AcharyaChanakya/simple-wikipedia huggingface dataset:
In 1934, the Swiss pharmaceutical company Hoffmann-La Roche was the first to mass-produce synthetic vitamin C, under the brand name of Redoxon.
Main producers today are BASF/ Takeda, Roche, Merck and the China Pharmaceutical Group Ltd of the People's Republic of China.
In living organisms, ascorbate is an antioxidant, since it protects the body against oxidative stress. It is also a cofactor in at least eight enzymatic reactions, including several collagen synthesis reactions that cause the most severe symptoms of scurvy when they are dysfunctional. In animals, these reactions are especially important in wound-healing and in preventing bleeding from capillaries.
Lack of ascorbic acid in the daily diet leads to a disease
called scurvy, a form of avitaminosis that is characterized by:
A healthy person on a balanced western diet should be able to get all the vitamin C needed to prevent the symptoms of scurvy from their daily diet. People who smoke, those under stress and women in pregnancy have a slightly higher requirement.
The amount of vitamin C needed to avoid deficiency symptoms and maintain health has been set by variously national agencies as follows:
Some researchers have calculated the amount needed for an adult human to achieve similar blood serum levels as Vitamin C synthesising mammals as follows:
High doses (thousands of mg) may result in diarrhoea, which is harmless if the dose is reduced immediately. Some researchers (Cathcart) claim the onset of diarrhoea to be an indication of where the body’s true vitamin C requirement lies.
The small size of the ascorbic acid molecule means the kidneys cannot retain it in the body. Quite a low level in the blood serum will cause traces to be present in the urine. All vitamin C synthesising mammals have traces in the urine at all times.
In April 1998 "Nature" reported alleged carcinogenic and teratogenic effects of excessive doses of vitamin C. This was given great prominence in the world's media. The effects were noted in test tube experiments and on only two of the 20 markers of free radical damage to DNA. They have not been supported by further evidence from living organisms. Almost all mammals manufacture their own vitamin C in amounts equivalent to human doses of thousands of milligrams per day. Large amounts of the vitamin are used in orthomolecular medicine and no harmful effects have been observed even in doses of 10,000 mg per day or more.
Vitamin C is needed in the diet to prevent scurvy. It also has a reputation for being useful in the treatment of colds and flu. The evidence to support this idea, however, is ambiguous and the effect may depend on the dose size and dosing regime. The Vitamin C Foundation recommends 8 grams of vitamin C every half hour to show an effect on cold symptoms.
Fred R. Klenner, a doctor in Reidsville, North Carolina reported in 1949 that poliomyelitis yielded to repeated megadoses of intravenous vitamin C.
Nobel Prize winning chemist Linus Pauling began actively promoting vitamin C in the 1960s as a means to greatly improve human health and resistance to disease.
A minority of medical and scientific opinion continues to see vitamin C as being a low cost and safe way to treat infectious disease and to deal with a wide range of poisons.
A meta-study of the published research claimed that relatively high levels of vitamin C must be maintained in the body for it to function effectively as an antioxidant.
Some research shows that there are veterinary benefits of vitamin C as well.
One meta-study of the published research examined the effectiveness of ascorbic acid in the treatment of infectious disease and toxins. It was conducted in 2002 by Dr. Thomas Levy, Medical Director of the Colorado Integrative Medical Center in Denver. It claimed that overwhelming scientific evidence exists for its therapeutic role.
Some vitamin C advocates say that vitamin C is not used therapeutically because it cannot be patented. Pharmaceutical companies seek to generate revenue and profit their shareholders. They may be reluctant to research or promote something that will make them little money.
Dichlorphenolindophenol
DCPIP (its full name is "2,6-dichlorophenolindophenol") is a blue chemical used as a dye because when it is oxidized it is blue. Once DCPIP is reduced (by addition of electrons) it does not have a color anymore. This reaction can be reversed, and the colourless DCPIP will turn blue again, when it is oxidized.
DCPIP is often used to measure the electron transport chain in plants. It has a higher redox potential (electron affinity) than the Fe-S complex in cytochrome b and will therefore "steal" electrons from it. This means that cytochrome c does not receive them. The process cuts off the electron supply of photosystem I. A common way to illustrate this change is by the addition of vitamin C solution. This reduces the 'jelly' by transforming it to a colourless mass. This experiment can be carried out to illustrate the effect of changing cell sizes on SA/V (surface area:volume ratio). This is known as Titration.
Healthy diet
A healthy diet or balanced diet is a diet (what you eat) that contains the right amounts of all the food groups. It includes fruit, vegetables, grains, dairy products, and protein. It does not include too much or too little of any kind of food. Eating wrong amounts of a food group, whether it be too much or too little, is called an "unhealthy diet" or an "imbalanced diet". A healthy diet is one that includes more foods that come from plants and fewer convenience foods.
What is known about nutrition and diet keeps changing as more is learned. However, basic nutrition remains much the same. The best advice is to talk to a doctor or dietitian for personalized information based on an individual's lifestyle, health, and food likes and dislikes.
