid is absent of

Danaparoid is a low molecular weight (LMW) and chondroitin sulfate. A natural


Question: Glutathione reductase assay is helpful in assessing the deficiency of


Question: Inactive precursors of enzymes are known as


Question: Protein glycosylation occurs in

Glycosylation is the reaction in which a carbohydrate, i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule. In biology, glycosylation mainly refers in paicular to the enzymatic process that attaches glycans to proteins, or other organic molecules Ref satyanarayana 4e


Question: Sulphur containing amino acid is

(A) Cysteine # Sulfur-containing amino acids (cysteine & methionine) are generally considered to be nonpolar and hydrophobic.> In fact, methionine is one of the most hydrophobic amino acids and is almost always found on the interior of proteins.> Cysteine on the other hand does ionize to yield the thiolate anion.


Question: Forbe&;s disease is due to deficiency of

Glycogen storage disease type III is an autosomal recessive metabolic disorder and inborn error of metabolism characterized by a deficiency in glycogen debranching enzymes. It is also known as Cori&;s disease in honor of the 1947 Nobel laureates Carl Cori and Gey Cori. Other names include Forbes disease in honor of clinician Gilbe Burnett Forbes (1915-2003), an American Physician who fuher described the features of the disorder, or limit dextrinosis, due to the limit dextrin-like structures in cytosol. Limit dextrin is the remaining polymer produced after hydrolysis of glycogen. Without glycogen debranching enzymes to fuher conve these branched glycogen polymers to glucose, limit dextrinosis abnormally accumulates in the cytoplasm.Ref: DM Vasudevan, 7th edition, page no: 129


Question: Glucoronide reaction is seen in


Question: Ketone bodies are formed in the

Acetoacetate is the primary ketone body while beta-hydroxybutyrate and acetone are secondary ketone bodies. They are synthesised exclusively by the liver mitochondria.Ref : DM Vasudevan - Textbook of Biochemistry 6th Edition pg no: 143


Question: In muscle, phosphorylase b is inactivated by

In muscle, glycogen phosphorylase is activated by hormones and neural signals such as epinephrine, that stimulate phosphorylase kinase which phosphorylates the Ser-14 residue of the protein. A second messenger of a cyclic AMP (cAMP) increases in concentration due to epinephrine or glucagon, and this increase results in an enzyme cascade. Activation of phosphorylase kinase is due to increased concentrations of Ca2+ or by the phosphorylation by protein kinase A which is cAMP-dependent. The activated kinase, in turn, activates the glycogen phosphorylase enzyme by phosphorylating the Ser-14 residue. In the liver, glucagon is the primary signal which catalyzes this enzyme cascade. Glycogen phosphorylase b is not always inactive in muscle, as it can be activated allosterically by AMP. An increase in AMP concentration, which occurs during strenuous exercise, signals energy demand. AMP activates glycogen phosphorylase b by changing its conformation from a tense to a relaxed form. This relaxed form has similar enzymatic propeies as the phosphorylated enzyme. An increase in ATP concentration opposes this activation by displacing AMP from the nucleotide binding site, indicating sufficient energy stores.


Question: A defect in the enzyme hexosaminidase causes

DiseaseEnzyme DeficiencyClinical SymptomsTay-Sachs disease Hexosaminidase AMental retardation, blindness, muscular weaknessRef: Harper&;s Biochemistry; 30th edition; Chapter 24 Metabolism of Acylglycerols & Sphingolipids


Question: Rapid method of chromosome identification in intersex is

Fluorescence in situ hybridization(FISH) is a cytogenetic technique that uses fluorescent probes that bind to only those pas of the chromosome with a high degree of sequence complementarity. It was developed by biomedical researchers in the early 1980s and is used to detect and localize the presence or absence of specific DNA sequences on chromosomes.


Question: Another name for glucose

Glucose is the predominant sugar in the human body. It is the major energy source. It is present in blood. -glucose is dextro- rotatory. In clinical practice , it is often called as dextrose.Ref: DM Vasudevan, 7th edition, page no: 71


Question: A bilipid layer is most permeable to

This Flip-flop movement is catalyzed by enzymes. Flippases catalyse the transfer of amino phospholipids across the membrane. Floppases catalyse the outward directed movement which is ATP dependent. This is mainly seen in the role of ABC proteins mediating the efflux of cholesterol and the extrusion of drugs from cells. The MDR (multidrug resistance) associated p-glycoprotein is a floppase. Urea is the most permeable substance across the cell membraneRef: DM Vasudevan, page no: 11


Question: Following are second messengers

Cyclic adenosine monophosphate(cAMP, cyclic AMP, or 3&;,5&;-cyclic adenosine monophosphate) is a second messenger impoant in many biological processes.cAMP is a derivative of adenosine triphosphate(ATP) and used for intracellular signal transduction in many different organisms, conveying the cAMP-dependent pathway.Ref: DM Vasudevan, 7th edition


Question: In vitamin B12 deficiency, folate is trapped in the form of

Methylation of homocysteine to methionine is the only way of regeneration of active THFA from methyl THFA. Methionine synthase reaction requires methyl cobalamin. So, deficiency of methyl-B12 leads to trapping of THFA in less utilised methyl-THFA - phenomenon known as folate trap.


Question: Tangier disease is due to deficiency of

Name Defect Remarks Familial alpha-lipoprotein deficiency Tangier disease Fish-eye disease apo-A-I deficiencies All have low or near absence of HDL Tendency toward hyperiacylglycerolemia as a result of absence of apo C-ll, causing inactive LPL. Low LDL levels. Atherosclerosis in the elderly. Reference: Harper; 30th edition; Page no: 275


Question: The following separation technique depends on the molecular size of the protein

Answer is C Size-exclusion--or gel filtration--chromatography separates proteins based on their Stokes radius, the radius of the sphere they occupy as they tumble in a solution. The stokes radius is a function of molecular mass and shape. When rapidly tumbling, an elongated protein occupies a larger effective volume than a spherical protein of the same mass. Size-exclusion chromatography employs porous beads. Ref: Harper's Illustrated Biochemistry, 30E (2015) Pg No 27. in Ion Exchanege chromatography ,Cation-exchange solid phases contain covalently bound, negatively charged functional groups. Examples include strongly acidic groups, such as sulfonate ions, or weakly acidic groups, such as carboxyl or carboxymethyl . Immobilized enzymes have been chemically bonded to adsorbents, such as (1) microcrystalline cellulose,(2) diethylaminoethyl (DEAE) cellulose, (3) carboxymethyl cellulose, and (4) agarose. Ref: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 5E Pg no 308 and 375 Iso Electric focussing is based on electric field and pH. Ionic buffers called ampholytes and an applied electric field are used to generate a pH gradient within a polyacrylamide matrix. Applied proteins migrate until they reach the region of the matrix where the pH matches their isoelectric point (pI). Ref: Harper's Illustrated Biochemistry, 30E (2015) Pg No 29.

Chromatography on a carboxymethyl cellulose column

Chromatography on a diethylaminoethyl (DEAE) cellulose column


Question: Familial hypercholesterolemia is associated with

A positive correlation exists between the incidence of atherosclerosis and the plasma concentration of LDL cholesterol. The LDL (apoB-100, E) receptor is defective in familial hypercholesterolemia, a genetic condition which blood LDL cholesterol levels are increased, causing premature atherosclerosis.Ref: Harper&;s Biochemistry; 30th edition; Chapter 25; Lipid Transpo & Storage


Question: Not obtained from plant source

Cobalamine(Vitamin B12)is synthesized only by microorganisms; it is not present in plants. Animals obtain the vitamin performed from their natural bacterial flora or by eating foods derived from other animals. Cobalamin is present in appreciable amounts in liver, whole milk, eggs, oysters, fresh shrimp, pork, and chicken. Ref: Lippincott, Textbook of Biochemistry, page no 376


Question: Frameshift mutation doesn&;t occur in multiples of

A frameshift mutation is a genetic mutation caused by a deletion or inseion in a DNA sequence that shifts the way the sequence is read. A DNA sequence is a chain of many smaller molecules called nucleotides. DNA (or RNA) nucleotide sequences are read three nucleotides at a time in units called codons, and each codon corresponds to a specific amino acid or stops signal. During translation, the sequence of codons is read in order from the nucleotide sequence to synthesize a chain of amino acids and form a protein. Frameshift mutations arise when the normal sequence of codons is disrupted by the inseion or deletion of one or more nucleotides, provided that the number of nucleotides added or removed is not a multiple of three. For instance, if just one nucleotide is deleted from the sequence, then all of the codons including and after the mutation will have a disrupted reading frame. This can result in the incorporation of many incorrect amino acids into the protein. In contrast, if three nucleotides are inseed or deleted, there will be no shift in the codon reading frame; however, there will be either one extra or one missing amino acid in the final protein. Therefore, frameshift mutations result in abnormal protein products with an incorrect amino acid sequence that can be either longer or shoer than the normal protein. Ref-Sathyanarayana 4/e p384


Question: Biological value of protein is related to

The indices are used to assess the nutritional value of proteins. Biological Value (BV) of Protein : It is the ratio between the amount of nitrogen retained and nitrogen absorbed during a specific interval. Net Protein Utilization (NPU): NPU = Retained nitrogen / intake of nitrogen x 100 Net Dietary Protein Value (NDPV): This will assess both quantity and quality of the proteins in the diet. NDPV = Intake of N x 6.25 x NPU Protein Efficiency Ratio (PER) It is the weight gain per gram of protein taken. The essential amino acid content can also be expressed in terms of chemical score (mg of amino acid per gram of protein). Ref: Textbook of Biochemistry for Medical Students, 7E (DM Vasudevan)(2013) Pg no 533-534.


Question: The hanup disease causes the deficiency of

Pellagra is caused by the deficiency of tryptophan and niacin. Pellagra is characterized by photosensitive dermatitis. As the condition progresses, there is dementia and possibly diarrhea. Untreated pellagra is fatal. Although the nutritional etiology of pellagra is well established, and either tryptophan or niacin prevents or cures the disease, additional factors, including deficiency of riboflavin or vitamin B6, both of which are required for synthesis of nicotinamide from tryptophan, may be impoant. A number of genetic diseases that result in defects of tryptophan metabolism are associated with the development of pellagra, despite an apparently adequate intake of both tryptophan and niacin. Hanup disease is a rare genetic condition in which there is a defect of the membrane transpo mechanism for tryptophan, resulting in large losses as a result of intestinal malabsorption and failure of renal reabsorption. In carcinoid syndrome, there is a metastasis of a primary liver tumor of enterochromaffin cells, which synthesize 5-hydroxytryptamine. Overproduction of 5-hydroxytryptamine may account for as much as 60% of the body's tryptophan metabolism, causing pellagra because of the diversion away from NAD synthesis. Reference: Harper; 30th edition; Page no: 557


Question: In chromatography, mass movements of the substances are due to

In chromatography, mass transfer refers to the movement of a solute through the mobile or stationary phases, i.e. net mass transfer of the solute from one phase to the other.
Transfer of solute through a specific phase is by diffusion and is concentration driven according to Fick's law.


