vania-janet/multiturn-rag-retrieval-data huggingface dataset:
T cell
Gamma delta T cells ( γδ T cells ) represent a small subset of T cells that possess a distinct T cell receptor ( TCR ) on their surfaces . A majority of T cells have a TCR composed of two glycoprotein chains called α - and β - TCR chains . However , in γδ T cells , the TCR is made up of one γ - chain and one δ - chain . This group of T cells is much less common in humans and mice ( about 2 % of total T cells ) ; and are found mostly in the gut mucosa , within a population of lymphocytes known as intraepithelial lymphocytes . In rabbits , sheep , and chickens , the number of γδ T cells can be as high as 60 % of total T cells . The antigenic molecules that activate γδ T cells are still widely unknown . However , γδ T cells are not MHC - restricted and seem to be able to recognize whole proteins rather than requiring peptides to be presented by MHC molecules on APCs . Some murine γδ T cells recognize MHC class IB molecules , though . Human Vγ9 / Vδ2 T cells , which constitute the major γδ T cell population in peripheral blood , are unique in that they specifically and rapidly respond to a set of nonpeptidic phosphorylated isoprenoid precursors , collectively named phosphoantigens , which are produced by virtually all living cells . The most common phosphoantigens from animal and human cells ( including cancer cells ) are isopentenyl pyrophosphate ( IPP ) and its isomer dimethylallyl pyrophosphate ( DMPP ) . Many microbes produce the highly active compound hydroxy - DMAPP ( HMB - PP ) and corresponding mononucleotide conjugates , in addition to IPP and DMAPP . Plant cells produce both types of phosphoantigens . Drugs activating human Vγ9 / Vδ2 T cells comprise synthetic phosphoantigens and aminobisphosphonates , which upregulate endogenous IPP / DMAPP .
Ribosome
A ribosome is made from complexes of RNAs and proteins and is therefore a ribonucleoprotein . Each ribosome is divided into two subunits :
Vector (molecular biology)
Viral promoters are often used for constitutive expression in plasmids and in viral vectors because they normally force constant transcription in many cell lines and types reliably . Inducible expression depends on promoters that respond to the induction conditions : for example , the murine mammary tumor virus promoter only initiates transcription after dexamethasone application and the Drosophilia heat shock promoter only initiates after high temperatures .
Cell wall
The group of algae known as the diatoms synthesize their cell walls ( also known as frustules or valves ) from silicic acid ( specifically orthosilicic acid , H SiO ) . The acid is polymerised intra-cellularly , then the wall is extruded to protect the cell . Significantly , relative to the organic cell walls produced by other groups , silica frustules require less energy to synthesize ( approximately 8 % ) , potentially a major saving on the overall cell energy budget and possibly an explanation for higher growth rates in diatoms .
Substrate (chemistry)
For example , curd formation ( rennet coagulation ) is a reaction that occurs upon adding the enzyme rennin to milk . In this reaction , the substrate is a milk protein ( e.g. , casein ) and the enzyme is rennin . The products are two polypeptides that have been formed by the cleavage of the larger peptide substrate . Another example is the chemical decomposition of hydrogen peroxide carried out by the enzyme catalase . As enzymes are catalysts , they are not changed by the reactions they carry out . The substrate ( s ) , however , is / are converted to product ( s ) . Here , hydrogen peroxide is converted to water and oxygen gas .
Glock
The Glock 's frame , magazine body , and several other components are made from a high - strength nylon - based polymer invented by Gaston Glock , called Polymer 2 . This plastic was specially formulated to provide increased durability and is more resilient than carbon steel and most steel alloys . Polymer 2 is resistant to shock , caustic liquids , and temperature extremes where traditional steel / alloy frames would warp and become brittle . The injection - molded frame contains four hardened steel guide rails for the slide : two at the rear of the frame , and the remaining pair above and in front of the trigger guard . The trigger guard itself is squared off at the front and checkered . The grip has an angle of 109 ° and a nonslip , stippled surface on the sides and both the front and rear straps . The frame houses the locking block , which is an investment casting that engages a 45 ° camming surface on the barrel 's lower camming lug . It is retained in the frame by a steel axis pin that holds the trigger and slide catch . The trigger housing is held to the frame by means of a polymer pin . A spring - loaded sheet - metal pressing serves as the slide catch , which is secured from unintentional manipulation by a raised guard molded into the frame .