Dye is a substance used to color materials. It is often used to color the fabric used to make clothing. It has low solubility. A pigment won't do this because it won't stick to the fibers of the fabric and color them. A dye can be natural, usually made from plant material such as berries, or artificial, meaning that it is made by humans from chemicals such as petrochemicals.
Most natural dyes are gotten from different parts of a plant like the roots, fruits, bark, leaves, wood, fungi and lichens. Most dyes are synthetic and are made from petrochemicals.
Dyes can be classified based on their solubility and chemical properties.
Poetry is a type of art form and a type of literature.
Poetry uses the qualities of words, in different ways, to be artistic.
Poetry can be as short as a few words, or as long as a book. A poem as short as one line is called a monostich. A poem that is as long as a book is an epic.
There are many "poetic forms" (forms of poetry). Some of forms are: Sonnet, Haiku, Ballad, Stev, Prose poem, Ode, Free verse, Blank verse, thematic, limerick and nursery rhymes.
Poetry can be used to describe (comparing, talking about, or expressing emotion) many things. It can make sense or be nonsense, it can rhyme or not. It can have many shapes and sizes; it can be serious or funny.
"To say something poetically" means to give information in an artistic way.
A more modern approach is digital poetry. Computers and webtechnology is used to express poetry and make it interactive. So called interdisciplinary poetry (wich means combination of different forms of poetry) are made possible by linking the poetic texts with audio, video or web-animation (e.g. with CSS) or among themselves via hyperlinks. Modern artists use digital poetry to not only express artistic intention, but also to design a layout around their texts. An example for this use of interdisciplinary art, which combines abstract text and abstract visuals is the german project "Schwarzer Flamingo". It uses digital poetry to collect pieces of written art but also to give different artists a plattform. So some projects of digital art can be described as a form of an artwork as well as an exhibition.
Literature is a group of works of art made up of words. Most are written, but some are passed on by word of mouth. Literature usually means works of poetry and prose that are especially well written. There are many different kinds of literature, such as poetry, plays, or novels. They can also be put into groups through their language, historical period, origin, genre, and subject. The word "literature" comes from the Latin word "learning, writing, grammar".
Most of the earliest works were epic poems. Epic poems are long stories or myths about adventures. "Ramayana" and "Mahabharta", two Indian epics, are still read today. "Odyssey" and "Iliad" are two famous Greek poems by Homer. They were passed down through speaking and written down around the 8th century BC.
Literature can also mean imaginative or creative writing, which is looked at for its artistic value.
Imagination is a way to have fun, Imagination can also cause distress.
Bolus
In biology, a bolus (from the Latin word for "ball"), is a ball-shaped living thing.
In medicine, a "bolus" is a large amount of a drug given to patients to raise the blood level before treatment.
A "bolus" can also refer to a ball of food after it has been chewed. It passes down the oesophagus by peristalsis.
Oesophagus
The oesophagus (or esophagus) is also called the gullet. It is the part of the gastrointestinal system between the mouth and the stomach. It connects the pharynx and the stomach. It is about long.
The oesophagus is lined with muscle, and is lubricated. Its muscle pushes food down into the stomach. The oesophagus can contract or expand to allow for the passage of food. The muscular movement that pushes the food down the oesophagus is called peristalsis. At the entrance to the stomach there is a ring of muscle called a sphincter. This is usually closed, but relaxes as food approaches, allowing it to enter the stomach. In the stomach, the food is churned until it turns into a soupy mixture called chyme.
Protease
A protease is a digestive enzyme. It breaks down long chains of proteins into shorter amino acids. Proteases have evolved a number of times. We know this because different kinds of protease can do the same reaction in completely different ways. Proteases are found in animals, plants, bacteria, archaea and viruses.
Now more than 50 types of protease are known. Each is a separate evolutionary origin of proteolysis.
Protease can be divided into 6 types :
Dental floss is a special type of thread. It is used for cleaning spaces between teeth which cannot be reached by toothbrushes. It is important to floss before brushing teeth and to floss at least once a day. Tooth brushing will not clean food that is packed between teeth. This 'food packing' can lead to unhealthy teeth and gums. Bacteria grow in this 'packed food' between teeth. These bacteria cause the surface of teeth (enamel) to break down. Then the teeth and gums and sometimes even the jaw can become seriously diseased.
These bacteria that come from the food on the teeth and between the teeth are called "plaque" or "bacterial plaque" and also can cause the gums to become less healthy. "Gingivitis" which means gum disease is one type of disease that flossing helps to prevent. Very serious diseases can start on the teeth and move to the bone of the jaw, damaging the jaw badly. Flossing your teeth reduces the danger of these serious diseases of the jaw bone. These hard-to-cure jaw bone diseases are called "periodontal disease".
Food that is trapped between the teeth can be uncomfortable and even cause pain. Some food is hard, for example meat, apple. Ground meat is soft and so is apple sauce. Chicken and turkey meat are hard and full of fibres and very often get trapped between the teeth. When hard food is trapped between the teeth it can cause discomfort and sometimes pain. When hard food is pressed by the teeth against the gum it can cause pain. Some people use toothpicks to try to remove trapped food from between the teeth and other people use dental floss to do this.