Question: The heme prosthetic group is found in

Myoglobin is a monomeric protein that acts as a secondary oxygen transporter and binder in the muscle tissues.
Furthermore, the tertiary feature of myoglobin resembles water-soluble globule protein characteristics.
The diffusion and use of oxygen in the muscles are necessary for the bodily system processes such as respiration.
Myoglobin has 8 right-handed a-helices separately forming a polypeptide chain and each contains a single heme prosthetic group with a central bound iron atom.


Question: The first gene therapy (somatic enzyme) was successfully done in

Deficiency of adenosine deaminase, a condition that affects lymphocytes paicularly, was the first disease to be treated by gene therapy. Deficiency of adenosine deaminase accounts for 15% of all cases of severe combined immunodeficiency (SCID)In 1990, Dr. William French Anderson introduced a new copy the gene, carried on a retroviral vector, into a 4-year-old girl suffering from severe combined immunodeficiency (Bubble boy disease).Ref: Harper 30th edition pg: 699


Question: Receptor mediated endocytosis is by

Ans is A i.e. Clathrin EndocytosisThe process by which cells take up large molecules is called endocytosis.Endocytotic vesicles are generated when segments of the plasma membrane invaginate, enclosing a minute volume of extracellular fluid and its contents. The vesicle then pinches off as the fusion of plasma membranes seals the neck of the vesicle at the original site of invagination.* There are two general types of endocytosis:PhagocytosisPinocytosisPha2ocvtosisinvolves ingestion of large particles such as viruses, bacteria, cells or debris.Phagocytosis occurs only in specialized cells such as macrophages and granulocytes.PinocytosisIt is a property of all cellsIt is cellular uptake of fluid and fluid contents.Pinocytosis is of two types :Fluid phase pinocytosis - is a non-selective process in which the uptake of a solute is simply proportionate to its concentration in the surrounding extracellular fluid:Absorptive pinocytosis: is a receptor mediated selective process primarily responsible for the uptake of macromolecules. The vesicles formed during absorptive pinocytosis are derived from invagination (pits) that are coated on the cytoplasmic side with a filamentous material. In many systems, clathrin is the filamentous material. For .e.g LDL is internalized by means of coated pits containing the LDL receptors.


Question: The sugar found in RNA is

Ribose is a constituent of RNA. Ribose is also seen in co-enzymes such as ATP and NAD. Deoxyribose is seen in DNA.
Reference: Vasudevan 7th  ed, pg 76


Question: Serotonin is a derivative of

(A) Tryptophan # SEROTONIN (5-hydroxytryptamine, 5 HT), produced from tryptophan is important in mere impulse transmission (neurotransmitter)> It regulates sleep, behaviour, blood pressure etc.> Hydroxylation of tryptophan to 5-hydroxytryptophan is catalyzed by liver tyrosine hydroxylase.> Subsequent decarboxylation forms serotonin (5-hydroxytryptamine), a potent vasoconstrictor and stimulator of smooth muscle contraction.> Catabolism of serotonin is initiated by monoamine oxidase (MAO) catalyzed oxidative deamination to 5-hydroxindoleacetate, which humans excrete in their urine (2-8 mg/d)> The psychic stimulation that follows administration of iproniazid is attributed to its ability to prolong the action monoamine oxidase> Serotonin or 5-hydroxytryptamine (5 HT) is a neurotransmitter, synthesized from tryptophan.> Normally, about 1 % of tryptophan is converted to serotonin> The production of 5HT occurs in the target tissues.


Question: Total number of genes in a human being is

Current estimates suggest that there are 25,000 protein-coding genes in humans. This implies that most of the DNA is non-protein-coding, i.e. its information is never translated into an amino acid sequence of a protein molecule.


Question: Primary Hyperoxaluria occurs due to defect in metabolism of

Glycine is the amino acid that has a single hydrogen atom as its side chain. It is the simplest possible amino acid. The chemical formula of glycine is NH2‐CH2‐COOH. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (GGU, GGC, GGA, GGG).
Glycine is a colorless, sweet-tasting crystalline solid. It is the only achiral proteinogenic amino acid. It can fit into hydrophilic or hydrophobic environments, due to its minimal side chain of only one hydrogen atom. The acyl radical is glycyl


Question: The two nitrogen atoms, that are incorporated into the urea cycle. The source of the nitrogen are

(Aspartate & NH3) (448 - R S 7th) (251 - Lippincott's)UREA CYCLE* One nitrogen of the urea molecule is supplied by free NH3 and other nitrogen by aspartate* Glutamate is the immediate precursor of both ammonia through oxidative deamination by glutamate dehydrogenase) and aspartate nitrogen (through transmination of oxaloacetate by aspartate aminotransferase* Urea is produced by the hydrolysis of arginine* The urea cycle is linked to the TCA cycle through the production of fumarate. Amino acid catabolism is therefore directly coupled to energy production


Question: One of the following is an example of phosphoprotein

The phosphate groups add negative charges to the polypeptides. The functional significance of this modification varies from one protein to the next. For example, the milk protein casein has many phosphoserine groups that bind Ca2+. Calcium, phosphate, and amino acids are all valuable to suckling young, so casein efficiently provides three essential nutrients. And as we have seen in numerous instances, phosphorylation dephosphorylation cycles regulate the activity of many enzymes and regulatory proteins. Ref: Lehninger's Principles of Biochemistry 7th Editoin - D L Nelson, Cox Lehninger - W H Freeman Pg no 2901 Ref: Lehninger's Principles of Biochemistry 4th Editoin - D L Nelson, Cox Lehninger - W H Freeman Pg no 1063.


Question: Type IV complex of ETC is inhibited by

Cyanide is probably the most potent inhibitor of ETC (Complex IV). It binds to Fe3+ of cytochrome oxidase blocking mitochondrial respiration leading to cell death. Cyanide poisoning causes death due to tissue asphyxia (mostly of the central nervous system) In Acute cyanide poisoning Amyl nitrite is given followed by sodium thiosulphate. This is an example of Chemical antagonism i.e. one drug binding to other making it unavailable in body.


Question: DNA Amplification is done in

PCR is an in-vitro DNA amplification procedure in which millions of copies of pariticular sequence of DNA can br produced within a few hoursTwo DNA primers about 20-30 nucleotides with complementary sequence of the flanking region can be synthesized

NASBA (Nucleic acid sequential based amplification)


Question: Active form of vitamin D is

Ans. b (1,25,dihydroxy cholecalciferol). (Ref. Harrison's 17th Chapter 346; Ganong 21st/pg.392).*D2 = ergocalciferol, consumed in milk.*D3 = cholecalciferol, formed in sun-exposed skin.*25-OH D3 = storage form.*1,25 (OH)2 D3 (calcitriol) = active form.VITAMIN D# 1, 25, dihydroxy cholecalciferol is active form of vit D formed from 25hydroxy cholecalciferol in PCT.# Since it is a steriod, it acts via receptors (steroid receptor superfamily).# The mRNAs are produced in response to 1, 25 dihydroxy cholecalciferol diacetate formation of family of calbindinD proteins found in intestine, brain and kidneys, which facilitates Ca++ movement across intestine and Ca++ is absorbed. In addition it also facilitates Ca++ reabsorption in kidneys, increases synthetic activity of osteoblasts and is must for normal calcification of matrix.# Vitamin D is synthesized in skin in response to UV radiation and is also absorbed from the diet.# It is then transported to the liver, where it undergoes 25-hydroxylation.# This metabolite is the major circulating form of vitamin D.# The final step in hormone activation, la-hydroxylation, occurs in the kidney.# A reduction in serum calcium below ~2.2 mmol/L (8.8 mg/dL) prompts a proportional increase in the secretion of parathyroid hormone (PTH) and so mobilizes additional calcium from the bone.# PTH promotes synthesis of l,25(OH)2D in the kidney, which, in turn, stimulates the mobilization of calcium from bone and intestine and regulates synthesis of PTH by negative feedback.# The most specific screening test for vitamin D deficiency is a serum 25(OH)D level.


Question: The amino acid residue having an imino side chain is

Proline has pyrrolidine group in which imino group is there.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 26


Question: Natural uncoupler is

The uncoupling of oxidative phosphorylation is useful biologically. In hibernating animals and in newborn human infants, the liberation of heat energy is required to maintain body temperature. In Brown adipose tissue, thermogenesis is achieved by this process. Thermogenin, a protein present in the inner mitochondrial membrane of adipocytes, provides an alternate pathway for protons. It is one of the uncoupling proteins (UCP). Thyroxine is also known to act as a physiological uncoupler.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 234


Question: The most abundant nucleotide in body is

NUCLEOSIDE TRIPHOSPHATE: Corresponding nucleoside di- and tri-phosphates are formed by esterification of fuher phosphate groups to the existing ons. Nucleside diphosphate contains one high energy bond and triphosphates have 2 high energy bonds.ATP is the UNIVERSAL ENERGY CURRENCY. It is formed during oxidative processes by trapping the released energy in the high energy phosphate bond. REF :DM VASUDEVAN TEXTBOOK , 7TH EDITION ; Page no :562.


Question: Vitamin B12 absorption occurs in

Vitamin B12 is absorbed bound to intrinsic factor, a small glycoprotein secreted by the parietal cells of the gastric mucosa. Gastric acid and pepsin release the vitamin from protein binding in food and make it available to bind to cobalophilin, a binding protein secreted in the saliva. In the duodenum, cobalophilin is hydrolyzed, releasing the vitamin for binding to intrinsic factor. Pancreatic insufficiency can, therefore, be a factor in the development of vitamin B12 deficiency, resulting in the excretion of cobalophilin-bound vitamin B12. Intrinsic factor binds only the active vitamin B12 vitamers and not other corrinoids. Vitamin B12 is absorbed from the distal third of the ileum receptors that bind the intrinsic factor-vitamin B12 complex, but not the free intrinsic factor or free vitamin. There is considerable enterohepatic circulation of vitamin B12, with excretion in the bile, then reabsorption after binding to intrinsic factor in the ileum. Reference: Harper; 30th edition; Page no: 558


Question:
Patient with deficiency of Vitamin K, pre surgical
test required is


Question: Hypertension and heart disease.

