• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Biology coursework

Extracts from this document...


Investigating the effect of bead diameter on conversion of sucrose to glucose and fructose by immobilized invertase Hypothesis- I predict that as the invertase beads decrease in diameter, the rate of glucose production will increase. Background Biology Enzymes are protein molecules, which serve to accelerate the chemical reactions of living cells. Without enzymes, most biochemical reactions would be too slow to even carry out life processes. Enzymes display great specificity and are not permanently modified by their participation in reactions. Since they are not changed during the reactions, it is cost-effective to use them more than once. However, if the enzymes are in solution with the reactants and/or products it is difficult to separate them. Therefore, if they can be attached to the reactor in some way, they can be used again after the products have been removed. Specificity Enzymes are usually very specific as to which reactions they catalyze and the substrates that are involved in these reactions. Complementary shape, charge and hydrophilic/hydrophobic characteristics of enzymes and substrates are responsible for this specificity, which is often referred to as "the lock and key" model. Immobilized enzymes An immobilized enzyme is an enzyme that is physically attached to a solid support over which a substrate is passed and converted to product. There are a number of advantages to attaching enzymes to a solid support and a few of the major reasons are listed below: * Multiple or repetitive use of a single batch of enzymes * The ability to stop the reaction rapidly by removing the enzyme from the reaction solution (or vice versa) * Speedy separation of products reduces feedback inhibition * Product is not contaminated with the enzyme (especially useful in the food and pharmaceutical industries) * Analytical purposes - long 1/2-life, predictable decay rates and elimination of reagent preparation * Thermal stability is increased allowing higher temperatures to be used * Higher operating temperatures increase rate of reaction When immobilizing an enzyme to a surface, it is most important to ...read more.


The reason I have chosen to use 17 minutes is that after preliminary trialling, I discovered this was the ideal time to leave the beads to harden and that they would produce the best results after this time. * I will ensure that I use the same beaker, measuring cylinder and pipette dimensions throughout my experiment. Although I could use many instruments to take measurements, I will always use the same ones to make sure that the experiment is fair. * I will always be using the same brand of Diabur 5000 test strips to measure how much glucose there is in the bead and sucrose mixture and I will always take down the results in mmol/litre as this will produce the most creditable results. * I will also make sure that the test strips are used every 30 seconds for 5 minutes with every bead size as this will ensure the results are fair. I will time the reaction using a stop clock, taking readings every 30 seconds without pausing the stop clock for any reason. * I will always mix the chemicals such that the sodium alginate will always go into the beaker before the invertase and they will always be stirred with a glad rod to ensure equal distribution. * I will always measure 10 beads of each size, using the micrometer as this will help me to work out a sensible average. It will also make the experiment more fair and plausible because the results will not be based on only one bead coming from each nozzle as even beads from the same nozzle may very considerably in size. * Finally, I will make sure that all the glassware, measuring cylinders, pipettes, nozzles, syringes, strainer and glass rod are thoroughly washed with tap water and then distilled water each time I use them. Risk Assessment Calcium Salts Calcium Chloride Calcium chloride is an irritant; wear goggles to protect eyes; avoid inhalation and raising dust. ...read more.


The 210mm is also shown on the next page. Another important factor is the various limitations involved in drawing a conclusion from a single investigation. The use of 5 different nozzle sizes, though perhaps sufficient for my investigation, is not sufficient for drawing a firm conclusion. This is because a lack of further investigation prevents the more extensive results, which would be required in order to assert a conclusion. Overall it would appear that my investigation does support my hypothesis that as the beads decrease in size, the rate of reaction will increase. In regard to further work, I would need far more different nozzles of distinguishably different diameters in order to come to a definite conclusion. In addition, carrying out more repeat tests would help ensure the experiment was more reliable and this may lead to a better end result. I also faced a problem in that the colours shown on the Diabur test strips are of course limited and I had to assume the colour according to the scale I had. However, it might have been a good idea to decide on a value for colours in between the values I was given. This may have made the data more reliable as well as providing a higher degree of accuracy. Finally, I could have used pH buffers in order to ensure the pH of every solution was exactly the same. This would have made the test more fair and perhaps given more accurate results. For this particular investigation I used yeast-derived invertase but had more time been available, it would have also been profitable to investigate a wider range of invertase enzymes, perhaps derived from different sources. Furthermore, I used the method of immobilizing the enzymes by entrapping them within a gel to form the sodium alginate beads. However, there are a variety of other ways I could have done this: * Carrier-Binding: the binding of enzymes to water-insoluble carriers * Cross-Linking: intermolecular cross-linking of enzymes by bi-functional or multi-functional reagents. * Covalent bonding to a solid support * Encapsulation behind a selectively permeable membrane ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    The Effect Of pH On Invertase Activity.

    3 star(s)

    Oppositely, Benedict solution would not change colour since denatured invertase was not able to catalyze the hydrolysis of sucrose to produce glucose. 5 test tubes were collected and labeled (2, 4, 7, 9 , 11) with a water soluble pen.

  2. Marked by a teacher

    Biology Coursework Investigation

    3 star(s)

    - The temperature of enzyme (input variable) - This is another input variable which if changed will alter your overall results. This is due to the fact that enzyme activity increases as temperature increases, until an optimum temperature is reached; then the activity rapidly decreases until the enzyme no longer works.

  1. Affect of sucrose concentration on the rate of respiration.

    But the disadvantages of this source of information were that it only displayed brief definitions on the topics and does not explain in detail on the main points of the topic. Evaluating all the secondary sources I used I found the best source being the textbooks.

  2. A2 coursework- The effects of bile salts on digestion of fat

    will change according to this. So it is important that the concentrations of the bile salts are the only variable changed in the experiment to gat reliable results. I will change the concentrations of the bile salt to the concentrations shown in the blow table.

  1. Catalyse Investigation

    The amount and time this acid was added was kept constant for each reading and so will not affect the accuracy of the results. iii) Substrate Concentration - When there is an excess of enzyme molecules, an increase in the substrate concentration, produces a corresponding increase in the rate of reaction.

  2. A Level Biology revision notes

    * Analysis o Rf = (distance moved by substance) / (distance moved by solvent) What are enzymes? * All enzymes are globular proteins � spherical in shape * Control biochemical reactions in cells * They have the suffix "-ase" * Intracellular enzymes are found inside the cell * Extracellular enzymes act outside the cell (e.g.

  1. Biology Coursework on Enzymes.

    intestine. Trypsin specifically catalyses the splitting of peptide bonds. Distilled Water- this is used in the control, the control consists of distilled water and caesin suspension. Test tubes and test tube rack- this is used to put the separate solutions in such as distilled water, Trypsin solution, pH buffer solution, etc.

  2. Osmosis Coursework

    so the mass will be lower than the original mass before the experiment. APPARATUS 1. Test tubes 2. 1 potato 3. 6mm potato borer 4. Knife 5. Cutting tile 6. Various sucrose solutions 7. Bungs 8. Pipette DATA REQUIRED 1.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work