Dental floss can do most things that a toothpick can do but dental floss is much thinner than a toothpick and can thus get to places that most toothpicks cannot reach. So floss presumably does a better job at getting bits of food out from between the teeth, relieving discomfort and pain quicker.
When a person first starts flossing, bleeding can happen. This is normal and happens because teeth and gums that are not flossed are less healthy. It will stop as the teeth and gums get healthier with flossing.
Rickets
Rickets is a disease that happens in young children. It happens in children who do not get enough vitamin D and calcium. It causes larger spaces inside bones, and makes them dry, like sponges. It can make the legs curve toward each other (so the knees touch) or away from each other.
Rickets in adults is called osteomalacia.
The word "rickets" comes from the Greek word "rhakhis", which means "spine."
People need both vitamin D and calcium to make their bones strong.
Vitamin D helps the bones absorb (take up) calcium. Low vitamin D makes it hard to absorb calcium.
The human body makes vitamin D in the skin, from cholesterol. Then the liver changes vitamin D into calcitriol, which sends calcium from the blood into the bones. The bones need calcium to stay strong. However, the skin will not make vitamin D unless enough ultraviolet light shines on it. Sunlight contains ultraviolet light, so getting enough sun is one way of getting enough D.
People need calcium for calcification. Calcification uses calcium to help make bones bigger and stronger. Low calcium makes bones delicate and easier to break.
Rickets can be prevented if a person gets plenty of calcium and vitamin D.
The best way to do this is to get a lot of sunlight, and eat foods that have a lot of vitamin D and calcium in them. However, people who cannot get enough vitamin D and calcium this way can take supplements (vitamin pills that have calcium and vitamin D in them).
Foods that have a lot of calcium in them include:
Calcium is absorbed best by the bones when it is taken in amounts of 500 600 grams or less. Because of this, doctors suggest eating smaller amounts of foods with calcium in them, at different times in the day, instead of all at once.
There are three ways to get vitamin D: sunlight, foods, or supplements (vitamin pills that have vitamin D in them). However, many people cannot get enough vitamin D just from their diet.
There are only a few foods that have a lot of vitamin D in them. They include:
Breast milk may not have enough vitamin D in it to prevent rickets. Babies who are only breastfed, and not fed any other foods, may be given vitamin D drops to make sure they do not get rickets. However, this is not a significant risk if mothers and child have some exposure to sunlight. Children with dark skin are more likely to need additional vitamin D.
These things make a person more likely to get rickets:
Signs and symptoms of rickets include:
Bile
Bile or gall is a green-yellow fluid. It is secreted from the liver of most vertebrate animals, and is often stored in the gall bladder. Bile helps digest fat.
The components of bile are
The name "gall" comes from the Greek word "cholè" meaning green or yellow.
The term cholesterol and the illness cholera were named after gall.
Bile is also stored in bile ducts. Often after liver transplants, bile comes out of the body.
The dental pulp is the part in the center of a tooth. It is made up of living soft tissue and cells. It is surrounded by dentine and contains nerves and blood vessels.
Protoplasm
Protoplasm is an old term, which means the living substance that makes up a cell. It is no longer much used. Biologists prefer to talk about the cytoplasm and the cell nucleus.
In plant cells, it is surrounded by a cell wall. In animal cells, the whole cell is made of protoplasm, surrounded by a cell membrane. Protoplasm in living beings is made up of about 7580% water. However, this is rather misleading because the cytoplasm is full of structures called organelles, which do various tasks. The endoplasmic reticulum is the largest of these structures; there are many other organelles.
The word "protoplasm" was first used in 1846 by Hugo von Mohl to describe the substance in plant cells, apart from the cell wall, the cell nucleus and the vacuole. After the invention of the electron microscope it was clear that a living cell is much more complicated than von Mohl knew.
Amylase
Amylase is an enzyme which breaks down starch into sugars which the body can use.
More accurately, it is a family of similar enzymes which work in a wide range of animals, plants and fungi. There are two variants in humans: alpha-amylase, and gamma-amylase.
Alpha-amylase is a major digestive enzyme. Its optimum pH is 6.7–7.0. It is found in saliva and pancreatic juice. It takes starch chains and breaks them into smaller pieces with two or three glucose units. It can break down starch into maltose. It works in the mouth and stomach during digestion.
The gamma-amylase has most acidic optimum pH of all amylases because it is most active around pH 3. Therefore, it works best in the stomach, which does have an acidic pH.
Apparently, early humans did not possess salivary amylase. The closest evolutionary relatives of humans, chimpanzees and bonobos, have either one or no copies of the gene for producing salivary amylase. A duplication event of the AMY1 gene led to the production of amylase in the saliva. The same event occurred independently in rodents. This shows the importance of salivary amylase in organisms that eat relatively large amounts of starch.