The plaque in the renal artery causes the release of renin, which elevates aldosterone, thus raising blood pressure. Atherosclerotic plaques are also probably the cause of the heart disease. PRL (milk production), GH, or cortisol release will not lead to hypertension and heart disease.

Elevated blood levels of aldosterone and renin resulting from an atherosclerotic plaque in a renal artery.

Hyperprolactinemia due to a pituitary tumor.

Acromegaly due to a GH-producing tumor that developed in adulthood.

Cushing syndrome due to an adrenal tumor.


Question: Role of somatotropine in fat metabolism

Growth Hormone (GH) - i. It is also called somatotropin. It is a single polypeptide chain with 191 amino acids. GH is synthesized by acidophils (somatotropic cells) of anterior pituitary. ii. Plasma concentration of GH is less than 2 ng/ml during day time, with secretory peak appearing 3 hr after meals. Maximum level of GH is seen during deep sleep. For measurement of serum GH, the samples are collected during sleep and also during waking hours to assess the circadian rhythm. iii. GH secretion is regulated by the balance between GHRH and GHIH (somatostatin). The regulation of secretion is predominantly inhibitory. Hypoglycemia stimulates GH secretion, and hyperglycemia suppresses it. The hypothalamic growth hormone releasing hormone (GHRH) stimulates GH synthesis and release. Ghrelin, a peptide derived from stomach induces GHRH and directly stimulates the release of GH. Somatostatin synthesized in the hypothalamus inhibits the GH secretion. iv. The metabolic effect of GH is paly mediated by somatomedin, also known as insulin-like growth factor1 (IGF-1). The growth of long bones is stimulated by this factor. IGF-1, the peripheral target hormone of GH exes feedback inhibition. v. GH increases the uptake of amino acids by cells; enhances protein synthesis, and produces positive nitrogen balance . The anti-insulin effect of GH causes lipolysis and hyperglycemia. The overall effect of GH is to stimulate growth of soft tissues, cailage and bone. It is anabolic. vi. Excess secretion by GH secreting tumor, leads to gigantism in children and acromegaly in adults. REF:DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY, SIXTH EDITION, PG.NO.,530.


Question: Splicing Activity is a functions of

Sn-RNA is involved in RNA splicing.
Sno-RNA → r-RNA modification
mi-RNA & St-RNA → Regulation of gene expression
 SP-RNA → RNA-interference (RNA i)


Question: Metachromatic leukodystrophy is due to deficiency of

DiseaseEnzyme deficiencySymptomsMetachromaticleukodystrophyArylsulfatase AMental retardation and psychologic disturbances in adults; demyelinationRef: Harper&;s Biochemistry; 30th edition; Chapter 24 Metabolism of Acylglycerols & Sphingolipids


Question: Most abundant amino acids found in collagen;

Most abundant amino acids found in collagen is Glycine Collagen is the most abundant of all human proteins. Around 28 types of collagen are known. Type 1 is most abundant The fold in collagen is because of presence of Glycine. ADDITIONAL READING ON STRUCTURE OF COLLAGEN: Collagen is made up of 3 alpha- chains (not alpha helix). These 3 chains together make a superhelix --> Tropocollagen (a rope like triple helix) Superhelix (right-handed) is oured by Glycine residues. Glycine has the smallest side chain so it fits into the restricted space where three chains of helix come together.


Question: RNA dependent DNA polymerase is

Ans. is 'c' i.e., Reverse transcriptaseReverse transcriptase is an RNA dependent DNA polymerase that produces ds DNA from RNA template. It moves along the template in 3' 5' direction, synthesizing DNA is 5' -> 3' direction.It is seen in retro viruses (e.g. HIV).


Question: Keratinising metaplasia of salivary glands results due to deficiency of

Vitamin A deficiency produces keratinizing metaplasia of the normally columnar ductal epithelium in the major and minor salivary glands.
Ref : Handbook of Experimental  Stomatology,edited by Samuel Dreizen, Barnet M. Levy.


Question: CoA requires

The coenzyme A is a complex molecule containing B complex vitamin pantothenic acid and a molecule of beta mercapto ethanolamine; this SH group forms thioester bond in acyl-acyl coA . To emphasize the function of the SH group, the CoA is sometimes written as CoA-SHRef: DM Vasudevan, Page no: 131


Question: Gout is a disorder of

Disorders of purine metabolism :

Gout, Lesch-Nyhan syndrome, adenosine deaminase deficiency, purine nucleoside phosphorylase deficiency.

Disorders of pyrimidine metabolism :

Orotic aciduria, P-hydroxybutyric aciduria, uraciluria-thyminuria.


Question: Major apolipoprotein of chylomicrons is

One or more apolipoproteins (proteins or polypeptides) are present in each lipoprotein. They are usually abbreted as apo followed by the letter A, B, C, etc. Some apolipoproteins are integral and cannot be removed (eg, apo B), whereas others are bound to the surface and are free to transfer to other lipoproteins, eg, apos C and E). The major apolipoproteins of HDL (a-lipoprotein) are apoAs. The main apolipoprotein of LDL (b-lipoprotein) is apo B (B-100), which is found also in VLDL. Chylomicrons contain a truncated form of apo B (B-48) that is synthesized in the intestine, while B-100 is synthesized in the liver.Ref: Harper&;s Biochemistry; 30th edition; Chapter 25; Lipid Transpo & Storage


Question: Skeletal muscle is deficient in

Muscle will not release glucose into the bloodstream, because muscle tissue does not contain the glucose-6-phosphatase.Ref: DM Vasudevan, 7th edition, page no: 125


Question: Histidine load test is done for


Question: Senescent cells are deficient in

Telomeres serve to camouflage chromosome ends from the DNA damage response machinery. Telomerase activity is required to maintain telomeres. One consequence of telomere dysfunction is cellular senescence, a permanent growth arrest state. We review the key regulators of cellular senescence and recent in vivo evidence which suppos p53-dependent senescence induced by sho telomeres as a potent tumor suppressor pathway. The in vivo link between cellular senescence and tumor regression is also discussed. The relationship between sho telomere length and aging or disease states in various cells of the body is increasingly repoed Ref-Sathyanarayana 4/e


Question: Main lipid component of chylomicrons is

Plasma lipids consist of triacylglycerols (16%), phospholipids (30%), cholesterol (14%), and cholesteryl esters (36%) and a much smaller fraction of unesterified long-chain fatty acids (free fatty acids or FFA) (4%). The FFA is metabolically the most active of the plasma lipids. Lipoprotein Source Main Lipid Components Apolipoproteins Chylomicrons Intestine Triacylglycerol A-I, A-II,A-IV, B-48, C-I, C-II, C-III, E Chylomicron remnants Chylomicrons Triacylglycerol, phospholipids, cholesterol B-48, E VLDL Liver (intestine) Triacylglycerol B-100, C-I, C-II, C-III IDL VLDL Triacylglycerol, Cholesterol B-100, E LDL VLDL Cholesterol B-100 HDL Liver, intestine, VLDL, chylomicrons Phospholipids, cholesterol A-I, A-II, A-IV, C-I, C-II, C-III, D, E Albumin/free fatty acids Adipose tissue Free fatty acids Reference: Harper; 30th edition; Page no: 254


Question: Cori’s cycle is another name for

It is a process in which glucose is converted to lactate in the muscle; and in the liver this lactate is re-converted into glucose.
Reference: Vasudevan 7th  ed, pg 114


Question: Gene duplication plays an impoant role in the evolution of aEUR'

mRNA (most likely) Gene duplications are impoant forces of genome evolution which change genome size and lead to the evolution of new gene functions. Gene duplication (or chromosomal duplication or gene amplification) is any duplication of a region of DNA that contains a gene; it may occur as an error inhomologous recombination, a retrotransposition event, or duplication of an entire chromosome. The second copy of the gene is often free from selective pressure-- that is, mutations of it have no deleterious effects to its host organism. Thus it accumulates mutations faster than a functional single-copy gene, over generations of organisms. This freedom from consequences allows for the mutation of novel genes that could potentially increase the fitness of the organism or code for a new function. The two genes that exist after a gene duplication event are called paralogs and usually code for proteins with a similar function and/or structure. By contrast, ohologous genes are ones which code for proteins with similar functions but exist in different species


Question: Larger DNA segments can be cloned in

Hybrid DNA molecules can be constructed in cloning vectors typically using bacterial plasmids, phages, or cosmids. A clone is a large population of identical molecules, bacteria, or cells that arise from a common ancestor. Molecular cloning allows for the production of a large number of identical DNA molecules, which can then be characterized or used for other purposes. Cloning capacities of vectors Plasmid 0.01-10 kb Lambda phage 10-20 kb Cosmids 35-50 kb Bacterial aificial chromosome 50-250 kb Yeast aificial chromosome 500-3000 kb


Question: Protein that initiates synthesis of RNA primers

Classes of Proteins Involved in Replication Protein Function DNA polymerases Deoxynucleotide polymerization Helicases ATP -driven processive unwinding of DNA Topoisomerases Relieve torsional strain that results from helicase-induced unwinding DNA primase Initiates synthesis of RNA primers Single-strand binding proteins (SSBs) Prevent premature reannealing of dsDNA DNA ligase Seals the single strand nick between the nascent chain and Okazaki fragments on lagging strand Harper30e pg: 378


Question: GLUT2 receptors

GLUT 2 is the transpoer in liver cellsGLUT 2 has to be insulin independent since unless glucose enters beta cells GLUT 2 it won&;t be able to make the ATP required to close the K+ channel which is required to depolarize the membrane for Ca+ channels to open and Ca+ to enter the cell to bring about insulin releaseRef: DM Vasudevan, 7th edition, page no: 108


Question: Primase activity is present in

DNA polymerase alpha also known as Pol a is an enzyme complex found in eukaryotes that is involved in initiation of DNA replication Comparison of Prokaryotic and Eukaryotic DNA Polymerases (see treasure)


Question: Elongation arrest occurs due to


Question: At isoelectric pH protein

Proteins are least soluble at their isoelectric pH . Significance of isoelectric proteind : The amonoacid composition will determine the isoelectric pH of protein . The alpha amino acids and carboxyl group are utilized for peptide bond formation, and hence are not ionizable.All other ionizable groups present in the protein will influence pl of the protein. At the isoelectric point,the number of anioins andcations present on the protein molecule will be equal and the net charge is zero. At the pl value,the proteins will not migrate in an electrical field.At the pl, solubility,buffering capacity and viscosity will be minimum; and precipatation will be maximum. On the acidic side of pl, the proteins are cations and on alkaline side, they are anions in nature. REFERENCE : DM VASUDEVAN TEXTBOOK SEVENTH EDITION ; PAGE NO :41


Question: Patient present with skin bullae on the sun exposure. The defect is of

A pair of abnormally chemically bonded adjacent thymine bases in DNA, resulting from damage by ultra-violet irradiation. The cellular processes that repair this lesion often make errors that create mutations.


