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AS and A Level: Molecules & Cells

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  1. The effect of Electromagnetic Fields on Enzyme Activity

    These are produced by any object whose temperature is above absolute zero (-273 C ). Infra-red rays have many uses in our society, they are, in fact, utilized by fire-fighters to search for unconscious people, or by doctors to detect circulation problems and cancers. Lastly we encounter Radio waves which have the longest wavelength and the lower frequencies on the spectrum. Radio waves are the ones which interest us the most for this research. They are categorized in five groups: Microwaves, Ultra High Frequency waves, Very High Frequency waves, Medium waves and long waves. Microwaves have the highest frequency and are used in microwave ovens, for communication with satellites and for radars.

    • Word count: 9710
  2. Observing the Rate of Reaction of the enzyme Catalase upon changing Concentrations

    Generally, there is only one active site on each enzyme molecule and only one type of substrate molecule will fit into it. This specificity leads to the lock and key hypothesis. However, it has been discovered that competitors for an active site (similar in shape to the substrate) could fit even though they are larger than the substrate. This means that the substrate and active site are a little flexible. Catalase is an enzyme found in food such as potato and liver.

    • Word count: 1225
  3. How Temperature Affects the Rate of Reaction of an Enzyme

    Enzymes are biological catalysts made up from protein. As we know, catalysts are substances that speed up the rate of a reaction without itself being used up. An enzyme has an active site, which has a unique shape into which only a substrate of the exact same unique shape can fit. Enzymes can be denatured at certain conditions. These conditions are high temperatures and extreme levels of pH. The bonds that hold enzymes together are quite weak and so are easily broken by the above conditions. When these bonds are broken the enzyme, along with the active site, is deformed, thus deactivating the enzyme.

    • Word count: 1428
  4. To find out how the rate of reaction of yeast can be increased

    The products in my investigation are CO, energy and alcohol. All enzymes are proteins and they have molecules with a very precise three-dimensional shape, containing an active site and also they are damaged by temperature above 40'c. I will look into this because in my investigation I'm looking at the temperature. Also most chemical reactions happen when the temperatures are high. At higher temperatures molecules move around faster, which makes it easier to react successfully. I use the word successfully because when they collide they need enough energy to work; if they don't have enough energy then nothing will happen.

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  5. Investigate how temperature affects the rate of anaerobic respiration in a sucrose & yeast solution.

    High temperature for instance will deform the active site & denature the enzyme. They work as follows: As with all other enzymes the enzymes in yeast are also affected by temperature & pH levels. I know this from both secondary and first-hand sources. Earlier in the year, I conducted numerous experiments whilst studying digestion, including investigations of both the action of pepsin and amylase. My results were as follows:- Investigating Temperature and the Action of Amylase: I set up test tubes filled with amounts of starch and amylase solution and then put each in a water bath, one at room temperature and one at 37�C.

    • Word count: 1868
  6. To see what effect temperature has on the speed of enzyme activity.

    We must then heat the water to the right temperature (Experiment 1: 20�C, Experiment 2: 80�C, Experiment 3: 40�C) and after about 5 minutes at the right temperature we will pour the milk into the Rennin. Following that we will check the mixture every minute until the milk has set as a gel. This means that our results won't be very accurate, as we will only be able to give the time to the nearest minute. Fair Testing: In this experiment there is only one variable, and that is the temperature of the water in the glass beaker. Everything else will remain as a constant: the amount of milk, the amount of Rennin, the amount of water in the beaker and how often we check to see if the milk has turned into a gel.

    • Word count: 766
  7. The effect of the concentration of the substrate on an enzyme.

    The way the substrate fits into the enzyme can be described in two ways; Firstly the lock and key mechanism, the substrate is the key and the enzyme is a lock, the two fit together perfectly. However recently a new hypothesis has been put forward this is called the induced fit, this states that the enzyme changes shape when the substrate molecule binds to the active site. The substrate and active site aren't perfectly matched until the substrate has bound to the active site because the binding of the substrate causes a change in the shape of the active site.

    • Word count: 1535
  8. The Effect On Respiration of Yeast At Different Temperatures.

    The bung to the test tube has a tube linked onto it, which I placed into a beaker of tap water. There was a range of tube sized to choose from but I used the smallest possible tube, again to get the most reliable results as possible because there will be more bubbles and they will be nearer the same size. I placed the yeast filled test tube into a water bath. These baths were spread across the classroom and were at different temperatures.

    • Word count: 810
  9. Factors That Affect The Rate Of An Enzyme Reaction.