Glow stick
Glow sticks emit light when two chemicals are mixed . The sticks consist of a tiny , brittle container within a flexible outside container . Each container holds a different solution . When the outer container is flexed , the inner container breaks , allowing the solutions to combine , causing the necessary chemical reaction . After breaking , the tube is shaken to thoroughly mix the two components .
Collagen
Many bacteria and viruses secrete virulence factors , such as the enzyme collagenase , which destroys collagen or interferes with its production .
Shotgun
The wide range of forms the shotgun can take leads to some significant differences between what is technically a shotgun and what is legally considered a shotgun . A fairly broad attempt to define a shotgun is made in the United States Code ( 18 USC 921 ) , which defines the shotgun as `` a weapon designed or redesigned , made or remade , and intended to be fired from the shoulder , and designed or redesigned and made or remade to use the energy of the explosive in a fixed shotgun shell to fire through a smooth bore either a number of ball shot or a single projectile for each single pull of the trigger . '' It is even more broadly defined in English law : `` a smooth bore gun not being an air gun '' ( s. 1 ( 3 ) ( a ) Firearms Act 1968 ) .
Pottery of ancient Greece
The pots were usually made in sections such as the body and feet and spout . Even the body , if it were larger than 20 centimeters , might be made in separate sections and glued together later with a thin watery clay called slip . After the pot is made then the potter paints it with a very pure black slip made from a specially prepared clay using brushes made from a single hair . It was thus slipped and then incised ready for the kiln .
Water fluoridation
Fluoride exerts its major effect by interfering with the demineralization mechanism of tooth decay . Tooth decay is an infectious disease , the key feature of which is an increase within dental plaque of bacteria such as Streptococcus mutans and Lactobacillus . These produce organic acids when carbohydrates , especially sugar , are eaten . When enough acid is produced to lower the pH below 5.5 , the acid dissolves carbonated hydroxyapatite , the main component of tooth enamel , in a process known as demineralization . After the sugar is gone , some of the mineral loss can be recovered -- or remineralized -- from ions dissolved in the saliva . Cavities result when the rate of demineralization exceeds the rate of remineralization , typically in a process that requires many months or years . Demineralization
Protein folding
The diffusion collision model , in which first a nucleus forms , then the secondary structure , and finally these secondary structures collide and pack tightly together . The nucleation - condensation model , in which the secondary and tertiary structures of the protein are made at the same time .
Diphtheria
In 1897 , Paul Ehrlich developed a standardized unit of measure for diphtheria antitoxin . This was the first ever standardization of a biological product , and played an important role in future developmental work on sera and vaccines .
Cigarette
Modern commercially manufactured cigarettes are seemingly simple objects consisting mainly of a tobacco blend , paper , PVA glue to bond the outer layer of paper together , and often also a cellulose acetate -- based filter . While the assembly of cigarettes is straightforward , much focus is given to the creation of each of the components , in particular the tobacco blend . A key ingredient that makes cigarettes more addictive is the inclusion of reconstituted tobacco , which has additives to make nicotine more volatile as the cigarette burns .
Endoplasmic reticulum
Manufacture of lysosomal enzymes with a mannose - 6 - phosphate marker added in the cis - Golgi network . Manufacture of secreted proteins , either secreted constitutively with no tag or secreted in a regulatory manner involving clathrin and paired basic amino acids in the signal peptide . Integral membrane proteins that stay embedded in the membrane as vesicles exit and bind to new membranes . Rab proteins are key in targeting the membrane ; SNAP and SNARE proteins are key in the fusion event . Initial glycosylation as assembly continues . This is N - linked ( O - linking occurs in the Golgi ) . N - linked glycosylation : If the protein is properly folded , Oligosaccharyltransferase recognizes the AA sequence N X S or N X T ( with the S / T residue phosphorylated ) and adds a 14 - sugar backbone ( 2 - N - acetylglucosamine , 9 - branching mannose , and 3 - glucose at the end ) to the side - chain nitrogen of Asn .
