What are 'Enzymes'?

Enzymes Enzymes are proteins and are biological catalysts. They speed up chemical reactions that happen within living things. They are very efficient at doing their job. To give you an idea of efficiency one catalase molecule can break six million hydrogen peroxide molecules into harmless water and oxygen per minute. There are two types of enzymes extracellular enzymes and intracellular enzymes. Extracellular enzymes are made inside cells, once formed they may move out and do its job outside of the cell an example of extracellular enzymes is the enzymes in the digestive system. Intracellular enzymes are also produced inside the cell, however they work within the cell speeding up the chemical reactions they can also control reactions. An example of an enzyme-controlled reaction is: Maltase (enzyme) Maltose (substrate) Glucose (product) The substance that the enzyme acts on (Maltose) is called the substrate. The new substance(s) formed is called the product(s). This reaction, along with many metabolic reactions, is reversible meaning maltose can become glucose or glucose can become maltose. They way the reactions turns depends on the proportions of glucose to maltose. If there is a lot of maltose and little glucose then the reaction will be as above but if there is less maltose than glucose then it will go

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  • Level: AS and A Level
  • Subject: Science
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What are 'Enzymes'?

Enzymes Enzymes are catalysts. Most are proteins. (A few rib nucleoprotein enzymes have been discovered and, for some of these, the catalytic activity is in the RNA part rather than the protein part. Link to discussion of these ribozymes.) Enzymes bind temporarily to one or more of the reactants of the reaction they catalyses. In doing so, they lower the amount of activation energy needed and thus speed up the reaction. Examples: * Catalyse. It catalyses the decomposition of hydrogen peroxide into water and oxygen. 2H2O2 -> 2H2O + O2 One molecule of catalyse can break 40 million molecules of hydrogen peroxide each second. * Carbonic anhydrase. It is found in red blood cells where it catalysis the reaction CO2 + H2O <-> H2CO3 It enables red blood cells to transport carbon dioxide from the tissues to the lungs. One molecule of carbonic anhydrase can process one million molecules of CO2 each second. * Acetylcholinesterase. It catalysis the breakdown of the neurotransmitter acetylcholine at several types of synapses as well as at the neuromuscular junction - the specialized synapse that triggers the contraction of skeletal muscle. One molecule of acetyl cholinesterase breaks down 25,000 molecules of acetylcholine each second. This speed makes possible the rapid "resetting" of the synapse for transmission of another nerve impulse. Most of these interactions

  • Word count: 635
  • Level: AS and A Level
  • Subject: Science
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Too Much Information: Genetic Testing

Too Much Information: Genetic Testing Biology OAC ISP Essay - By Daniel Perez Genetic testing offers a whole new world of information about us and how our bodies work. The data we get from delving into our own genetic code can help us to cure or even prevent disease, stop medical conditions such as cancer or cystic fibrosis from even manifesting, or even correct these sorts of errors before birth, and many other beneficial uses. However, at this point in time, all of this is beyond us. We have no miracle cures, no 'magic bullet' with which to fight disease or genetic conditions, in fact, our understanding of the genetic code is so limited that it's as if we cannot see the forest for the trees. We have taken our first baby steps into understanding human genetics with the completion of the Human Genome Project, and now that we have the big picture, we can begin to interpret it. Through information gleaned from our DNA, we now know that there are certain medical conditions that are caused by certain patterns within the genes. Some examples of these genetic conditions include Tay-Sach's disease, Bloom syndrome, Deafness, cystic fibrosis, and many other diseases (http://www.einstein.edu/e3front.dll?durki=7158). Although many of these conditions are fatal, the ones that are not can be treated early, even before symptoms develop when possible, or if not treated, at least monitored

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  • Level: AS and A Level
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Visit report

