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AS and A Level: Molecules & Cells

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  1. The application of enzymes in industry and medicine.

    However in the modern day mass production of bread relying purely on the natural enzymes is not enough. For example, on such a large scale the quality of the flour varies and is not good enough to produce large quantities of bread. Therefore more enzymes are used as supplements in the process. The enzymes used include; xlanase, ?-amylase, protease, glucose oxidase, and lipase. These enzymes are added into the dry flour and begin to work once the water is added to make the dough. These supplements allow a better handling of dough and a control of the end characteristics such as taste and crumb texture.

    • Word count: 717
  2. A basic introduction to spreadsheets.

    Q1. If I changed cell D3 to 400, then what number would appear in cell E3? �4, 000.00 Q2 If I changed the ticket price to �12 then what number would appear in cell E3? �4, 800 Now that you understand the basics of a multiplication formula then It's time to work out a few for yourself. The next screenshot just shows that at our club in fact some people got in on the guest list, some of the guests got in for a pound and some got in for half price.

    • Word count: 741
  3. To investigate the effect of pH on the ability of Catalase to breakdown Hydrogen Peroxide.

    Changing the pH will break the bonds in the enzyme. The active site will then lose its specific shape and substrates will no longer be able to bind with it and react. Changes in pH may also change the charge of the R groups in the active site. Background Info Changing the pH will break the bonds in the enzyme. The active site will then lose its specific shape and substrates will no longer be able to bind with it and react. Changes in the pH may also change the charge on the R groups, decreasing the affinity between substrate and the active site.

    • Word count: 656
  4. Investigation into the effect of temperature on the digestion of fat by Lipase.

    Before beginning the investigation on the digestion of fat by lipase I first carried out a preliminary experiment to discover how much Sodium Carbonate should be used- this is valid to the experiment because the amount of Sodium Carbonate will affect the amount of time taken. A shorter time would be more beneficial, to enable me to check results. Method: 1. Place the following into a test tube: 3cm Milk, 1cm Lipase. 3 drops phenolphalein. 2cm Sodium Carbonate. 2. Place test tube into a water bath at 38 3.

    • Word count: 859
  5. Human Physiology Osmosis.

    Active Transport There are many examples of materials passing through living cell membranes against a concentration gradient, i.e. passing from a low concentration to a high concentration. Transporting materials against a concentration gradient is called active transport and it requires an energy source of the work done. Active transport can only take place in living cells that contain an energy source called ATP. ATP is found inside cells, acting rather like a rechargeable battery, releasing energy when it is required and recharged from the energy released by the mitochondria of the cell. In some physiological circumstances, molecules may need to be moved very rapidly and accurate transport can be sussed here.

    • Word count: 801
  6. The application of enzymes in industry and medicine.

    how the enzyme-substrate complex works (the active site is exactly complementary to the shape of the substrate), the other is of an induced fit where the active site is not exactly complementary but as the substrate binds with the active site, the shape changes very slightly to form a perfect fit. The importance of enzymes is lowering activation energy (the amount of energy required for the reaction to occur), so that the chemical reactions necessary can proceed sufficiently quickly and within an acceptable temperature range. During catalysis, the enzyme will bind temporarily to one or more of the substrates (reactants)

    • Word count: 739
  7. Using Cell Phone.

    It is an impolite action if you leave your cell phone's ringing tone on when you are at a certain places that is inappropriate. The ringing sound can distract people when they are trying to concentrate on doing something else. Across the globe, cell phone's ringing sound disturbs when we are at a theater such as plays, concerts and films. For example, yesterday when I was watching a movie at Mission Valley Theater. I heard about three phone rings from the back of me. I felt really annoyed because the ringing sound distracted me from listening to the actor's conversation.

    • Word count: 682
  8. The effect of Temperature on the activity of an enzyme.

    The substrate in this experiment is milk, when trypsin is added, it will start digesting the protein in the milk and soon the milk will turn clear, this signals that the protein has been digested and is no longer present. Prediction I predict that as the temperature gets higher, the activity of an enzyme will increase. This is due to the kinetic theory that when there is more energy (in this case heat) the molecules will move faster at a higher temperature so there will be more collisions, because there are more collisions, there is more chance of the enzyme hitting the substrate so it will get digester more quickly.

    • Word count: 701
  9. Investigate the effect of temperature on the enzyme Catalase.