Mass production
Crossbows made with bronze parts were produced in China during the Warring States period . The Qin Emperor unified China at least in part by equipping large armies with these weapons , which were equipped with a sophisticated trigger mechanism made of interchangeable parts . Ships of war were produced on a large scale at a moderate cost by the Carthaginians in their excellent harbors , allowing them to efficiently maintain their control of the Mediterranean . The Venetians themselves also produced ships using prefabricated parts and assembly lines many centuries later . The Venetian Arsenal apparently produced nearly one ship every day , in what was effectively the world 's first factory which , at its height , employed 16,000 people . Mass production in the publishing industry has been commonplace since the Gutenberg Bible was published using a printing press in the mid-15th century .
Genetic recombination
In genetic engineering , recombination can also refer to artificial and deliberate recombination of disparate pieces of DNA , often from different organisms , creating what is called recombinant DNA . A prime example of such a use of genetic recombination is gene targeting , which can be used to add , delete or otherwise change an organism 's genes . This technique is important to biomedical researchers as it allows them to study the effects of specific genes . Techniques based on genetic recombination are also applied in protein engineering to develop new proteins of biological interest .
Base pair
In 1989 Steven Benner , then at the Swiss Federal Institute of Technology in Zurich , and his team led with modified forms of cytosine and guanine into DNA molecules in vitro . The nucleotides , which encoded RNA and proteins , were successfully replicated in vitro . Since then , Benner 's team has been trying to engineer cells that can make foreign bases from scratch , obviating the need for a feedstock .
Hard disk drive
The voice coil itself is shaped rather like an arrowhead , and made of doubly coated copper magnet wire . The inner layer is insulation , and the outer is thermoplastic , which bonds the coil together after it is wound on a form , making it self - supporting . The portions of the coil along the two sides of the arrowhead ( which point to the actuator bearing center ) then interact with the magnetic field of the fixed magnet . Current flowing radially outward along one side of the arrowhead and radially inward on the other produces the tangential force . If the magnetic field were uniform , each side would generate opposing forces that would cancel each other out . Therefore , the surface of the magnet is half north pole and half south pole , with the radial dividing line in the middle , causing the two sides of the coil to see opposite magnetic fields and produce forces that add instead of canceling . Currents along the top and bottom of the coil produce radial forces that do not rotate the head .
Phosphene
Phosphenes have also been created by intense , changing magnetic fields , such as with transcranial magnetic stimulation . These fields can be positioned on different parts of the head to stimulate cells in different parts of the visual system . They also can be induced by alternating currents that entrain neural oscillation as with transcranial alternating current stimulation . In this case they appear in the peripheral visual field . This claim has been disputed ; the alternative hypothesis is that current spread from the occipital electrode evokes phosphenes in the retina . Phosphenes created by magnetic fields are known as magnetophosphenes .
Virus
Viral populations do not grow through cell division , because they are acellular . Instead , they use the machinery and metabolism of a host cell to produce multiple copies of themselves , and they assemble in the cell . A
Cell nucleus
Gene expression first involves transcription , in which DNA is used as a template to produce RNA . In the case of genes encoding proteins , that RNA produced from this process is messenger RNA ( mRNA ) , which then needs to be translated by ribosomes to form a protein . As ribosomes are located outside the nucleus , mRNA produced needs to be exported .
Cell wall
Many protists and bacteria produce other cell surface structures apart from cell walls , external ( extracellular matrix ) or internal . Many algae have a sheath or envelope of mucilage outside the cell made of exopolysaccharides . Diatoms build a frustule from silica extracted from the surrounding water ; radiolarians , foraminiferans , testate amoebae and silicoflagellates also produce a skeleton from minerals , called test in some groups . Many green algae , such as Halimeda and the Dasycladales , and some red algae , the Corallinales , encase their cells in a secreted skeleton of calcium carbonate . In each case , the wall is rigid and essentially inorganic . It is the non-living component of cell . Some golden algae , ciliates and choanoflagellates produces a shell - like protective outer covering called lorica . Some dinoflagellates have a theca of cellulose plates , and coccolithophorids have coccoliths .