    This reaction is extremely important, as hydrogen peroxide (which is extremely dangerous) is turned into water and oxygen through decomposion and sped up due to the catalase which acts as a catalyst. the equation for this reaction is: hydrogen peroxide ï® oxygen + water 2H2O2 ï® O2 + 2H2O An enzyme is the name of a protein that speeds up reactions.

    • Word count: 315
  10. Catalyse Investigation

    The more oxygen, the more catalyse activity and the less oxygen, the less catalyse activity. I will be able to measure the oxygen using the measuring cylinder. I will be using pureed potato to provide the enzymes for this experiment. This is the best kind of potato to use because it has more surface area than whole potatoes and this means more active sites for the substrate to react with.I will be change the enzyme concentration(amount of pureed potato) in order to measure its effects on the rate of catalyse activity. I will perform the experiment using 0cm3, 1cm3, 2cm3, 3cm3, 4cm3, 5cm3 of pureed potato.

    • Word count: 16451
  11. What Makes An Oil Runny?

    To make the experiment safe we all wore safety goggles and were careful not to expose the oil to a naked flame. We also ensured that we didn't get Hypothesis My hypothesis is that a body passes through a thick oil more slowly than a thin oil. Therefore the larger molecules are the less runny or more viscous. To support this theory I give the following examples C8H18 is a liquid and C32H68 is a solid. This helps to support my theory because the structure of the C32H68 is the same, just longer than C8H18 so the longer molecule of

    • Word count: 727
  12. What Affects The Action Of Catalase Enzyme On The Decomposition Of H2O2?

    The substrate fits into the active site to temporarily form a 'enzyme-substrate complex' this is where the reaction takes place, the enzyme then releases the product molecule and moves on to another molecule to repeat the process. Each enzyme has a different shaped active site and so can only work for one type of reaction. Enzymes can both put together and split apart molecules but I am just concentrating on their dividing properties in the reaction between Catalase and Hydrogen Peroxide.

    • Word count: 2096
  13. Experiment to Investigate the effect of the size of Applie Pieces used on the Yield of Juice Produced by Apples Using the Enzyme Pectinase

    The volume of apple juice obtained from the apple pieces in each beaker was recorded at 5 minute intervals for 40 minutes and recorded in a table. RESULTS AND CONCLUSION The results table above shows that by the end of the 40 minute course of my experiment, beaker A (containing the pectinase) produced 14 ml3 of apple juice and beaker B (containing the distilled water) didn't produce any apple juice. If the apple pieces were left to filter for longer, I am sure that eventually some juice would have been produced from beaker B, however the main aim of

    • Word count: 2626
  14. Investigation – the Effect of Enzyme Concentration On the Rate of Activity of Amylase

    (From a Greek term meaning "in yeast;" early studies of enzymes often involved reactions in yeast enzymes.) Amylase is an enzyme that is present in both saliva and pancreatic juices. Its function is to speed and aide the hydrolysis of amylose and another chemical, amylopectin into a mixture of products including dextrin and maltose. Because of my knowledge on enzymes and what they do and how they do it, I can suggest that the higher the concentration, the quicker the speed of the break down of starch will take place: If there are more enzymes (amylase molecules) than substrate (starch)

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  15. Investigating the effect of copper sulphate on the rate of reaction

    The most unique property is the need for an active site to mirror that precisely of a particular substrate molecule (this has become know as the lock and key model). This site allows a substrate to bond to the enzyme to form an enzyme substrate complex the active site is usually in the form of a cleft or depression. Temporary chemical bonds form between the substrate and some the R groups of the enzymes amino acids. Other groups of atoms within the active site speed up the chemical reaction of a substrate.

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  16. The effect of temperature on Membrane Permeability

    iv. Cut 10 of the cylinder beetroot pieces into lengths of 5cm v. When the distilled water has reached a temperature of 85oC place one of the beetroot cylinders into the water for one minute, then into the test tube marked 85 for 30 minutes. vi. While you are waiting for the 30 minutes to expire repeat step five using the remaining beetroot cylinders at the following temperatures: 80oC, 75oC, 70oC, 65oC, 63oC, 60oC, 55oC 50oC and 45oC place the cylinders into their corresponding test tube and leave each for 30 minutes. vii.

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  17. An Experiment Into How Temperature Affects the Activity of a Enzyme - Catalase and Potatoes

    Enzymes: * are proteins * are produced by cells * are 'specific' which means that each enzyme will only work on one substance * work best at a particular temperature (around 30-40 �C for digestive enzymes) called their 'optimum temperature' * work best at a particular ph called their 'optimum pH' At a temperature that is too high the structure of an enzyme ill be changed so that it will not work. Once the enzyme has passed this temperature the process is irreversible and the enzyme is said to be 'denatured.'