Carbohydrates are a food source rich in energy. After the agricultural revolution, human diet began to rely more on plant and animal domestication in place of hunting and gathering. This shift marked the beginning of a diet composed of 49% carbohydrates as opposed to the previous 35% observed in Paleolithic humans. As such, starch became a staple of human diet. Humans that contained amylase in the saliva would benefit from increased ability to digest starch more efficiently and in higher quantities.
Not all humans have the same number of copies of the AMY1 gene. Populations which rely on carbohydrates have a higher number of AMY1 copies than populations that eat little starch. The number of AMY1 gene copies in humans can range from six copies in agricultural groups such as European-American and Japanese (two high starch populations) to only 2-3 copies in hunter-gatherer societies such as the Biaka, Datog, and Yakuts.
The correlation between starch consumption and number of AMY1 copies suggests that more AMY1 copies in high starch populations is caused by natural selection. It is a favorable phenotype for those individuals. Therefore, it is likely that having more copies of AMY1 in a high starch population increases fitness and produces healthier, fitter offspring. Geographically close populations with different eating habits possess a different number of copies of the AMY1 gene. This offers strong evidence that natural selection has acted on this gene.
Variegated leaf
A variegated leaf is a type of leaf.
A variegated leaf is useful in conducting experiments to show that chlorophyll is needed for photosynthesis to happen. They are also popular in horticulture.
The easiest of these experiments is to stain the places where starch is produced (starch is a more compact form of glucose).
Place the leaves in boiling water for six minutes to soften the cells, and then in ethanol (alcohol). When the leaves are drained of colour, spread them out on a flat surface. Soak the leaves in iodine and the green parts will turn blue/black and the non green parts will stay the yellowish brown colour of iodine liquid. The green parts contain starch, which makes iodine turn blue/black. The blue/black stain is what shows starch is present. You could take "before & after" photos to prove the black areas were green at the start.
Seam ripper
A seam ripper is a cutting tool. It is used for removing stitches in sewing and cutting open buttonholes made on a sewing machine. Sometimes it is also called a thread ripper.
The tool usually has a handle, shaft, and head. The head has two points: one flattened to form a pointed blade and the other forming a small point.
To use a seam ripper to remove sewn threads, the blade is placed underneath the thread to be cut. The thread slips down between the two points, and the tool is then lifted upwards allowing the blade to cut through the thread. Then the loose thread ends can be removed.
Plaque
Plaque: a word meaning a flat, plate-like object.
Pin cushion
Chemical cell
A chemical cell converts chemical energy into electrical energy. Most batteries are chemical cells. A chemical reaction takes place inside the battery and causes electric current to flow.
There are two main types of batteries - those that are "rechargeable" and those that are not.
A battery that is not rechargeable will give electricity until the chemicals in it are used up. Then it is no longer useful. It can be rightly called 'use and throw'.
A rechargeable battery can be "recharged" by passing electric current backwards through the battery; it can then be used again to produce more electricity. It was Gaston Plante, a French scientist who invented these rechargeable batteries in 1859.
Batteries come in many shapes and sizes, from very small ones used in toys and cameras, to those used in cars or even larger ones. Submarines require very large batteries.
An extremely important class of oxidation and reduction reactions are used to provide useful electrical energy in batteries. A simple electrochemical cell can be made from copper and zinc metals with solutions of their sulphates. In the process of the reaction, electrons can be transferred from the zinc to the copper through an electrically conducting path as a useful electric current.
An electrochemical cell can be created by placing metallic electrodes into an electrolyte where a chemical reaction either uses or generates an electric current. Electrochemical cells which generate an electric current are called voltaic cells or galvanic cells, and common batteries consist of one or more such cells. In other electrochemical cells an externally supplied electric current is used to drive a chemical reaction which would not occur spontaneously. Such cells are called electrolytic cells.
An electrochemical cell which causes external electric current flow can be created using any two different metals since metals differ in their tendency to lose electrons. Zinc more readily loses electrons than copper, so placing zinc and copper metal in solutions of their salts can cause electrons to flow through an external wire which leads from the zinc to the copper. As a zinc atom provides the electrons, it becomes a positive ion and goes into aqueous solution, decreasing the mass of the zinc electrode. On the copper side, the two electrons received allow it to convert a copper ion from solution into an uncharged copper atom which deposits on the copper electrode, increasing its mass. The two reactions are typically written
Zn(s) --> Zn(aq) + 2e
Cu(aq) + 2e --> Cu(s)
The letters in parentheses are just reminders that the zinc goes from a solid (s) into a water solution (aq) and vice versa for the copper. It is typical in the language of electrochemistry to refer to these two processes as "half-reactions" which occur at the two electrodes.
In order for the voltaic cell to continue to produce an external electric current, there must be a movement of the sulfate ions in solution from the right to the left to balance the electron flow in the external circuit. The metal ions themselves must be prevented from moving between the electrodes, so some kind of porous membrane or other mechanism must provide for the selective movement of the negative ions in the electrolyte from the right to the left.
Energy is required to force the electrons to move from the zinc to the copper electrode, and the amount of energy per unit charge available from the voltaic cell is called the electromotive force (emf) of the cell. Energy per unit charge is expressed in volts (1 volt = 1 joule/coulomb).