Question: Collagen paicularly seen in corneal epithelium is

Type X is present in many tissues but paicularly seen in the corneal epithelium Reference: Harper; 30th edition; Page no: 628 Table no: 50-1


Question: Electron transpo chain is present in

The Mitochondrial matrix is enclosed by a double membrane. The outer membrane is permeable to most metabolites and the inner membrane is selectively permeable. The outer membrane is characterized by the presence of various enzymes, including acyl-CoA synthetase and glycerophosphate acyltransferase. Other enzymes, including adenylyl kinase and creatine kinase, are found in the intermembrane space. The phospholipid cardiolipin is concentrated in the inner membrane together with the enzymes of the respiratory chain, ATP synthase, and various membrane transpoers. Reference: Harper; 30th edition; Page no: 127


Question: TATA box is seen in

TATA box (also called the Goldberg-Hogness box) is a DNA sequence (cis-regulatory element) found in the promoter region of genes in archaea and eukaryotes Ref-D.M.Vasudevan 7/e p558


Question: In Gaucher&;s disease, there is a deficiency of

Due to deficiency of glucocerebrosidase, causes glucosylceramide accumulation in macrophages called Gaucher&;s cells.DiseaseEnzyme DeficiencyClinical SymptomsGaucher diseaseb-GlucosidaseEnlarged liver and spleen, erosion of long bones,mental retardation in infantsRef: Harper&;s biochemistry; 30th edition; Chapter 24 Metabolism of Acylglycerols & Sphingolipids


Question: Increased level lipoprotein A predisposes to

Familial lipoprotein(a) excess leads premature coronary hea disease due to atherosclerosis, plus thrombosis due to inhibition of fibrinolysis.Ref: Harper 30th edition pg: 275


Question: Triplex DNA is clue to

Triple- stranded DNA- forms hydrogen bonds with another surface of the double helix through called Hoogsteenpairs.


Question: Primary link between citric acid cycle and urea cycle with

(Fumarate): (340-U.Satyanarayan 3rd) (145-Harper 28th)Integration between Urea cycle and Citric acid cycleUrea cycle is linked with citric acid cycle (TCA cycle) in three different ways. This is regarded as bicyclic integration between the two cycle1. The production of fumarate in urea cycle is the most important integrating point with TCA cycle fumarate is converted to malate and then to oxaloacetate in TCA cycle. Oxaloacetate undergoes transamination to produce aspartate which enters urea cycle. Here it combines with citrulline to produce arginosuccinate. Oxaloacetate is an important metabolite which can combine with acetyl COA to form citrate and get finally oxidized. Oxaloacetate can also serve as precursor for the synthesis of glucose (gluconeogenesis)2. ATP (12) are generated in the TCA cycle while ATP (4) are utilized for the urea synthesis3. Citric acid cycle is an important metabolic pathway for the complete oxidation of various metabolites to CO2 and H2O. The CO2 liberated in TCA cycle (in the mitochondria) can be utilized in urea cycle.


Question: Carnosine is a major constituent of

Carnosine (α-alanyl-histidine) is a dipeptide that is present in large quantities in muscle tissue.


Question: A buffer that is most effective at a pH of about 4.5 is;

Ans. is 'a' i.e. Acetate BufferRef Guyton, 10/e, p349A buffer system is most effective when the pH of the system is near its pka valueLet's see the pka of the buffers given in the questionBufferPkaPhosphateBicarbonateAcetateTris 6.8 6.14.76 (Harper 25th/e p24) 8.3 (Harper 25th/ep23)* It's the acetate buffer which has its pka (4.76) value nearest to the pH of the system (4.5), hence it will be most effective at this pH.


Question: Proteins targeted for destruction in eukaryotes are covalently linked to

(D) Ubiquitin # UBIQUITIN is a small protein present in eukaryotic cells, that targets many intracellular proteins for degradation, mainly Abnormal newly produced proteins Aged normal proteins> The 'C terminal residue of ubiquitin becomes covalently attached to lysine residues of proteins that are then degraded via an adenosine triphosphate dependent process.# Other options:> Clathrin: Clathrin is a peripheral membrane protein that helps in endocytosis. The vesicles formed during absorptive pinocytosis are derived from invaginations (pits) that are coated on the cytoplasmic site with a filamentous material known as clathrin.> Pepsin: Is a proteolytic enzyme secreted by chief cells of stomach It is used for digestion> Laminin: Is found in extracellular matrix It is the most abundant glycoprotein present in basement membrane


Question: Dietary fibre contain

Dietary fibre contains remnants of plant cells resistant to hydrolysis by the enzymes of alimentary canal. Fibre is basically composed of 2 categories : 1. Water insoluble components. 2 . Warer soluble components. 1. Water insoluble : Cellulose, Hemicellulose, Lignin 2. Water soluble : Pectins, Mucilagesn, Gums.


Question: The ability of amino acids/proteins to behave like zwitterions forms the basis for separating them using the following technique

Isoelectric focusing is based on the isoelectric pH (pH at which a molecule carries no net charge). pH gradients created in the gel using polyampholytes. As there is no net charge, molecule stops moving during electrophoresis if they encounter their pI.

Classification and metabolism of amino acids


Question: The number of molecules of ATP produced by the total oxidation of acetyl CoA in TCA cycle is

There are 3 NADH molecules generated during one cycle, each of them will give rise to 2 ½ ATPs on oxidation by electron transport chain (ETC); so altogether they will give 3 × 2 ½ = 7 ½ (7.5) high energy phosphates. The FADH2 will generate 1½ molecules of ATP. In addition, one molecule of GTP (equivalent to one molecule of ATP) is formed by substrate level phosphorylation. Hence, per turn of the cycle, 10 high energy phosphates are produced.
Reference: Vasudevan 7th  ed, pg 250


Question: The uptake of glucose by the liver increases following a carbohydrate meal because

There is increase in phosphorylation of glucose by glucokinase

Hexokinase in liver has a high affinity for glucose


Question: Malonate competitively inhibits

Inhibitors of TCA Cycle - A. Aconitase (citrate to aconitate) is inhibited by fluoro-acetate. This is non-competitive inhibition. B. Alpha ketoglutarate dehydrogenase (alpha ketoglutarate to succinyl CoA) is inhibited by Arsenite. This again is non-competitive inhibition. C. Succinate dehydrogenase (succinate to fumarate) is inhibited by malonate; this is competitive inhibition. competitive inhibition - In competitive inhibition, the inhibitor will be a structural analog of the substrate. There will be similarity in three dimensional structure between substrate (S) and inhibitor (I). For example, the succinate dehydrogenase reaction is inhibited by malonate. Competitive inhibition is usually reversible. Or, excess substrate abolishes the inhibition. REF:DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY,EIGHTH EDITION,PG.NO.,309,63.


Question: Increased intake of PUFA causes increased requirement of the following vitamin

Metabolism of Vitamin E Normal blood level of tocopherol is 0.5-1 mg/dl. It is absorbed along with other fats and needs the help of bile salts. Tocopherol is absorbed and transpoed as chylomicrons. It is stored in adipose tissue. During catabolism, the chromane ring and side chain may be oxidized and excreted in bile after conjugation with glucuronic acid.Biochemical Role of Vitamin E i. Vitamin E is the most powerful natural antioxidant (Chapter 20). Free radicals are continuously being generated in living systems. Their prompt inactivation is of great impoance. Vitamin E is a known biological antioxidant able to quench the lipid peroxidation chain and to protect the plasma membranes from the attack of free radicals.ii.The free radicals would attack bio-membranes. Vitamin E protects RBC from hemolysis. By preventing the peroxidation, it keeps the structural and functional integrity of all cells. iii. Gradual deterioration of aging process is due to the cumulative effects of free radicals. Vitamin E also boosts immune response. Fig. 33.13. Atherosclerotic plaque in a blood vessel is shown in the left side. It may be prevented by vegetables containing vitamin E iv. It reduces the risk of atherosclerosis by reducing oxidation of LDL (Fig. 33.13; see Chapter 25 for Atherosclerosis).v.Vitamin E can depress leukocyte oxidative bactericidal activity.Ref: DM Vasudevan - Textbook of Biochemistry for Medical Students, 7th edition, page no: 473


Question: Dihydrouridine is found in

Dihydrouridine (abbreted as D, DHU, or UH2) is a pyrimidine which is the result of adding two hydrogen atoms to a uridine, making it a fully saturated pyrimidine ring with no remaining double bonds. D is found in tRNA and rRNA molecules as a nucleoside; the corresponding nucleobase is 5,6-dihydrouracil Ref- Sathyanarayana 4/e


Question: Epinephrine is synthesized from norepinephrine by

Norepinephrine can be conveed into epinephrine by the enzyme phenylethanolamine N-methyltransferase with S-adenosyl-L-methionine as cofactor.


Question: Cytochrome oxidase contains

(CU) (76 - Lippincott's) (104 - HP 27th)Cytochrome oxidase (cytochroe a + a3) contains bound copper atoms, that are required for this complex reaction to occur


Question: Thiamine deficiency causes decreased energyproduction because

It is co-enzyme for pyruvate dehydrogenase Thiamine has a central role in energy-yielding metabolism and especially the metabolism of carbohydrates. Thiamine diphosphate is the coenzyme for: A) 3 multi-enzyme complexes that catalyzes oxidative decarboxylation reactions. - pyruvate dehydrogenase complex (catalyzes oxidative decarboxylation of pyruvate to acetyl-CoA) - a-ketoglutarate dehydrogenase in the citric acid cycle and - branched chain keto-acid dehydrogenase involved in the metabolism of leucine, isoleucine and valise. B) Transketolase, in the pentose phosphate pathway. The oxidative decarboxylation of pyruvate and a-ketoglutarate play a key role in energy metabolism of most cells. In thiamine deficiency, the activity of these two dehydrogenase reactions is decreased,, resulting in a decreased production of ATP.

It is required for the process of transamination

It is co-enzyme for transketolase in pentose phosphate pathway


Question: Tertiary structure of a protein describes

Secondary structure denotes the configurational relationship between residues which are about 3–4 amino acids apart; or secondary level defines the organization at immediate vicinity of amino acids.
The tertiary structure denotes three dimensional structure of the whole protein.