Visit report Garson's Farm *Aspect 1 the main aspect:- GM crops *Aspect 2 :- Pesticides *Target audience:- AS and A Level Biology students * Word count 1,892 Introduction Garson's farm is a family owned farm that is situated in London. The farm started off growing vegetables for the small markets in London. When the supermarket chains took over there was a higher demand for mass fruit and vegetables which led to the small markets and small shops losing business and shutting down. The bigger industrial farms sold their fruit and vegetables to the new supermarkets and Garson's farm could not compete with big demands. This led to the farm looking for other ways to keep their farm business going. This led to the idea of pick your own fruit. Garson's farm has been successful pick your own fruit farm now for over 25 years. (1) On our visit to Garson's farm our tour guide and part owner of the farm spoke of some of the many problems of growing fruit and crops in general for farmers. Examples of these are, having to deal with crops and fruit killing diseases that attacks the plants as well as other pests. Bob Garson said "that it is almost imposable for the farm to go completely organic because of the disease that now exist in the soil from the many years of growing plants on the same piece of land." Another reason it is hard for farms to become completely organic and

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  • Level: AS and A Level
  • Subject: Science
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What affects the kinetic energy of a trolley?

What affects the kinetic energy of a trolley? In this experiment I will be trying to see if the amount a spring is compressed affects the speed of a Trolley when released against the trolley. I'll be using a 'light gate' attached to a time to help me to find out how fast the trolley passes the light gate out, from this I will be able to figure out the speed and how much Kinetic energy the trolley has. Plan Aim: To see if the amount a spring is compressed by affects the speed of the trolley pushed by the spring. I will also be looking to see if I can find any patterns in the results I get and see if there is any way I can predict what. Variables: Independent Variable: In this experiment I will have only one independent variable, which I will change though out the experiment. The independent variable will be how much the spring is compressed, each time I compress the spring I will increase it by another centimetre until I have done it from 1 - 15 cm. From this I should be able to see if there is a regular increase in the speed the trolley travels at when I increase the amount that the spring is compressed by. Dependent Variables: I'll have several Dependent variables in this experiment to try and help keep it a fair test. The first one being that I'll keep all the other variables the same (e.g. Mass and Distance). I'll also make sure that I use all the same

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  • Level: AS and A Level
  • Subject: Science
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Use of a Redox Indicator to show Dehydrogenase Activity

Use of a Redox Indicator to show Dehydrogenase Activity Hypothesis: As the temperature increases, the time taken for the colour change to occur will decrease. Introduction: Triphenyl tetrazolium chloride (also known as T.T.C) is an example of an artificial hydrogen acceptor. It is a redox indicator which is colourless when oxidised, however when reduced, it produces a red, insoluble precipitate called 'formazans'. T.T.C can therefore be used to investigate the enzyme activity of dehyrogenase enzymes by showing a colour change when they are present. The purpose of this experiment is to see what effect temperature has on the activity of dehydrogenase enzymes within yeast cells. Materials/Apparatus: * Actively respiring yeast suspension. This is prepared by adding 10g of dried yeast to 1dm3 of distilled water, followed by mixing in 50g of glucose. This mixture should be allowed to stand for 24 hours before the experiment takes place. * Tiphenyl tetrazolium chloride is used as a redox indicator to investigate the activity of dehydrogenase enzymes when yeast suspension is exposed to different temperatures. * Distilled water for the preparation of the yeast suspension. * Test tubes to place the mixture of yeast and T.T.C. * Test tube rack to allow the test tubes to stand upright in the water baths. * Incubator to allow enzyme activity to occur at different temperatures *

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What is Homeostasis?

HOMEOSTATSIS Homeostasis is a very important biological function that occurs in all endotherms but not ectotherms. Endotherms have the ability to adjust their body temperature: they are not dependent on the surrounding temperature of the environment. Examples of endotherms are mammals: humans. Homeostasis works by using a process called negative feedback which works by adjusting a condition in the body so that the internal environment stays, on average, the same. It works using nerves. A receptor detects the change in the surrounding environment and sends nerve impulses to the centres in the brain, such as the medulla, which sends nerve impulses to glands or muscles to bring about an effect which will lower or increase a condition in the internal environment to keep it within certain limits. Homeostasis is used to control body temperature, blood glucose concentration and the water content of the blood. The body temperature in endotherms is controlled by dilation and contraction of arterioles, sweat and contraction of the erector pili muscles. This is called thermoregulation. When the temperature of the surrounding environment increases the internal environment must be decreased. To do this the arterioles dilate (vasodilation) so that more blood flows through the capillaries next to the skins surface. This means more heat can be released through the skin as the blood is

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  • Level: AS and A Level
  • Subject: Science
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What is Homeostasis?