Clearly, to get energy from the cell, you must get more energy released from the oxidation of the zinc than it takes to reduce the copper. The cell can yield a finite amount of energy from this process, the process being limited by the amount of material available either in the electrolyte or in the metal electrodes. For example, if there were one mole of the sulfate ions SO on the copper side, then the process is limited to transferring two moles of electrons through the external circuit. The amount of electric charge contained in a mole of electrons is called the Faraday constant, and is equal to Avogadro's number times the electron charge:Faraday constant = F = Ne = 6.022 x 10 x 1.602 x 10 = 96,485 Coulombs/moleThe energy yield from a voltaic cell is given by the cell voltage times the number of moles of electrons transferred times the Faraday constant.
Electrical energy output = nFE
The cell emf E may be predicted from the standard electrode potentials for the two metals. For the zinc/copper cell under the standard conditions, the calculated cell potential is 1.1 volts.
A simple cell typically has plates of copper (Cu) and zinc (Zn) in dilute sulphuric acid. The zinc dissolves and bubbles of hydrogen appear on the copper plate. These hydrogen bubbles interfere with the passage of current so a simple cell can only be used for a short time. To provide a steady current, a depolarizer (an oxidizing agent) is needed to oxidize the hydrogen. In the Daniel cell, the depolarizer is copper sulphate, which exchanges the hydrogen for copper. In the Leclanche battery, the depolarizer is manganese dioxide, which oxidizes the hydrogen to water.
English chemist John Frederick Daniell developed a voltaic cell in 1836 which used zinc and copper and solutions of their ions.
Das Lied der Deutschen
Das Lied der Deutschen ("The Song of the German people"), also known as Deutschlandlied, ("The Song of Germany"), is a song written by Joseph Haydn and Hoffmann von Fallersleben. Part of this song is the national anthem of Germany (German National Anthem).
A line from this song, "Einigkeit und Recht und Freiheit" ("Unity and justice and freedom") is the motto of Germany.
The music was written by Haydn in 1797 as the anthem of Austria. It was called "Gott erhalte Franz den Kaiser" ("God protect our Emperor Franz"). The words which are used today were written by the poet August Heinrich Hoffman von Fallersleben in 1841.
Today, the first line "Germany, Germany above all" sounds too strong for some people, and is often misunderstood. Fallersleben wanted a united Germany when he wrote it. At that time, Germany was not one country, but many small countries. So "Germany above all" meant that the most important thing to do was to have a unified Germany. Also, the poet was in Heligoland, where people spoke German but were ruled by the British.
Fallersleben's music was very popular in Germany during the second part of the 19th century. This song was not a national anthem then, but a patriotic song supporting a united German state. In 1918, it replaced the anthem of the German Empire "Heil Dir im Siegerkranz" ("Praise to the war-winner"), when the Emperor Wilhelm II lost power at the end of the First World War. In 1921, a "fourth stanza", a new part or verse, was written by poet Albert Matthai with words about the difficult life in Germany at that time. This verse was rarely used.
During the time of Hitler, only the first part of the song was used. This was often followed by a Nazi party song. This offended the international audience as the first stanza supports Germany holding colonial powers in non-consenting nations.
After the Second World War, Germany was divided into two countries. In 1949, the new Western Germany tried to get a new song for the national anthem. Another song was chosen, written by poet Rudolf Alexander Schröder. It was not very popular. Finally, the third part of the Fallersleben song was made into the national anthem.
In the other part of Germany, the Eastern Germany, the words of poet Johannes R. Becher ("Auferstanden aus Ruinen" - "Re-built from the Ruins") were used with a song written by Hanns Eisler. It was not very popular, and from the 1970s the words were not sung, because of the line "Germany, [our] unified fatherland".
After East and West Germany united again in 1990, the Fallersleben song again became the national anthem of Germany but only the third part is used. Today, the first part of the song is popular with nationalist extremists.
A cavity is a hole.
It can also mean:
Evidence is something that is used to support an argument. It gives examples of why something is true.
For example, if someone come across a cup of spilled milk, that person could look for evidence as to how the milk was spilled. If hairs of a cat and paw prints were found on the ground, they could be evidence that a cat was the cause of the spilled milk. If a witness saw the cat spilling the milk, her testimony would also be evidence.
Dyadic
A dyadic is a math function that needs two things in order to give something out. Addition and multiplication are dyadic. Powers are also dyadic. There are many more functions that are dyadic.
Dyadic may specifically refer to:
A hill is a landform that is higher than the surrounding terrain and that is smaller than a mountain. Hill is a highland of much lower elevation than a mountain. Normally it is not as steep as a mountain. The surface of a hill is much more stable than that of a dune. Hill have long been used for hill forts.
An enzyme is a protein molecule in cells which works as a biological catalyst. Enzymes speed up chemical reactions in the body, but do not get used up in the process, therefore can be used over and over again.
Almost all biochemical reactions in living things need enzymes. With an enzyme, chemical reactions go much faster than they would without the enzyme. Other biocatalysts are catalytic RNA molecules, called ribozymes.