Reference: Vasudevan 7th  ed, pg 38


Question: RNA can is detected by

Nohern blot: A method for transferring RNA from an agarose or polyacrylamide gel to a nitrocellulose or nylon filter, upon which the RNA can be detected by a suitable probe by base-specific hybridization.Southern blot: A method for transferring DNA from an agarose gel to nitrocellulose filter, on which the DNA can be detected by a suitable probe (eg, complementary DNA or RNA).Western blot: A method for transferring protein to a nitrocellulose filter, on which the protein can be detected by a suitable probe (eg, an antibody).Southwestern blot: A method for detecting protein-DNA interactions by applying a labeled DNA probe to a transfer membrane that contains a renatured protein.Ref: Harper 30e, Page no: 469


Question: Familial hypercholesterolemia is due to defect in

Name Defect Remarks Familial hypercholesterolemia (type IIa) Defective LDL receptors or mutation in the ligand region of apo B-100 Elevated LDL levels and hypercholesterolemia, resulting in atherosclerosis and coronary disease Reference: Harper; 30th edition; Page no: 275


Question: Fatty acid synthase complex result in formation of

Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 136-138


Question: Conversion of glycine to serine requires

Conversion of glycine to serine require folic acid. From serine, The beta carbon of serine is channelled into the one-carbon pool, carried by THFA (tetrahydro folic acid). The alpha carbon of serine becomes the alpha carbon of glycine. Serine is the most impoant source of One-Carbon units Serine Hydroxy Methyl Transferase is the enzyme involved in this pathway. Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 475


Question: FIGLU is an intermediate in

Histidine metabolised to formimino glutamic acid(figlu)Ref: Textbook of biochemistry for medical students, seventh edition, page no: 243


Question: Cysteine is formed from

Serin+Homocystein ------->Cysteine+Homoserin.Homocystein is synthesized from Methionine.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 217, Fig no 16.15


Question: Guanidine group is present in

Amino acid
Special group

Histidine

Imidazole

Proline

Imino group / Pyrrolidine group

Tryptophan

Indole

ariginine

Guanidine group

Phenylalanine

Benzene ring

Tyrosine

Phenol.


Question: Antibiotic abuse can induce the deficiency of the following vitamin

Clinical deficiency of vitamin K has usually been associated with some defect in absorption from the gastrointestinal tract. Since the introduction of the broadspectrum antibiotics, it has become possible to greatly reduce the bacterial content of the intestine and, as a consequence, to decrease the amount of vitamin K produced, leading to hemorrhagic diathesis. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 129


Question: Familial hypercholesterolemia is

Familial Hypercholesterolemia, or Type IIa hyperlipoproteinemia is defect in LDL-receptors or defect in Apo B100 apoprotein. In this disease, LDL levels & cholesterol is raised in blood. It is Autosomal dominant (AD). ADDITIONAL INFORMATION ON HYPERLIPOPROTEINEMIA: Type Defect Lipoprotein increased TGs Cholesterol Name I Lipoprotein Lipase or Apo C- II Chylomicron || VLDL | || Normal Familial Hyperchylomicronemia (AR) IIa LDL - receptor or Apo B100 LDL|| Normal || Familial Hypercholesterolemia IIb Unknown VLDL| LDL| | | Familial combined Hyperlipoproteinemia (AR) III Apo E Chylomicron Remanant || VLDL remnant | || || Dysbeta - lipoproteinemia or Broad - Beta disease (AR)


Question: Post translational modification of lysine and proline is by


Question: Iron in heme is linked to globin through

Ans. a (Histidine) (Ref. Harper's biochemistry 27th ed., Chapter 6,12; Harrison's 17th/ pg. 635)Heme, an essentially planar, slightly puckered, cyclic tetrapyrrole, has a central Fe2+ linked to all four nitrogen atoms of the heme, to histidine F8, and, in oxyMb and oxyHb, also to O2.The Hemoglobin:# Heme synthesis:- Occurs in the liver and bone marrow.- Committed step is glycine + succinyl CoA -delta aminolevulinate (ALA Synthase required).- Lead inhibits ALA dehydratase and ferrochelatase, preventing incorporation of iron and causing anemia and porphyria.# Glutathione reductase requires NADPH for its action. In G6PD deficiency NADPH cannot be generated at the normal rate and hence oxidants cannot be destroyed, which in turn cause damage, both to hemoglobin and cell membrane cause hemolysis.# Solubility and reversible oxygen binding, both depend most on the hydrophilic surface amino acids, the hydrophobic amino acids lining the heme pocket, a key histidine in the F helix, and the amino acids forming the a1 b1, and a1 b2 contact points.# Hemoglobin is a tetramer composed of 4 globin molecules; 2 alpha globins and 2 beta globins. The alpha globin chain is composed of 141 amino acids and the beta globin chain is composed of 146 amino acids. Both alpha and beta globin proteins share similar secondary and tertiary structures, each with 8 helical segments (labeled helix A-G).# Each globin chain also contains one heme molecule. Heme, an essentially planar, slightly puckered, cyclic tetrapyrrole, has a central Fe2+ linked to all four nitrogen atoms of the heme, to histidine F8, and, in oxyMb and oxyHb, also to O2 The heme molecule is located between helix E and helix F of the globin protein. The alpha and beta subunits of the globin chains exist in two dimers, which are bonded together strongly. The four Pyrole rings are joined by Methylene or Methylidene bridge (-C = bridge).# In Heme synthesis, the two starting materials are succinyl-CoA and glycine. Pyridoxal phosphate is also necessary in this reaction to "activate" glycine.


Question: Specific cell surface proteins, such as alkaline phosphatase, and lipoprotein lipase, are anchored to the cell membrane. This anchoring is accomplished by covalent binding through an oligosaccharide bridge to the component of the cell membrane. This component is

Phosphatidylinositol derivatives play several distinct roles in the cell membrane, one of which is that they anchor several cell surface proteins. Cell surface proteins bound to phosphatidylinositol are also found in several parasitic protozoa. By altering these proteins, these protozoa can change their antigenic propeies and avoid immunosurveillance. Being attached a telatively long chain to the membrane phosphatidylinositol, rather than being a pa of the membrane itself, allows these proteins lateral movement on the cell surface. The proteins can be cleaved from the membrane by the action of phospholipase C. The other compounds listed are also phospholipids, but they do not anchor proteins in the membrane.


Question: Catecholamines are synthesized from

Tyrosine -------------------->DOPA ---------------->dopamine ----------------->norepinephrine ----------------->epinephrine (catecholamines)Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 235


Question: Apoprotein A is found in a) Chylomicronsb) VLDLc) HDLd) LDL

HDL > Chylomicrons

The major apolipoprotein of HDL is apo-A, whereas major apolipoprotein of VLDL, LDL, and chylomicrons is apo-B; apoB-100 in VLDL and LDL, and apoB-48 in chylomicrons.
Apo-A → HDL, chylomicrons
ApoB-100 → LDL, VLDL, EDL
ApoB-48 → Chylomicrons
Apo-C → Chylomicrons, VLDL, HDL
Apo-D → HDL
Apo-E → Chylomicrons, VLDL, HDL


Question: Hemolytic anaemia is seen most commonly due to

Pyruvate kinase deficiency is an inherited disorder that affects red blood cells, which carry oxygen to the body&;s tissues. People with this disorder have a condition known as chronic hemolytic anemia, in which red blood cells are broken down (undergo hemolysis) prematurely, resulting in a shoage of red blood cells (<a href=" Specifically, pyruvate kinase deficiency is a common cause of a type of inherited hemolytic anemia called hereditary nonspherocytic hemolytic anemia. In hereditary nonspherocytic hemolytic anemia, the red blood cells do not assume a spherical shape as they do in some other forms of hemolytic anemia.


Question: Maximum number of unusual base pairs are seen in

The transfer RNA show extensive internal base pairing and acquire clover leaf like structures. They contain a significant propoion of unusual bases. These include dihydrouracil (DHU) pseudouridine (Ps) and hypoxanthine. Moreover, many bases are methylated. REFERENCE : DM.VASUDEVAN.TEXTBOOK SEVENTH EDITION ; PAGE NO : 596.


Question: Electron transpo chain is located in

Localisation: The ETC is localised in the mitochondria. The outer membrane of mitochondria is permeable to most of the small molecules. There is an intermediate space which presents no barrier to passage of intermediates. The inner membrane shows a highly selective permeability. It has transpo systems only for specific substances such as ATP, ADP, pyruvate, succinate, a-ketoglutarate, malate, and citrate etc (Refer Fig. 10.1). The enzymes of the electron transpo chain are embedded in the inner membrane in association with the enzymes of oxidative phosphorylation.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th Edition, Page no: 138


Question: Branching enzyme is found in

Glycogen synthesis:- i. The glycogen synthase can add glucose units only in the alpha-1,4 linkage. A branching enzyme is needed to create the alpha-1,6 linkages. ii. When the chain is lengthened to 11 - 12 glucose residues, the branching enzyme will transfer a block of 6 to 8 glucose residues from this chain to another site on the growing molecule. The enzyme amylo--transglucosidase (branching enzyme) forms this alpha-1,6 linkage (Fig. 9.37). iii. To this newly created branch, fuher glucose units can be added in alpha-1,4 linkage by glycogen synthase.Ref: DM Vasudevan, 7th edition, page no: 125


Question: HMP shunt is of great importance in cellular metabolism because it produces


Question: The amino acid producing ammonia in kidney is

Ans. is 'a' i.e. Glutamine Ammonia ( N 3/4 ) is produced by the hydrolysis of Glutamine by the enzyme glutaminase in renal tubular cells H2OGlutamine - Glutamic acid + NH3 (or Glutamate) GlutaminaseGlutamic acid can be further catalyzed by glutamic dehydrogenase into a-ketoglutarate producing more ammonia.Ammonia being lipid soluble readily diffuses across the cell membranes into the tubular urine. In the urine it reacts with H+ from NH4+ and the NH4+ remains in the urine.Production of ammonia is one of the renal mechanisms of acid-base balanceThe NH3 production is greatly increased in metabolic acidosis and negligible in alkalosis.If the cells require more NH3, it can be formed from glycine by glycine oxidase and other amino acids by L-amino acid oxidase (Production of ammonia from glutamine in the principal mechanism).