Homeostasis is involved in keeping the body's internal environment constant (like the thermostat of a central heating system). Homeostasis keeps the body's temperature at a certain level (36.5oC) and it keeps the pH of the body at a certain level so that enzymes don't denature. Blood glucose is kept constant, CO2 levels and O2 levels are monitored to ensure that enough oxygen and not too much carbon dioxide are in the blood. The overall concentration and volume of blood is also monitored homeostatically. The term Homeostasis was first used by Cannon in the late 1920s. Homeostasis is very important to animals because it allows them to rely on the external environment. A constant internal environment allows a considerable degree of independence and allows animals to live in areas from the arctic to the tropics. Many of the mechanisms involved rely on negative feedback. A movement from the set level (e.g. a rise or fall in body temperature) is detected by receptors. These receptors then send information to the control centre in the brain which reacts by returning to the original value. For example, the temperature control mechanism. Humans maintain body temperature within 1oC of 36.5. If the temperature rises too high, the resulting increase in blood temperature is detected by receptors in the hypothalamus in the brain. The heat loss centre also in the hypothalamus sends

  • Word count: 1604
  • Level: AS and A Level
  • Subject: Science
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What is resistance?

PLANNING What is resistance? Electricity is conducted through a conductor; in this case it is conducted through a wire through means of free electrons. The number of free electrons depends on the material. The more free electrons the better the conductor is. For example, gold has more free electrons than iron therefore gold is the better conductor. The greater the resistance tin a circuit the less current that flows. A variable resistor is able to control the amount of current that flows through a circuit. Increasing the length of wire will increase the resistance. Ohms Law is when the voltage is directly proportional to the current. This means that when the voltage is doubled the current is doubled as well and if the voltage was cut in half the current would cut in half as well. The symbols used in ohms law are V for volts, R for resistance, measured in ohms, and I for the current, measured in amps. The equation V=IR is used to work out the Voltage; I=V/R is used to calculate the current; and R=V/I to calculate the resistance. Predictions I think that the longer the wire is the higher the resistance will be. This is because the longer the wire the more times the free electrons will collide with other free electrons and the particles and impurities that make up the metal. Fair Test To make this experiment fair I will have to make sure that: * The length of

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  • Level: AS and A Level
  • Subject: Science
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What do You Understand by Recombinant DNA Technology?

What do You Understand by Recombinant DNA Technology? Discuss the Moral, Ethical, Social, Economic and Environmental Issues Associated with the Technology, giving your views. There are two essential substances found inside bacterial cells required before the process can begin. Present in the cytoplasm of a bacterial cell are a number of small circular pieces of DNA known as plasmids. Also present within the bacterial cell are restriction enzymes which cut DNA molecules at specific sites. By selecting the correct restriction enzyme, DNA molecules from different organisms can be cut at predictable sites to extract specific genes from lengths of DNAi. The first task in the process is to isolate the required gene. This can be done in three different ways; working backwards from the protein, using messenger RNA, or using DNA probes. Once the gene has been isolated, the next step is to cut the gene from its DNA chain. This is done using the restriction enzymes (restriction endonucleases). Now we have the required gene the next stage is to insert it into a vector which will be used to produce the required protein. This is where the plasmids described earlier come in (this could also be done using a virus as a vector). The plasmid is cut using the same restriction enzyme as was used to cut the gene out. In a process called ligation (controlled by the ligase enzyme) the ends of the

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  • Level: AS and A Level
  • Subject: Science
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