Bessemer process
High - quality steel was made by the reverse process of adding carbon to carbon - free wrought iron , usually imported from Sweden . The manufacturing process , called the cementation process , consisted of heating bars of wrought iron together with charcoal for periods of up to a week in a long stone box . This produced blister steel . The blister steel was put in a crucible with wrought iron and melted , producing crucible steel . Up to 3 tons of expensive coke was burnt for each ton of steel produced . Such steel when rolled into bars was sold at £ 50 to £ 60 ( approximately £ 3,390 to £ 4,070 in 2008 ) a long ton . The most difficult and work - intensive part of the process , however , was the production of wrought iron done in finery forges in Sweden .
Plant virus
Some viruses use the production of subgenomic RNAs to ensure the translation of all proteins within their genomes . In this process the first protein encoded on the genome , and this the first to be translated , is a replicase . This protein will act on the rest of the genome producing negative strand sub-genomic RNAs then act upon these to form positive strand sub-genomic RNAs that are essentially mRNAs ready for translation .
Origin of replication
Many bacteria , including E. coli , contain plasmids that each contain an origin of replication . These are separate from the origins of replication that are used by the bacteria to copy their genome and often function very differently . For example , the E. coli plasmid pBR322 uses a protein called Rop / Rom to regulate the number of plasmids that are within each bacterial cell . The most common origin of replication that is used in plasmids for genetic engineering is called pUC . This origin is derived from pBR322 but it contains two mutations . One single point mutation in the origin itself and another that deletes the Rop / Rom gene . This removes all the regulatory constraints on the plasmids replication and the bacteria then go from producing 30 -- 40 plasmids per cell with pBR322 up to producing over 500 with pUC . This allows genetic engineers to produce large quantities of DNA for research purposes . Other origins of replication include pSC101 ( derived from Salmonella , around 5 copies per cell ) , 15A origin ( derived from p15A , 10 -- 20 copies per cell ) and Bacterial artificial chromosomes ( 1 copy per cell ) .
Western blot normalization
The normalization control is a protein that , ideally , is expressed constantly at the same level across different experimental conditions . As such , housekeeping genes and proteins are often used as internal normalization standards in quantitative PCR ( qPCR ) and western blots . These proteins were designated as housekeeping because they are essential for the maintenance of basic cellular functions and are universally expressed in all cells of an organism . Some examples of classically used housekeeping proteins include ß - Actin , GAPDH , HPRT1 , and RPLP1 . Until recently , these proteins were considered to be expressed at a consistent , stable level under normal or pathophysiological conditions in any cell or tissue type . However , recent studies have shown that expression of housekeeping proteins can change across different cell types and biological conditions . It is critical to carefully validate any housekeeping protein chosen as a normalization standard against the sample type and experimental condition . Although normalization reagents ( such as antibodies against key proteins ) are common and effective , HKP expression can be impacted by experimental conditions . As a result , normalization control must be validated .
Tooth decay
Four things are required for caries formation : a tooth surface ( enamel or dentin ) , caries - causing bacteria , fermentable carbohydrates ( such as sucrose ) , and time . This involves adherence of food to the teeth and acid creation by the bacteria that makes up the dental plaque . However , these four criteria are not always enough to cause the disease and a sheltered environment promoting development of a cariogenic biofilm is required . The caries disease process does not have an inevitable outcome , and different individuals will be susceptible to different degrees depending on the shape of their teeth , oral hygiene habits , and the buffering capacity of their saliva . Dental caries can occur on any surface of a tooth that is exposed to the oral cavity , but not the structures that are retained within the bone .
Gene
In all organisms , two steps are required to read the information encoded in a gene 's DNA and produce the protein it specifies . First , the gene 's DNA is transcribed to messenger RNA ( mRNA ) . Second , that mRNA is translated to protein . RNA - coding genes must still go through the first step , but are not translated into protein . The process of producing a biologically functional molecule of either RNA or protein is called gene expression , and the resulting molecule is called a gene product .