    Collide with a sufficient amount of energy. 3. Collide in a specific orientation. Catalase serves to protect the cell from the toxic effects of hydrogen peroxide by catalyzing its decomposition into molecular oxygen and water without the production of free radicals (an atom or group of atoms with an unpaired electron, unusually reactive and are capable of causing a wide range of biological damage). Hydrogen Peroxide (2H2O2) + Catalase = Oxygen + Water METHOD: EQUIPMENT LIST: 1x Water Bath 2x Boiling Tubes 1x Conical Flask 1x 5ml glass vial 1x Measuring cylinder 2x Beakers 1x Ice cream tub (containing water)

    • Word count: 928
  10. To find out how is enzymes affect by different type of temperature and see the changes in the colour of the mixture of iodine, starch and amylase.

    Eventually the shape of the amylase molecule changes too much and the starch molecule will not be able to fit on at all. This means that the amylase will not be able to break down the starch at all and the reaction will not take place. With heat kinetic energy is created which gives the particles in the water more energy so therefore they have a higher chance of cliding and reacting with each other. As results this the starch will break down faster Science knowledge: As the temperature rises the enzyme works much quicker, but if it gets too hot, above 45�C the enzymes will denature.

    • Word count: 980
  11. How does temperature affect the rate of reaction between yeast and hydrogen peroxide?

    * Volume of yeast. * Volume of hydrogen peroxide * Blockers: this is where a competitive inhibitor goes into the active site of the enzyme thereby preventing the substrate from binding with the enzyme. * Its pH My chosen factor: The factor which I have chosen to do is the different temperatures which I react the two chemicals together. Prediction: I think that the higher the temperature is the faster the reaction will take place also the troth will get bigger when the chemicals are at a higher temperature.

    • Word count: 429
  12. Lipase Investigation.

    Sodium Carbonate makes the solution alkaline which is pink to start with but as more acids are produced the pH drops and the solution turns white. Prediction I predict that the higher the temperature, the less time the whole process will take. I think this because when there is more energy, each fat molecule will be able to find an enzyme faster so then the enzyme can break it down into fatty acids and glycerol. A higher temperature increases the amount of collisions between the substrate and the active site on the enzyme.

    • Word count: 926
  13. Absolute and Relative formula

    normal formula, this is because if you transfer it into another sheet it wouldn't work this is because in an absolute formula we put the $ sign before it. I will also be using absolute formula where I will need to display the same sums or totals in a different position on the page. Also when paste linking the $ formula is used to show that it is an absolute formula.

    • Word count: 592
  14. The similarities and differences between prokaryotic and eukaryotic cells.

    Prokaryote means 'before the nucleus', which means the DNA isn't contained inside of the membrane. Prokaryotic cells have appeared in fossil records from 3500 million years ago and are made up of a variety of organisms known collectively as bacteria. Prokaryotic cells are smaller and less complex than eukaryotic cells. Prokaryotic cells have no nuclear membrane; the nuclear membrane is a very porous membrane that allows molecules to easily pass freely from the cytoplasm.

    • Word count: 563
  15. Investigation into the effect of substrate concentration on the activity of the enzyme catalase.

    This means that not all the active sites are in use resulting in a slow reaction rate, as collisions between the active site and the substrate molecules would be less frequent. Also, less gas would be evolved due to the small amounts of substrate with which the enzyme would react. However, if the concentration of the substrate were increased, due to the increased number of substrate molecules in the solution, collisions would be more frequent. This would mean an increased rate of reaction, as more of the enzyme molecules would be in use.

    • Word count: 861
  16. Discuss the Importance of the Structure and Function of Proteins to Living Organisms.

    The first structure that can be formed is the primary structure because it is the simplest. Successive amino acids form together in one long polypeptide chain. Theoretically there is no limit to the number of primary structured proteins. When the primary chain spirals upon itself, into a helical form it reaches a secondary structure. "This is a result of hydrogen bonding to form either an alpha helix, which is the most common form." ((c) UK-Learning 2002) Others that exist are beta-pleated sheets. Proteins that remain at the secondary level of structure are known as fibrous proteins.

    • Word count: 800
  17. Biology investigation to test for the presence of amylase in germinating seeds.

    The bean extract should be filter through a few layers of wet muslin cloth and centrifuged thoroughly so the any solid debris are being separated out. (4) The time duration for the experimental set-up and the control set-up should be the same. (5) An equal amount of starch solution should be used with the same concentration. (6) Distance between the table lamp and the vial should be kept the same as light intensity should be kept constant throughout the two experiments.