The substances at the start of a reaction are called substrates. The substances at the end of a reaction are the products. Enzymes work on the substrates, and turn them into products. The study of enzymes is called enzymology.
The first enzyme was found in 1833 by Anselme Payen.
There are thousands of different enzymes and each one is specific to the reaction which it catalyses. Enzymes have names which show what they do. Enzyme names usually end in –ase to show that they are enzymes. Examples of this include ATP synthase. It makes a chemical called ATP. Another example is DNA polymerase. It reads an intact DNA strand and uses it as a template to make a new strand.
One example of an enzyme is amylase, found in saliva. It breaks down starch molecules into smaller glucose and maltose molecules. Another kind of enzyme is lipase. It breaks down fats into smaller molecules, fatty acids and glycerol.d
The proteases are a whole class of enzymes. They break down other enzymes and proteins back into amino acids. Nucleases are enzymes that cut DNA or RNA, often in specific place in the molecule.
Enzymes are not only for breaking large chemicals into smaller chemicals. Other enzymes take smaller chemicals and build them up into bigger chemicals, and do many other chemical tasks. The classification below lists the main types.
Biochemists often draw a picture of an enzyme to use as a visual aid or map of the enzyme. This is hard to do because there may be hundreds or thousands of atoms in an enzyme. Biochemists can not draw all this detail. Instead, they use ribbon models as pictures of enzymes. Ribbon models can show the shape of an enzyme without having to draw every atom.
Most enzymes will not work unless the temperature and pH are just right. In mammals the right temperature is usually about 37C degrees (body temperature). The correct pH can vary greatly. Pepsin is an example of an enzyme that works best when pH is about 1.5.
Heating an enzyme above a certain temperature will destroy the enzyme permanently. It will be broken down by protease and the chemicals will be used again.
Some chemicals can help an enzyme do its job even better. These are called "activators". Sometimes, a chemical can slow down an enzyme or even make the enzyme not work at all. These are called "inhibitors". Most drugs are chemicals that either speed up or slow down some enzyme in the human body.
Enzymes are very specific. In 1894 Emil Fischer suggested that both the enzyme and the substrate have "specific complementary geometric shapes" that fit exactly into one another. This is often referred to as "the lock and key" model. However, this model fails to explain what happens next.
In 1958, Daniel Koshland suggested a modification to the lock and key model. Since enzymes are rather flexible structures, the active site is reshaped by interactions with the substrate. As a result, the substrate does not simply bind to a rigid active site. The amino acid side-chains of the active site are bent into positions so the enzyme does its catalytic work. In some cases, such as glycosidases, the substrate molecule also changes shape slightly as it enters the active site.
The general equation for an enzyme reaction is:
Enzymes lower the activation energy of a reaction by forming an intermediary complex with the substrate. This complex is called an enzyme-substrate complex.
For example, sucrase, 400 times the size of its substrate sucrose, splits the sucrose into its constituent sugars, which are glucose and fructose. The sucrase bends the sucrose, and strains the bond between the glucose and fructose. Water molecules join in and make the cleavage in a fraction of a second. Enzymes have these key features:
There are five main ways that enzyme activity is controlled in the cell.
Inhibitors can be used to stop an enzyme from binding to a substrate. This may be done to slow down an enzyme-controlled reaction. The inhibitors fit loosely or partially into the enzyme's active site. This prevents or slows down an enzyme-substrate complex being formed.
Denaturation is the "irreversible" alteration of an enzyme's active site, caused by an extreme change in temperature or pH. It will decrease the rate of reaction because the substrate molecule will not be able to fit into the active site, so products cannot be formed.
Cofactors, or coenzymes, are helper molecules which are needed to make an enzyme work. They are not proteins, and may be organic or inorganic molecules. Both types of molecules sometimes contain a metal ion at the centre, such as Mg, Cu, Mn or iron-sulphur clusters. This is because such ions may act as electron donors, and this is important in many reactions. The need of enzymes for various little helpers is the basic reason why animals, including ourselves, need trace elements and vitamins.
Enzymes have been classified by the "International Union of Biochemistry". Their Commission on Enzymes has grouped all known enzymes into six classes:
The individual enzymes are given a four-figure number which classifies them in the database.
Enzymes are used commercially for:
A mountain is a large natural rise of the Earth's surface that usually has a "summit" (the name for a mountain's top, which can also be called a peak). It is usually steeper and taller than a hill. Mountains are often thought of as being a hill which is larger than 600 metres (about 2,000 feet). However, some definitions say a mountain is a hill larger than 300 meters (about 1,000 feet).
The forming of a mountain is called orogeny. Mountains are formed when rock layers in the ground are pushed from opposite sides, and by being pushed, they push the crust up. A mountain range is a large group of mountains beside each other. There are three main ways a mountain may be made:
Fold mountains occur when two plates collide. The less dense continental crust "floats" on the denser mantle rocks beneath. The continental crust is normally much thicker under mountains, compared to lower lying areas. Rock can fold either symmetrically or asymmetrically. The upfolds are anticlines and the downfolds are synclines. The Jura Mountains are an example of fold mountains.