Question: Keratan sulphate is found in abundance in

Keratan sulphate:*Seen in: costal cailages, cornea, nucleus pulposus and wall of aoa*Comp: n*No URONIC ACID*Sulphate is in both gal and glucosamine


Question: Interaction involved in primary structure of protein

Primary Structure: Primary structure is the linear sequence of amino acids held together by peptide bonds in its peptide chain. The peptide bonds form the backbone and side chains of amino acid residues project outside the peptide backbone. The free -NH2 group of the terminal amino acid is called as N-terminal end and the free -COOH end is called as C-terminal end. It is a tradition to number the amino acids from N-terminal end as No. 1 towards the C-terminal end. Presence of specific amino acids at a specific number is very significant for a paicular function of a protein. Any change in the sequence is abnormal and may affect the function and propeies of protein.Ref: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 89


Question: A dideoxynucleotide does not contain

Dideoxy nucleotide Lacks 3' OH group also. Stop the chain elongation when they are incorporated. DNA polymerase requires 3' OH group to begin polymerisation. Use: Sanger chain termination method of DNA sequencing. Didanosine is a dideoxynucleotide used in the therapy of HIV.


Question: Active form of vitamin Li is

1,25(011) 2 vit-D (Ref: Harper 26/e, p 484-485; Harrison 16/e, p 2246: Chatterjee Shinde Biochemistry 6/e, p 151] Synthesis and metabolism of Vitamin D Calcidiol may undergo 24-hydroxylation to yield an inactive metabolite, 24, 25-dihydroxy vit. D mediated by vit. D 24 - hydroxylase. 1, 25 (01-1)2D is the major inducer of vit-D-24 hydroxylase, thus promotes its own inactivation, thereby limiting its biologic effects.


Question: Histone acetylation causes

Histone acetylation and deacetylation are the processes by which the lysine residues within the N-terminal tail protruding from the histone core of the nucleosome are acetylated and deacetylated as pa of gene regulation. Histone acetylation and deacetylation are essential pas of gene regulation. These reactions are typically catalysed by enzymes with "histone acetyltransferase" (HAT) or "histone deacetylase" (HDAC) activity. Acetylation is the process where an acetyl functional group is transferred from one molecule (in this case, Acetyl-Coenzyme A) to another. Deacetylation is simply the reverse reaction where an acetyl group is removed from a molecule. Acetylated histones, octameric proteins that organize chromatin into nucleosomes and ultimately higher order structures, represent a type of epigenetic marker within chromatin. Acetylation removes the positive charge on the histones, thereby decreasing the interaction of the N termini of histones with the negatively charged phosphate groups of DNA. As a consequence, the condensed chromatin is transformed into a more relaxed structure that is associated with greater levels of gene transcription. This relaxation can be reversed by HDAC activity. Relaxed, transcriptionally active DNA is referred to as euchromatin. More condensed (tightly packed) DNA is referred to as heterochromatin. Condensation can be brought about by processes including deacetylation and methylation; the action of methylation is indirect and has no effect upon charge.


Question: Codon consist of

DNA is a reference for proteins, which are the functional molecules in cells. These are comprised of 20 unique amino acids, and each is coded for by a stretch of DNA known as a codon. Codons are always 3 base-pairs (nucleotides) in length.Ref: Harper&;s Biochemistry; 30th edition


Question: Phenylbutyrate is used in the treatment of urea cycle disorders, because

Phenylbutyrate and sodium benzoate act as ammonia(nitrogen) scavengers.


Question: Deficiency of purine nucleoside phosphorylase causes

A combined T cell and B cell immunodeficiency that is a rare autosomal recessive metabolic disorder that has material basis in mutation in the PNP gene and characterized mainly by decreased T-cell function. Ref-Sathyanarayana 4/e


Question: Iron overload

Normal plasma contains very little ferritin. Ferritin in plasma is elevated in iron overload. Thus ferritin level in blood is an index of body iron stores. iv. Ferritin is an acute phase reactant protein that is elevated in inflammatory diseases. Estimation of ferritin is also indicated in chronic kidney disease to assess the extent of anemia. v. Synthesis of TfR and ferritin and that of ferritin are reciprocally controlled. Both are controlled by the iron content. When iron levels are high, ferritin is synthesized to store the iron; but the TfR synthesis is blocked. When iron levels are high, iron binds to iron-response-element- binding-protein (IREBP), preventing it from binding to IRE. This will result in synthesis of new ferritin, and suppression of synthesis of TfR. Transferrin receptors (TfR) are present on most of the body cells, especially on cells which synthesize heme. The iron-transferrin complex is taken up by the body cells by the receptor mechanism. The transferrin receptor has a molecular weight of 200 kD. It binds two molecules of transferrin. The iron-transferrin- receptor is internalized. Iron is taken in by the cells, and receptor molecules are externalized. vii. Transferrin is a glycoprotein. Abnormal glycosylation is seen in congenital disorders and in chronic alcohol abuse.Ref: DM Vasudevan, page no: 425

Cannot occur because very efficient excretory mechanism are available

Would be accompanied by an increase in total serum transferrin

Might be caused by an ingestion of large amounts of iron along with alcohol


Question: Folding of protein chain is due to

In the concept of orders of protein structure: primary structure--the sequence of amino acids in a polypeptide chainsecondary structure--the folding of sho, contiguous segments of the polypeptide into geometrically ordered units teiary structure--the assembly of secondary structural units into larger functional units such as the mature polypeptide and its component domainsquaternary structure--the number and types of polypeptide units of oligomeric proteins and their spatial arrangement.Two most common types of secondary structure, the a helix, and the b sheet.The stability of an a helix arises primarily from hydrogen bonds formed between the oxygen of the peptide bond carbonyl and the hydrogen atom of the peptide bond nitrogen of the fouh residue down the polypeptide chainLike the a helix, b sheets derive much of their stability from hydrogen bonds between the carbonyl oxygens and amide hydrogens of peptide bonds. However, in contrast to the a helix, these bonds are formed with adjacent segments of the b sheetRef: Harper&;s Biochemistry; 30th edition; Pg: 38


Question: Hormone necessary for water and sodium balance

Ans: d (Aldosterone)Ref: Vasudevan & Sreekumari, 6th edi., Pg. 357Aldosterone is secreted by zona glomerulosa of the adrenal cortex. It regulates sodium-potasium exchange and sodium-hydrogen exchange at the renal tubules.The net effect is the sodium retention


Question: Carbamoyl phosphate synthase I is used in

Carbamoyl phosphate synthase 1 conve CO2 + NH4 to Carvomyl phosphate Ref-Harpers illustrated biochemistry 30/e p680


Question: Amino acid produced by adding hydroxyl group to phenyl side chain of phenylalanine

Ans: c. (tyrosine) Ref: Vasudevan Sreekumari, 6th edi., pg. 203Amino acids having phenyl side chain are called aromatic amino acid.Aromatic amino acids are - phenylalanine, tyrosine Phenylalanine is converted to tyrosine. The reaction involves addition of a hydroxyl group to the aromatic (phenyl) ring, by phenylalanine hydroxylase. It needs NADPH, NADH and tetrahydrobiopterin as co enzymes.As this reaction is irreversible reaction, tyrosine cannot replenish phenylalanine. Hence phenylalanine is an essential amino acid.Serine, threonine are aliphatic hydroxy aminoacidsTryptophan, histidine are heterocyclic amino acids having indole and imidazole group respectively. Proline is animino acid because it has a secondary amino group, pyrrolidine group.


Question: Poly (A) tail translates into

A poly (A) tail is added to the 3&; end of the pre-mRNA once elongation is complete. The poly (A) tail protects the mRNA from degradation, aids in the expo of the mature mRNA to the cytoplasm, and is involved in binding <a href=" involved in initiating translation.


Question: Enzyme defect in Classic Phenylketonuria

Hyperphenylalaninemias arise from defects in phenylalanine hydroxylase (type I, classic phenylketonuria (PKU), frequency 1 in 10,000 bihs), in dihydrobiopterin reductase (types II and III), or in dihydrobiopterin biosynthesis (types IV and V).Ref: Harper&;s Biochemistry; 30th edition; Chapter 29 Catabolism of the Carbon Skeletons of Amino Acids


Question: Imidazole ring is present in

Ans. is 'c' i.e.,Histidine Some amino acids contain a special functional group in their side chain which provide some specific functions to that amino acids. These are : Hydroxyl group in serine and threonine - Indole ring in tryptophanAmide group in aspargine and glutamine - (3-Carboxyl in glutamic acidThioether in methionine - Imidazole in histidineSulphydryl in cysteine - Phenol in tyrosiney-carboxyl in glutamic acid - Pyrrolidine in prolineGuanidinium in arginine - c-amino in lysine


Question: Enzyme deficiency seen in genetic diseases like

Tay-Sachs disease is a genetic disorder due to the deficiency of enzyme Hexosaminidase A. The disease occurs when harmful quantities of cell membrane components known as gangliosides accumulate in the brain&;s nerve cells, eventually leading to the premature death of the cells. symptoms: mental retardation, blindness, muscular weakness.Sickle cell anemia is an autosomal genetic disorder. Mutations in the globin genes that alter the protein composition, mutations leading to qualitative alterations in hemoglobin, the missense mutation in the b-globin gene that causes sickle cell anemia.T he mutation causing sickle cell anemia is a single nucleotide substitution (A to T) in the codon for amino acid 6. The change conves a glutamic acid codon (GAG) to a valine codon (GTG). The form of hemoglobin in persons with sickle cell anemia is referred to as HbS.Cystic fibrosis (CF) is an inherited disease that affects the secretory glands, including the mucus and sweat glands. Cystic fibrosis mostly affects the lungs, pancreas, liver, intestines, sinuses, and sex organs. CF is due to a mutation in the CF gene on chromosome 7. The CF gene encodes a protein known as the cystic fibrosis transmembrane regulator (CFTR). The abnormal CFTR protein in patients with CF leads to disruption of chloride channels on the cells.Wilson&;s disease is a genetic disorder in which copper builds up in the body. Wilson&;s disease is an autosomal recessive condition due to a mutation in the Wilson disease protein (ATP7B) gene. For a person to be affected they must inherit an affected copy of the gene from each parent.Ref: Harper&;s biochemistry, 30th edition, page: 251


Question: C terminal end of androgen receptor is concerned with

Activation function 2 (AF-2), responsible for agonist-induced activity (activity in the presence of bound agonist)Ref: DM Vasudevan, 7th edition, page no: 669

Increasing the affinity of receptor to DNA


Question: Synthetic Orygen carrier is made up of_

Ans. is 'd' i.e., FlurineBlood doping is a form of fraudulent increase in the oxygen carrying capacity of a person, widely used to improve the aerobic capacity of athletes.