    • Word count: 853
  18. Find out how changing the temperature will affect the overall C02 production.

    I used a programme on the computer to carry out my experiment for maximum accuracy and controlled conditions, but the apparatus that would be needed to carry out the experiment would be a thermometer, a stop clock, a water bath, a , a and a once the apparatus is set up to do the experiment you have to have the water bath at a certain temperature to get your first result, the result being the amount of co2 given off from the yeast respiration, you should also

    • Word count: 590
  19. Roots are equal in importance to leaves as the life support system for plants.

    Root hairs may be long or short, dense, spares, or absent altogether. Root hairs are considered to help in direct mineral nutrient uptake by increasing the surface are of roots. Roots also require minerals. Most importantly they need nitrates. Nitrates from the soil are combined with carbohydrates from photosynthesis to make proteins. All proteins contain nitrogen. Plants get their nitrogen from nitrates. A plant with a shortage of nitrates will suffer from poor growth and yellow leaves. Another mineral required by plants is magnesium. Magnesium is needed to make chlorophyll. Magnesium deficiency leads to yellow leaves.

    • Word count: 756
  20. I am investigating the enzyme rennin, to see at which temperature it will clot the milk the quickest. Rennin is found in your stomach. It clots the milk that you drink so that it stays in your body longer.

    This investigation will be kept fair by using appropriate variables. The variable I am going to change is the temperature of the water. I will be keeping the amount of rennin and the amount of milk constant. The only variable that could cause a problem is the water temperature. Some of the results will need to be repeated for the lower temperatures because when they heat up past their desired temperature it is harder for it to cool down because room temperature, for example is above 20 degrees.

    • Word count: 563
  21. To investigate a certain factor that will affect the rate of breakdown of the protein gelatine using trypsin.

    and Size of photographic film (using a ruler). Prediction: I think that the trypsin (pH9) will work best around 35 ?C. Explanation of prediction: Trypsin is an enzyme that breaks down proteins into amino acids. It is made in the gall bladder and works in the small intestine. The photographic film has a black protean gelatine coating and trypsin breaks down proteins so therefore will break down the coating and the film will just become a clear strip of plastic.

    • Word count: 642
  22. To find out how temperature affects amylase.

    Then the amylase will no longer catalyse the breakdown of starch. This is because amylase is made up of protein molecules and therefore it is easily denatured by heat, losing its shape and no longer able to combine with the starch. I think the rate of breakdown of the starch will increase until this point because the increase in temperature will supply the molecules with more energy to react, and then it will slow down and the rate of reaction will be a lot longer. Apparatus: * Bunsen burner * Tripod * Gauze * Beaker * 2 test tubes * 2 spotting tiles * Pipette * Thermometer * Test tube rack

    • Word count: 740
  23. Investigating the effect of temperature on the action of trypsin.

    the beaker * The amount of alkaline buffer in the test tube * The person who times the experiments Prediction: I predict that the further away from 37degrees the temperature is, the longer the photographic film will take to go clear. This is because trypsin is found as an enzyme, which breaks down proteins into amino acids in the small intestine. 37degrees is body temperature. That is why it is more effective at that temperature. There will be the slowest reaction at 10degrees.

    • Word count: 929
  24. Functions Of Cell Membranes.

    Facilitated Diffusion - Certain important molecules such as the glucose sugar needed to provide energy to all cells can be transported through the membrane in a process called facilitated diffusion. Protein channels help to move the molecules down the concentration gradient from areas of high concentration to low. Active Transport - In some cases the concentration of molecules is greater on one side of the membrane than the other, but the cell still needs to move even more molecules through the membrane, against the concentration gradient.

    • Word count: 992
  25. Nerve Impulses.

    There are more charged proteins and potassium ions (K+) inside the axon than outside and more sodium ions (Na+), chloride ions (Cl-) outside the axon than inside. This imbalance produces an electrical gradient that is required to create a resting potential. The membrane is selectively permeable to different ions and it allows sodium. Potassium and chloride ions to diffuse freely across it. Larger charged proteins are restricted to the inside of the membrane by their size. Potassium ions inside the axon outnumber the sodium ions 10:1 and sodium ions outside the axon membrane always outnumber potassium ions 10:1.

    • Word count: 640

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