Folded mountains make up some of the highest mountains in the world. Folded mountains commonly form along boundaries, where 2 continents meet. Some really complex folds are in parts of the Andes, Alps, Himalayas, Appalachians, and Russia's Ural Mountains. These long mountain chains also show lots of signs of folding.
Block mountains are caused by faults in the crust: a seam where rocks can move past each other. When rocks on one side of a fault rise relative to the other, it can form a mountain. The uplifted blocks are block mountains or "horsts". The dropped blocks are called "graben". They can form extensive rift valley systems. This form of landscape can be seen in East Africa, the Vosges, the Basin and Range province of Western North America and the Rhine valley. These areas often occur when the regional stress is extensional and the crust is thinned.
Volcanoes are formed in one of these ways:
Examples of volcanoes include Mount Fuji in Japan and Mount Pinatubo in the Philippines. The magma does not have to reach the surface in order to create a mountain: magma that solidifies below ground can still form dome mountains, such as Navajo Mountain in the states of Utah and Arizona, in the United States.
Volcanic mountains form when molten rock erupts onto the Earth's surface. They can either form on land or in the ocean. The Cascade Range in Washington, Oregon and northern California is made of volcanoes. Some of the largest volcanoes are on divergent boundaries, which form the mid-ocean ridges. The mid-ocean ridges have big volcanic mountain chains that run through the Atlantic, Pacific and Indian Oceans. The mountains in the mid-ocean ridges can grow tall enough to create islands such as Iceland or the Azores.
Other volcanic mountains form over hot spots, pockets of magma beneath the crust which erupt onto Earth's surface. The Hawaiian Islands are the tops of really high volcanic islands that have formed over a hot spot on the sea floor. The main Hawaiian island is a volcano about above the ocean floor. Its base is about wide. Almost of this island is above sea level.
Dome mountains, like those in the Black Hills of South Dakota and the Adirondack Mountains of New York, are an unusual domish type of mountain that is formed when molten rock rises through the crust and push up the rock layers above it. This creates a circular dome on the Earth's surface. The molten rock later cools off and forms hardened rock. When the pushed up rocks are worn away, the hardened rock is shown. This hardened rock then wears away in places. When it wears away, it leaves mountains, and they are called dome mountains.
Plateau mountains are formed a bit like folded mountains. They are large areas of flat topped rocks that have been lifted high above the crust by continental plates. Most plateaus are near folded mountains.
The height of a mountain is measured as distance above sea level.
The highest known mountain in the Solar System is the Olympus Mons (27 km high) on Mars. The highest mountain on earth is Mount Everest (8,848m) which is in Nepal and Tibet, in Asia.
The "tallest" mountain in the world is Mauna Loa, in Hawaii. The "height" of a mountain is measured from sea level, but the "tallness" of a mountain is measured from its base, even if under water. The highest mountain in North America is Mount McKinley (6,194m) in Alaska in the USA. The highest in South America is Aconcagua (6,962m) in Argentina. For Africa, it is Kilimanjaro (5,963m) of Tanzania. In Europe, the highest mountain is in Russia called Elbrus (5,633m). Antarctica's highest mountain is Vinsin Massiff (5,140m). In Oceania, a mountain called Puncak Jaya (5,030m) is the highest there. This particular mountain is in Papua New Guinea / Indonesia.
Machine code
Machine code is a computer program written in machine language. It uses the instruction set of a particular computer architecture. It is usually written in binary. Machine code is the lowest level of software. Other programming languages are translated into machine code so the computer can execute them.
An instruction tells the process what operation to perform. Each instruction is made up of an opcode (operation code) and operand(s). The operands are usually memory addresses or data. An instruction set is a list of the opcodes available for a computer. Machine code is what assembly code and other programming languages are compiled to or interpreted as.
Program builders turn code into another language or machine code.
Machine code is sometimes called native code. This is used when talking about things that work on only some computers.
Machine code can be written in different forms:
There are many kinds of instructions usually found in an instruction set:
Many modern processors use microcode for some of the commands. More complex commands tend to use it. This is often done with CISC architectures.
Every processor or processor family has its own instruction set. Instructions are patterns of bits that correspond to different commands that can be given to the machine. Thus, the instruction set is specific to a class of processors using (mostly) the same architecture.
Newer processor designs often include all the instructions of a predecessor and may add additional instructions. Sometimes, a newer design will discontinue or alter the meaning of an instruction code (typically because it is needed for new purposes), affecting code compatibility; even nearly completely compatible processors may show slightly different behavior for some instructions, but this is rarely a problem.
Systems may also differ in other details, such as memory arrangement, operating systems, or peripheral devices. Because a program normally relies on such factors, different systems will typically not run the same machine code, even when the same type of processor is used.
Most instructions have one or more opcode fields. They specify the basic instruction type. Other fields may give the type of the operands, the addressing mode, and so on. There may also be special instructions that are contained in the opcode itself. These instructions are called "immediates".