Question: Consumption of raw egg may lead to deficiency of

Biotin (formerly known as anti-egg white injury factor Boas (1927) observed that rats fed huge quantity of raw egg white developed dermatitis and nervous manifestations & retardation in growth found that feeding cooked egg did not produce any of these symptoms It was shown that the egg white injury in rats and chicks (Boas experiment) was due to the presence of an anti-vitamin in egg white The egg-white injury factor was identified as a glycoprotein- avidin and biotin was called as anti-egg white injury factor. ref Satyanarayana 4th ed page 146


Question: Tetrahydrobiopterin is required for the metabolism of

THB is a cofactor for Aromatic amino acid (Tryptophan, Phenylalanine & Tyrosine) hydroxylases (See Fig)* Nitric acid synthase Serotonin synthesis Non-classical phenylketonuria types are due to defect in the synthesis or recycling of THB. Tetrahydrobiopterin (THB) is a nucleotide cofactor derived from Guanosine triphosphate.


Question: Xanthurenic acid is the metabolite in the metabolism of

3-Hydroxy Kynurenine is one of the intermediate in tryptophan catabolism, which gets conveed to next intermediate and this conversion requires vitamin B6/ PLP. So, in B6 deficiency, this reaction does not occur and 3-Hydroxy Kynurenine is diveed to form alternate metabolite, Xanthurenic acid (See fig), which is excreted in urine

Classification and metabolism of amino acids


Question: DNA fingerprinting is based on possessing in DNA of

These are tandem repeatsThese are sho sequence of DNA located at scattered sites The no. Of these repeat units varies from person to person but is it unique for paicular personProbability of similarity between two people is only 1 in 3*10^10 personsRef: DM Vasudevan, 7th edition, page no: 637


Question: Carboxylases require

Biotin, vitamin B7, or vitamin H, is a water-soluble vitamin. The vitamin plays a role in the transferring of carbon dioxide in the metabolism of fat, carbohydrate and protein by functioning as an enzyme cofactor. It is involved in multiple biochemical reactions including niacin metabolism, amino acid degradation, and the formation of purine, which is an integral pa of nucleic acids. It interacts with histone by the action of biotinyl-transferase. Sometimes the vitamin is used in weight reduction programs. It may be prescribed as a supplement for diabetic patients due to its role in carbohydrate metabolism. Biotin is commonly found in vitamin B complex and many food sources, such as milk, yeast, egg yolk, cereal, and mushrooms. The reference daily intake for vitamin B7 is 300 micrograms. Deficiency in the vitamin may result in seborrheic dermatitis, alopecia, myalgia, hyperesthesia, and conjunctivitis. Disorders of biotin metabolism can be acquired or congenital. Biotinidase and holocarboxylase synthetase deficiency are the two better-known forms of disorders. The lack of biotin-dependent pyruvate carboxylase, propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, and acetyl-CoA carboxylase can lead to the life-threatening disorder of multiple carboxylase deficiency. Treatment involves a daily dose of approximately 10 mg biotin/day. Irreversible mental or neurological abnormalities may result from delayed clinical intervention.


Question: OTC deficiency causes

Ans. is 'd' i.e., Hyperammonemia type-2Orinithine transcarbomylase (OTC) deficiency causes hyperammonemia type-2.


Question: An enzyme that makes a double stranded DNA copy from a single stranded RNA template molecule is known as

Reverse transcriptase is an RNA dependent DNA polymerase that produces ds DNA from RNA template. It moves along the template in 3' → 5' direction, synthesizing DNA is 5' → 3' direction.
It is seen in retro viruses (e.g. HIV).


Question: The formation of glycine takes place by transamination of


Question: Nicotinamide is derived from

The enzyme QP Is the rate limiting step in the formation of nicotinamide from Tryptophan.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 240


Question: Bromodeoxyuridine in DNA is related to

Bromodeoxy uridine is thymidine analogue.


Question: Exogenous adrenaline is metabolished by

Exogenous adrenaline is metabolised by Catechol-O-methyltransferase (COMT) in liver and other tissues. Metabolism does not play an impoant role in terminating the action of endogenous catecholamines. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 441


Question: RFLP is used for

Reastiction fragment length polymophism (RFLP) : A polymorphic gene is one ,in which the variant alleles are commonin more than 1% of the total population. The existence of two or more types of restriction fragment patterns is called restiction fragment length polymorphism (RFLP). This can be used as a genetic marker. DNA is treated with restriction enzymes, which cleave DNA into fragments of lengths. The electrophoresis is done in agarose gels, when the fragments are seperated. Finally, the DNA from the agarose gel is transferred on to nitrocellulose paper (southern blotting)and hybridized with labeled probe sequences. Genotypic changescan be recognized by the altered restriction fragments. REF : DM VASUDEVAN TEXTBOOK ,7th EDITION , Page no no :637.


Question: DNA labelling is done by using

Ans. is 'b' i.e., P-32 The simplest form of labelling DNA is by 5'- or 3'- end labelling.5`-end - labelling involves a phophate transfer or exchange reaction where the 5' - phosphate of the DNA to be used as the probe is removed and in its place a labelled phasphate, usually P32 is added.In 3'-end-labelling, labelled dNTP (ATP or biotin-labelled dNTP) is added to 3' end of DNA by enzyme terminal transferase.


Question: Inve sugar is

Sucrose on hydrolysis yields D glucose and D-fructose. But the optical rotation changes from dextrorotatory to leavorotatory. Hence the hydrolytic products of sucrose are called as inve sugar.


Question: Protein is purified using ammonium sulfate by

The process of protein precipitation by the addition of neutral salts such as Ammonium sulfate or Sodium sulfate is called salting out. This phenomenon is explained on the basis of dehydration of protein molecules by salts. This increased protein_protein interaction,resulting in molecular aggregation and precipitation.TSalting out procedure is conveniently used for separating serum albumins from globulins


Question: The general test for detection of carbohydrates is

Molisch test: It is a general test for the detection of carbohydrates. The strong H2SO4 hydrolyzes carbohydrates (poly and disaccharides) to liberate monosaccharides. The monosaccharides get dehydrated to form furfural (from pentoses) or hydroxymethyl furfural (from hexoses) which condense with a-naphthol to form a violet colored complex. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 17


Question: Endogenous production of Niacin is from

Ans. c (Tryptophan) (Ref. Harper's Biochemistry 27th ed. 498)# Niacin is synthesized from Tryptophan.# 60 mg of Tryptophan gives 1 mg equivalent of niacin.# Active forms of Niacin, are NAD* and NADP+.Educational points:AMINO ACID DERIVATIVES# Ornithine -Putrescine - Spermidine ->>Spermine (Polyamine biosynthesis - One of the earliest signals that cells have entered their replication cycle is the appearance of elevated levels of mRNA for ornithine decarboxylase (ODC), and then increased levels of the enzyme, which is the first enzyme in the pathway to synthesis of the polyamines.)# Arginine -^Citrulline + NO


Question: Phosphorylase b is maintained in an inactivated state by


Question: An L isomer of monosaccharide formed in the human body is

Monosaccharides are those sugars that cannot be hydrolyzed into simpler carbohydrates. They may be classified as trioses, tetroses, pentoses, hexoses, or heptoses, depending upon the number of carbon atoms (3-7), and as aldoses or ketoses, depending on whether they have an aldehyde or ketone group. d and l isomerism: The designation of a sugar isomer as the d form or its mirror image as the l form is determined by its spatial relationship to the parent compound of the carbohydrates, the three-carbon sugar glycerose (glyceraldehyde).Pentoses of Physiological ImpoanceSugarBiochemical and ClinicalImpoanced-RiboseStructural component ofnucleic acids andcoenzymes, includingATP, NAD(P), and flavincoenzymesd-RibuloseIntermediate in the pentosephosphate pathwayd-ArabinoseConstituent of glycoproteinsd-XyloseConstituent ofglycoproteinsl-XyluloseExcreted in the urine inessential pentosuriaRef: Harper&;s Biochemistry; 30th edition; Chapter 15; Carbohydrates of Physiological Significance


Question: First substrate of Kreb&;s cycle is

Acetyl CoA enters the cycle and is completely oxidized. During this process, energy is trapped. The sources of acetyl CoA are shown in Figure 18.1. Pyruvate derived from glycolysis is oxidatively decarboxylated to acetyl CoA by pyruvate dehydrogenase (Fig. 9.22). This is the link between the TCA cycle and glycolysis. The pyruvate dehydrogenase reaction occurs in the mitochondria. Pyruvate with the help of a carrier can enter the mitochondria from the cytoplasm. The acetyl CoA derived from beta-oxidation is formed in the mitochondria itself. All the enzymes of citric acid cycle are located inside the mitochondria.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 216


Question: Anticholinesterase that binds only with the anionic site is


Question: Menkes Kinky hair syndrome is characterized by a congenital deficiency of

Menkes disease ("Kinky" or "steely" hair disease) is a disorder of copper metabolism due to mutations in the gene for a copper-binding P-type ATPase, i.e. ATP7A gene.


Question: In urea cycle, hydrolysis of arginine forms

Hydrolysis of arginine by enzyme arginase produce ornithine and urea Ref-Sathyanarayana 4/e p393


Question: Galactosemia commonly is due to deficiency of

Galactose-1 phosphate uridyl transferase
Galactosemia is due to deficiency of :

Galactose-1-phosphate uridyl transferase (most common and best known),
Galactokinase, and
UDP-Galactose-4-epimerase.


Question: The enzyme diagnostic of MI in a case of hypothyroidism is

Commonly used biomarkers for early detection of acute myocardial infarction are 1. Cardiac troponins, TnI and TnT 2. Creatine kinase, CK-MB 3. Myoglobin. Of these, troponins and CK-MB are the sensitive and specific markers, whereas myoglobin though sensitive, is non-specific Predictors of risk in cardiac disease are of two types: a. for predicting the onset of ischemia b. those which quantify the ventricular damage The risk predictors mainly include the atherogenic lipoproteins in plasma along with the inflammatory marker like hsCRP (high sensitive C reactive protein).Ref: DM Vasudevan


Question: House keeping genes are


Question: G6PD stands for

G6PD-glucose 6 phosphate dehydrogenaseRef: DM Vasudevan, 7th edition, page no: 67


Question: A deficiency of substance iron can result in an anemia. Choose the type of anemia that would occur if the substance were deficient.