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  18. The effect of temperature on the rate of an enzyme catalysed reaction

    The enzyme molecule begins to lose its shape and activity and becomes denatured. This proves beyond doubt that this experiment was not accurate or fair and these results are undeniably incorrect. It must also be noted that although this is the optimum temperature according to the graph, it is also the most anomalous point on line. Lying furthest away from the line of best fit. Analysis Of Results As you can see from the processed results in the table above and the graph the experiment carried out was not the most accurate.

    • Word count: 1400
  19. Biology -The Effect of Temperature on Enzymes

    I took great care with the experiment because I was dealing with hot liquids. Apparatus * 27 photographic strips (substrate), each measuring 0.5cm x 35 mm * 3ml protease (trypsin) * Wire * Test tubes * Water bath * Thermometer * Stopwatch/timer Method I measured the time taken for the film to become transparent at different temperatures - this demonstrates whether or not the effectiveness of the enzymes increases or decreases with heat. I first switched on the water bath, setting it to 35�C. I then measured out 3ml of trypsin into the test tube, placing it upright into the water bath.

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  20. Investigating The Effect of Substrate Concentration or Temperature On The Rate of Decomposition of Hydrogen Peroxide By Catalase In Immobilised Yeast

    Safety As Hydrogen peroxide is a highly corrosive substance it is very necessary to wear protective eyewear and a lab coat and try to be extra careful when measuring out this substance The yeast and the hydrogen peroxide are harmful to the body so I think it would be wise to wash my hands after I have completed my experiment. As ever I will abide by all the lab safety rules Fair Test In my preparation of the alginate beads it is important to make sure that I pick a uniform size for the alginate ball as if they are

    • Word count: 2289
  21. Respiratory System Homework

    Thorax volume decreases and the air is forced out of the lungs. Air is forced in the rib cage and sternum drop in and down, then the air is forced out the thorax and finally to force the air out of the thorax the diaphragm moves up. Describe the jobs of red and white blood cells and explain how these are carried out.

    • Word count: 418
  22. Investigating the permeability of plant cells.

    All membranes have this basic structure, which is shown in the diagram, Figure 1. Membranes are held together by very strong covalent bonds, as well as the large number of weak interactions resulting from properties of lipids and water which give the membrane its strength, and at the same time flexibility. In membranes the lipids are amphipathic, I.e., they have two sides to their nature. They are predominantly hydrophobic because of the tail part but have a hydrophilic head portion which is attracted to water. The head of the phoshpholipid is hydrophilic because its phosphate group and the terminal alcohol are charged and interact easily with water.

    • Word count: 5710
  23. Investigating the affect of soaking on catalase activity in red kidney beans

    If these variables were not kept constant the results cannot be compared accurately. I will also repeat each experiment 3 times. This is so that any inaccuracies can be noticed. Apparatus Pan balance, 2cm cubed syringe, 10cm cubed syringe, 50cm cubed measuring cylinder, tub (for water bath), delivery tube, 15 test tubes, 3 test tube racks, clamp stand, spatula, thermometer, blender, filter paper, funnel, conical flask, 200ml beaker, 15ml beaker, weighing boat, stop watch, pH 7 buffer, red kidney beans (contains enzyme, catalase), hydrogen peroxide (substrate), and water. Background Information Enzymes are biological catalysts.

    • Word count: 1482
  24. Enzymes Investigation

    The enzyme itself is unaffected by the reaction. When the products have been released, the enzyme is ready to bind with a new substrate. The temperature and ph level affects enzymes. Uses of Enzymes Alcoholic fermentation and other important industrial processes depend on the action of enzymes that are produced by the yeasts and bacteria used in the production process. A number of enzymes are used for medical purposes. Some have been useful in treating areas of local inflammation; trypsin is employed in removing foreign matter and dead tissue from wounds and burns.

    • Word count: 1634
  25. Effect that the temperature has on the rate at which the Amylase (enzyme) can breakdown its starch (substrate)

    This is because the enzyme can not catalyse the reaction as the shape of the active site has become distorted therefore it can no longer combine with the substrate this is known as "lock and key " theory. I also predict that the more amylase (controlled variable) there is the quicker the reaction will take I know this because amylase catalyses the hydrolysis of starch. Preliminary Work Preparing the calibration curve experiment 1. Switch on the colorimeter to warm it up.

    • Word count: 1118

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