Processor designs can be different in other ways. Different instructions can have different lengths. Also, they can have the same length. Having all instructions have the same length can simplify the design.
The MIPS architecture has instructions which are 32 bits long. This section has examples of code. The general type of instruction is in the "op" (operation) field. It is the highest 6 bits. J-type (jump) and I-type (immediate) instructions are fully given by "op". R-type (register) instructions include the field "funct". It determines the exact operation of the code. The fields used in these types are:
"rs", "rt", and "rd" indicate register operands. "shamt" gives a shift amount. The "address" or "immediate" fields contain an operand directly.
Example: add the registers 1 and 2. Place the result in register 6. It is encoded:
Load a value into register 8. Take it from the memory cell 68 cells after the location listed in register 3:
Jump to the address 1024:
Area is the amount of space a two dimensional (flat) surface takes up. It is useful because it is how much of a material is needed to make a hollow container. Area is the amount of surface covered by a close object or shape.
Small areas can be measured in square centimetre and large areas in square kilometre. The area of a planar figure is often written as formula_1. Areas of regular shapes such as square, rectangle, triangle and circle can be calculated through formulas. The area of an irregular shape can be approximated through grid or graph paper.
One can use different formulas to find the area of different shapes. For example:
The area of a flat object is related to the surface area and volume of a three-dimensional object.
The area under a curve can be found using integration, a concept from calculus.
Some units used to measure area are square foot, square mile, square metre and square kilometre.
Air space
Swamp cooler
Swamp coolers are simple type of air conditioning device that can cool a room of a house or a car by using the cooling effect of the evaporation of water. Swamp coolers can cool the air temperature in a small space by drawing the air through wet pads (some are made of aspen wood) using an electric fan.
Swamp coolers work best in dry climates such as the American Southwest and the American South. They are usually much cheaper to buy and operate than refrigerated air-conditioning devices.
This type of air conditioner was first used thousands of years ago in ancient Iran
Saskatoon
Saskatoon is a city in Saskatchewan, Canada. Saskatoon is the biggest city in Saskatchewan. Saskatoon, though, is not the capital of Saskatchewan. Regina is the capital of Saskatchewan. The South Saskatchewan River flows through the centre of the city and many people enjoy boating, biking and walking in this area. The University of Saskatchewan is also in Saskatoon.
The name "Saskatoon" [in Cree: "sâskwatôn", "Saskatoon"] comes from the Cree inanimate noun "misâskwatômina" "saskatoon berries", which refers to the sweet, violet-coloured berry that grows in the area.
Glass rod
Glass rods are sometimes used as stirrers in laboratory environments.
Glass rods are often used to spread liquids evenly onto something. An example would be to coat glass surfaces with liquids to look at them under a microscope.
Glass rods rubbed with silk or fur were used in early demonstrations of electrical energy.
Glass rods are commonly manufactured in diameters of 3 mm, 6 mm, and 10 mm.
Glass is used for these rods because it does not react with most laboratory chemicals.
A thermometer is an instrument for measuring or showing temperature (how hot or cold something is). One type of thermometer is a narrow, concealed glass tube containing mercury or alcohol which extends along the tube as it expands. Another type is a digital thermometer, which uses electronics to measure temperature.
Early thermometers from the time of Galileo measured the expansion and contraction of air. After the middle 17th century many used alcohol or mercury. In the 19th century a mechanical thermometer was in invented that used a bimetallic strip to move a pointer. This kind is still popular where people like to read temperature from a distance.
A laboratory thermometer is a tool used in laboratories to measure temperature with high accuracy. It can be partially or fully immersed in the substance being measured. A laboratory thermometer is recognizable by its long stem with a silver bulb at the end. The silver color in the bulb normally indicates the presence of mercury. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. Mercury-in-glass thermometers are less used in the 21st century as preference is shifted to other types of thermometers, such as digital, alcohol-filled and organic-based thermometers.
In the 20th century, the traditional clinical thermometer was a mercury-in-glass thermometer. People put the end of this in their mouth ("oral" temperature), under their arm, or in their rectum ("rectal" temperature).
It is only possible to find oral temperatures on patients who can hold the thermometer correctly in their mouth. So small children cannot use this method. It is also a problem for people with a cough or people who are vomiting. In the past it was a big problem because mercury thermometers needed a long time to measure the temperature. Today's digital thermometers are faster. If a person drinks something hot or cold, one still needs to wait before testing their oral temperature.
When measuring a person's rectal temperature, it helps to use a cream on the thermometer. Rectal thermometers are usually more reliable since they aren't as much influenced by other factors. In some countries people think it is embarrassing to use them for people older than two or three. In other countries, it is considered normal for children and adults to use rectal thermometers.
In the 1990s, people in many countries thought mercury thermometers were too risky, as mercury is dangerous if it leaks out. Today we use electronic thermometers. Sometimes thermometers with liquids are used, but not with mercury.
There are other kinds of medical thermometers: "tympanic" thermometers test the temperature of the tympanic membrane (the eardrum) with infrared; "band" thermometers test a person's temperature on the front of their head.