Cytochromes in complex III receive electrons from the reduced form of CoQ.a. Each cytochrome consists of a heme group (see Figure below) associated with a protein.b. The iron of the heme group is reduced when the cytochrome accepts an electron.Fe3+=Fe2+An iron-deficiency anemia is characterized by small, pale RBCs. The lack of iron reduces the synthesis of heme, so the red cells cannot carry as much oxygen (which gives them the pale color). The cells are small in order to maximize the concentration of hemoglobin present in the cells. A megaloblastic anemia is caused by deficiencies in either vitamin B12 or folic acid (a lack of intrinsic factor will lead to a B12 deficiency named pernicious anemia). These cells are large because the vitamin deficiency interferes with DNA synthesis, and the cells double in size without being able to replicate their DNA. Once the anemia begins, the large blast cells are released by the marrow in an attempt to control the anemia. Hemolytic anemia occurs when the red cell membrane fragments, which can occur with pyruvate kinase deficiencies or a lack of glucose-6-phosphate dehydrogenase activity (which results in reduced NADPH levels). Sickle cell anemia is caused by a point mutation in the b-globin gene, substituting a valine for a glutamic acid.The general structure of the heme group, which is present in hemoglobin, myoglobin, and the cytochromes b, c, and c1. Each cytochrome has a heme with a different modification of the side chains (indicated with the dashed lines), resulting in a slightly different reduction potential and, consequently, a different position in the sequence of electron transfer.


Question: Not product of transcriptiona) tRNAb) mRNAc) rRNAd) cDNAe) New strand of DNA

In transcription RNA is formed from DNA.


Question: Restriction endonucleases are the enzymes

Ans. b (They cleave the DNA at specific sequence) (Ref. Harper's Illustrated Biochemistry, 26lh/57, 397; Table 40-2)RESTRICTION ENDONUCLEASES# Restriction enzyme: An endodeoxynuclease that causes cleavage of both strands of DNA at highly specific sites dictated by the base sequence.# The detection of restriction fragment length polymorphisms (RFLPs) facilitates prenatal detection of hereditary disorders such as:- Sickle cell trait,- Beta thalassemia,- phenylketonuria, and- Huntington's disease.# Detection of RFLPs involves cleavage of double-stranded DNA by restriction endonucleases, which can detect subtle alterations in DNA that affect their recognized sites.Enzymes capable of degrading nucleic acids (nucleases) can be classified in several ways:# Those which exhibit specificity for deoxyribonucleic acid are referred to as deoxyribonucleases.# Those which specifically hydrolyze ribonucleic acids are ribonucleases.# Within both of these classes are enzymes capable of cleaving internal phosphodiester bonds to produce either 3'- hydroxyl and 5'-phosphoryl terminals or 5'-hydroxyl and 3'-phosphoryl terminals. These are referred to as endonucleases.# There exist classes of endonucleases that recognize specific sequences in DNA; the majority of these are the restriction endonucleases, which have in recent years become important tools in molecular genetics and medical sciences.# Some nucleases are capable of hydrolyzing a nucleotide only when it is present at a terminal of a molecule; these are referred to as exonucleases.- Exonucleases act in one direction (3-5 or 5-3) only. In bacteria, a 3-5 exonuclease is an integral part of the DNA replication machinery and there serves to edit--or proofread--the most recently added deoxynucleotide for base- pairing errors.Educational points:# Restriction enzymes cut DNA of any source into short pieces in a sequence-specific manner--in contrast to most other enzymatic, chemical, or physical methods, which break DNA randomly.# Restriction enzymes & DNA ligase are also used to prepare chimeric DNA molecules.


Question: The vitamin present in the fatty acid synthase complex is

Fatty acid synthase: In yeast, mammals, and birds, the synthetase enzyme system is called the fatty acid synthase complex--it is a multienzyme complex. It is made up of an ellipsoid dimer of two identical polypeptide monomeric units (monomer I and II), arranged in a "head to tail" fashion. Each monomeric unit contains six enzymes and an ACP molecule (Acyl carrier protein). Active Site * The ACP has an -SH group in the 4-phosphopantetheine moiety, referred as Pantothenic-SH (Pan-SH) * Another active -SH group present in the cysteine moiety of the enzyme ketoacyl synthase (condensing enzyme), referred as cysteinyl-SH (Cys-SH). The "Pan-SH" of one monomeric unit is in close proximity to the "Cys-SH" group of other monomeric unit and vice-versa.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 414


Question: The important intermediate product of biosynthesis of fatty acid is

Malonyl CoA

Acetyl-CoA is the immediate substrate for fatty acid synthesis.
However, acetyl-CoA needs to be converted to the activated form, which will serve as the donor of carbon units to the growing fatty acid chain.
Malonyl-CoA is such activated form; acetyl-CoA is converted to malonyl-CoA by acetyl-CoA carboxylase.


Question: Not a component of PCR

POLYMERASE CHAIN REACTION (PCR) : PCR is an in vitro DNA amplication procedure in which milions of copies of a paicular sequence of DNA can be produced within a few hours. The flanking sequences of the gene of interset should be known. Two DNA primersof about 20 -30 nucleotides with complementary sequence of the flanking region can be synthesized. STEP 1 :Seperation (Denaturation) : DNA strands are seperated ( melted ) by heating at 95 Degree Celsius for 15 sec to 2 mins. STEP 2 :Priming ( Anneling ) : The primers are annealed by cooling to 50 degree celsius fo 0.5 to 2min. STEP 3 :Polymerization : Nw DNA strands are symnthesized by Taq polymerase.These enzyme is derived from bactris Thermus acquaticus that are found in hot springs.Therefore the enzyme is not denatured at high temperature. The polymerase reaction is allowed to take place 72 degree celscius for 30 sec in presence of dNTPs.Both DNA strands are duplicated in this step. STEP 4 :The steps of 1, 2 and 3 are repeated .In each cycle, the DNA strands are doubled.Thus 20 cycles provide for 1 million times amplificatins. These cycles are generally repeated by automated instument, called Thermal cycler. STEP 5 : After the amplification procedure, DNA hybridization technique or southern blot analysis with a suitable probe, shows the presence of the DNA in the sample tissue. REF :DM VASUDEVAN TEXTBOOK :7th EDITION ; Page no :638


Question: Induced fit hypothesis was proposed by


Question: Covalent bond is seen in

Disulphide bonds: These are formed between two cysteine residues. They are strong, high energy covalent bonds.Ref: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 89


Question: Basophilic stippling is due to

(C) (5'- nucleotides deficiency) (880-H 18(tm))Lead intoxication is accompanied by an acquired deficiency of erythrocyte pryimidine-specific, 5'-nucleotidase.Genetically determined deficiency of this enzyme is associated with chronic hemolysis, marked basophilic stippling of erythrocytes on stained blood films, and unique intraerythrocytic accumulations of pyrimidine-containing nucleotides.Basophilic stippling aka Punctatebasophilia refers to an observation found when observing a blood smear in which erythrocytes display small dots at the periphery. These dots are the visualization of ribosomes and can often be found in the peripheral blood smear, even in some normal individuals.Pyrimidine 5'- nucleotides (P 5 N) deficiency- P5N is a key enzyme in the catabolism of nucleotides arising from the degradation of nucleic acids that takes place in the final stages of erythroid cell maturation. How exactly its deficiency causes Hemolytic anemia is not well understood; but a highly distinctive features of this condition is a morphologicabnormality of the red cells known as basophilic stipplingHemolytic anemia caused by lead poisoning is characterized by basophilic stippling. It is infact a phenocopy of that seen in P5N deficiency, suggesting it is mediated at least in part by lead inhibiting then enzymeCauses of Basophilic Stippling in blood smear1. Thalassemias2. Hemoglobin s S - disease3. Hemoglobin s C disease4. Hemoglobin s E disease5. Iron deficiency6. Unstable hemoglobin s / Myelodysplasia7. Lead poisoning* Basophilic leucocytoses is seen in CML *


Question: In well fed state gluconeogenesis in liver is inhibited by


Question: Enzymatic activity is measured in

Enzyme activity is expressed as micromoles of substrate conveed to product per minute under specified assay conditions. One standard unit (or International Unit) of enzyme activity (U) is the amount of enzyme that will conve one micromole of substrate per minute per litre of sample and is abbreted as U/L.Ref: DM Vasudevan, Page no: 58


Question: Stimulates the production of IGF.

GH stimulates the release of IGF by the liver and other tissues. The other hormones listed do not stimulate IGF release from any tissue.


Question: Serine proteases

It is otherwise called alpha-anti-proteinase or protease inhibitor. It inhibits all serine proteases (proteolytic enzymes having a serine at their active center), such as plasmin, thrombin, trypsin, chymotrypsin, elastase, and cathepsin. Serine protease inhibitors are abbreted as Serpins. They are enzymes with a serine residue at the active site and most of the proteolytic enzymes belong to this group, e.g. trypsin, chymotrypsin, clotting factors Serine proteases examples-Trypsin, Chymotrypsin,Clotting factorsRef: DM Vasudevan, Page no: 44

Hydrolyze peptide bonds involving carboxyl groups of serine residues

Are characterized by having several active sites per molecule, each containing a serine residue

Are inactivated by reaching with one molecule of di-isopropyl-fluorophosphate per molecule of protein


Question: Michaelis Menten Hypothesis states that

Michaelis-Menten Theory (Enzyme-Substrate Complex Theory)
Enzyme combines with a substrate to form a transient Enzyme-Substrate Complex which immediately break into Enzyme and products.

Rate of enzymatic reaction is independent of substrate concentration

Rate of non enzymatic reaction is proportional to substrate concentration

Km is the enzyme substrate complex association constant

Enzyme substrate complex formation is essential in enzymatic reaction.


Question: Pseudouridine is seen in

Pseudouridine Is Excreted Unchanged No human enzyme catalyzes hydrolysis or phosphorolysis of the pseudouridine (ps) derived from the degradation of tRNA molecules. This unusual nucleotide, therefore, is excreted unchanged in the urine of normal subjects. Pseudouridine was indeed first isolated from human urineRef: Harpers Illustrated Biochemistry, 30th edition, page no: 356


Question: Total number of dehydrogenases Krebs cycle

Isocitrate dehydrogenase (ICD) enzyme succinate dehydrogenase Malate dehydrogenase a-ketoglutarate dehydrogenaseRef: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 339


Question: The protein synthesis is soed out at/by

Main function of Golgi apparatus is protein soing, packaging, and secretion. Mitochondria are the powerhouse of cell. Detoxification of various drugs is an impoant function of ER. Ribosomes are involved in protein synthesis.Ref: DM Vasudevan - Textbook of Biochemistry for Medical Students, 7th edition, page no: 12


Question: The sequence in a long chain of protein is identified by

"A major use of RFLPs is in the definition of inherited diseases in which the functional deficit is unknown. RFLPs / SNPs can be used to establish linkage groups, which in turn, by the process of chromosome walking, will eventually define the disease locus. In chromosome walking, a fragment representing one end of a long piece of DNA is used to isolate another that overlaps but extends the first. The direction of the extension is determined by restriction mapping and the procedure is repeated sequentially until the desired sequence is obtained."

Restriction fragment length polymorphism (RFLP)