Cell membrane
The oolemma of oocytes , or egg cells , are not consistent with a lipid bilayer as they lack a bilayer and do not consist of lipids . Rather , the structure has an inner layer , the fertilization envelope , and the exterior is made up of the vitelline layer , which is made up of glycoproteins ; however , channels and proteins are still present for their functions in the membrane .
Antigen-presenting cell
After dendritic cells have phagocytosed pathogens , they usually migrate to the vast network of lymph vessels and are carried by lymph flow to the draining lymph nodes . Each lymph node is a collection point where APCs can interact with T cells . During the migration , DCs undergo a process of maturation : they lose most of their ability to further engulf pathogens and they mature by changing surface expression of MHC and co-stimulatory molecules , as well as increased production of cytokines . The internalized antigen is digested into smaller peptides containing epitopes , which are then presented to T cells by the MHC .
Spark plug
Because the spark plug also seals the combustion chamber of the engine when installed , seals are required to ensure there is no leakage from the combustion chamber . The internal seals of modern plugs are made of compressed glass / metal powder , but old style seals were typically made by the use of a multi-layer braze . The external seal is usually a crush washer , but some manufacturers use the cheaper method of a taper interface and simple compression to attempt sealing . Metal
Virus
Prolate This is an icosahedron elongated along the fivefold axis and is a common arrangement of the heads of bacteriophages . This structure is composed of a cylinder with a cap at either end .
DNA replication
All cellular life forms and many DNA viruses , phages and plasmids use a primase to synthesize a short RNA primer with a free 3 ' OH group which is subsequently elongated by a DNA polymerase . The retroelements ( including retroviruses ) employ a transfer RNA that primes DNA replication by providing a free 3 ′ OH that is used for elongation by the reverse transcriptase . In the adenoviruses and the φ29 family of bacteriophages , the 3 ' OH group is provided by the side chain of an amino acid of the genome attached protein ( the terminal protein ) to which nucleotides are added by the DNA polymerase to form a new strand . In the single stranded DNA viruses -- a group that includes the circoviruses , the geminiviruses , the parvoviruses and others -- and also the many phages and plasmids that use the rolling circle replication ( RCR ) mechanism , the RCR endonuclease creates a nick in the genome strand ( single stranded viruses ) or one of the DNA strands ( plasmids ) . The 5 ′ end of the nicked strand is transferred to a tyrosine residue on the nuclease and the free 3 ′ OH group is then used by the DNA polymerase to synthesize the new strand .
Atom
Elements heavier than iron were produced in supernovae through the r - process and in AGB stars through the s - process , both of which involve the capture of neutrons by atomic nuclei . Elements such as lead formed largely through the radioactive decay of heavier elements .
Fermentation
Heterolactic fermentation , where some lactate is further metabolized and results in ethanol and carbon dioxide ( via the phosphoketolase pathway ) , acetate , or other metabolic products , e.g. : C H O → CH CHOHCOOH + C H OH + CO If lactose is fermented ( as in yogurts and cheeses ) , it is first converted into glucose and galactose ( both six - carbon sugars with the same atomic formula ) : C H O + H O → 2 C H O Heterolactic fermentation is in a sense intermediate between lactic acid fermentation , and other types , e.g. alcoholic fermentation ( see below ) . The reasons to go further and convert lactic acid into anything else are :
Cytosol
Another large class of protein compartments are bacterial microcompartments , which are made of a protein shell that encapsulates various enzymes . These compartments are typically about 100 - 200 nanometres across and made of interlocking proteins . A well - understood example is the carboxysome , which contains enzymes involved in carbon fixation such as RuBisCO .
Bird nest
The cup nest is smoothly hemispherical inside , with a deep depression to house the eggs . Most are made of pliable materials -- including grasses -- though a small number are made of mud or saliva . Many passerines and a few non-passerines , including some hummingbirds and some swifts , build this type of nest . Cup