• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14
  15. 15
    15
  16. 16
    16

Enzyme theory: explore the properties and functions of enzymes

Extracts from this document...

Introduction

Introduction In this experiment I will attempt to investigate how the change in temperature effects the catalyse reaction and what the optimum temperature is. Key factors Key factor (variable) Reason for controlling How it is going to be controlled Temperature of hydrogen peroxide H202 I am going to control this variable because if the temperature of the hydrogen peroxide was higher or lower then the right temperature the test wouldn't be fair and my results could be affected because a different temperature would result in a different froth height. I am going to control the temperature by placing the hydrogen peroxide into a water bath with the exact temperature for at least 3 minutes. Temperature of yeast I am going to control this variable because if the temperature of the yeast was higher or lower than the right temperature the test wouldn't be fair and my results could be affected because a different temperature would result in a different froth height. I am going to control the temperature by placing the hydrogen peroxide into a water bath with the exact temperature for at least 3 minutes. Water temperature I am going to control this variable because if I didn't the hydrogen peroxide and the yeast will be at different temperatures because I will use the water to heat the hydrogen peroxide and yeast. I am going to control this variable by having the water placed in a water bath which will keep the water at a constant temperature. Volume of hydrogen peroxide I am going to control this variable because if I didn't my results would differ to the results I would have if my results where accurate and this wouldn't be a fair test. I am going to control this variable by using a pipette to pour the hydrogen peroxide into the small measuring cylinder (10cm3). Volume of yeast I am going to control this variable because if I didn't my results would differ to the results I would have if my results where accurate and this wouldn't be a fair test. ...read more.

Middle

At this point the enzyme is said to be denatured. With a fixed amount of enzyme the addition of more substrate will cause the rate of reaction to increase until all the enzyme molecules are being used. At this point the rate of reaction levels off because the enzyme is limiting the reaction. An increase in the amount of enzyme will cause a proportional increase in the rate of reaction provided that there is excess substrate. Enzymes work in a narrow range of pH outside of which the hydrogen bonds between the NH and CO groups are broken. A solution that prevents changes in pH is called a buffer solution. Scientific knowledge used to plan Structure in enzymes The different levels of protein structure are known as primary, secondary, tertiary, and quaternary structure. There are 20 common amino acids are classified by their functional group, or their "R" group. When the weak hydrogen bonds that help the enzyme take its shape break because of the heat the enzymes have become denatured. Primary structure The primary structure is the sequence of amino acids that make up a polypeptide chain. 20 different amino acids are found in proteins. The exact order of the amino acids in a specific protein is the primary sequence for that protein. AA1-AA2-AA3-AA4-AA5-AA6-AA7-AA8-AA9-AA10-AA11-AA12 etc This structure twists and turns because of the R groups in the amino acids. Every R group is different If you zoom in on one of the amino acids and look at the structure you will see: H H R NH3 - C - C - C - CooH H H R Because of the attraction between the r groups weak hydrogen bonds are formed, these bonds are what hold the structure together and if the enzyme its alpha helix or beta sheet shapes. Secondary structure The amino acids form regular repeating patterns folding along the protein back bone. ...read more.

Conclusion

This will only be so until the enzyme denatures after its optimum temperature Since enzymes are catalysts for chemical reactions, enzyme reactions also tend to go faster with increasing temperature. However, if the temperature of an enzyme catalysed reaction is raised still further, an optimum is reached: above this point the kinetic energy of the enzyme and water molecules is so great that the structure of the enzyme molecules starts to be disrupted. The positive effect of speeding up the reaction is now more than offset by the negative effect of denaturing more and more enzyme molecules. Many proteins are denatured by temperatures around 40 - 50�C, but some are still active at 70 - 80�C, and a few withstand being boiled. So, my first prediction is that the enzyme will become denatured at around 40�C, and secondly, that as the temperature increases the reaction rate will increase by 50%, due to the molecules colliding together at a higher speed (kinetic theory) due to their extra energy obtained by the increase in temperature. My prediction is supported by Kinetic Theory in that if I apply twice as much heat there will be twice as much particle vibration therefore the reaction will happen twice as quickly. It is also backed by Collision Theory in that if I apply twice as much heat there will be twice as many collisions and therefore the rate of reaction will double. This will only be so until the enzyme denatures after its optimum temperature: 45�C. On the next page there is a graph of what I think the actual graph of the results is going to look. From the graph you can see that the maximum froth height rises until it reaches its optimum temperature (40 oc) then the graph starts to fall. Secondary source data In this experiment I intend to use at least 1 other piece of data to check my results against I am also going to use a set of results from a computer program called focus education software. In total I am using 3 sets of data including mine. ...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

    An investigation to examine the effects of temperature on membrane stability in beetroot, by ...

    3 star(s)

    I placed 2cm cylinders of beetroot into boiling tubes containing; 4cm�, 6cm� and 10cm� distilled water, left them for 10 minutes and then tested the solutions in the colorimeter. Table to show the percentage of light able to pass through the solutions, which had contained different volumes of distilled water.

  2. Investigate the effect of enzyme temperature on the activity of the enzyme Trypsin on ...

    Other than the anomalies, I think my results were quite accurate and reliable as they followed the expected pattern and I carried out my procedure extremely efficiently that I had time to re-investigate the anomalies that occurred. The most likely explanation for the resulting anomalies was the inaccurate stirring regime.

  1. Investigate how concentration of the enzyme catalase in celery tissue alters the rate of ...

    at a stable rate, compared to the 100% which has a very steep line gradient. The volume and concentration of Hydrogen Peroxide never changed, so when the catalase was at 25% concentration there were many more hydrogen peroxide molecules per catalase molecule.

  2. Trypsin. Hypothesis: - I hypothesize that as the temperature increases the rate of enzyme ...

    Likewise if some particular experiment is allowed for less time the volume of oxygen produced will be less because than the enzyme Catalase will be able to breakdown less amount of hydrogen peroxide than it was broken down before, thus producing more oxygen.

  1. I am aiming to investigate the rate of reaction between pepsin, an enzyme and ...

    We will have beakers containing hot and cold water to add to them if needed to keep them at the required temperatures. We will be measuring the time it takes for each solution to turn clear, repeating the experiment three times, and then taking the averages.

  2. The effect of temperature on the action of the enzyme trypsin

    Also, it is important to remember that at high temperatures, enzymes work at accelerated speeds for short periods of time before denaturing (when the enzymes lose their 'key' shape so they cannot fit in the 'lock' of the substrate), whereby they are useless.

  1. Does Lowering Storage Temperature Increase the Reducing Sugar Content of Potatoes?

    -10�C), around (aprox. 5�C) and room temperature (aprox. 21�C). It is essential that these remain at the correct temperature throughout the week. Both a fridge and freezer are needed to keep the potato samples at the correct temperatures; these can be adjusted according to convenience.

  2. Investigating antimicrobial properties of plants.

    Wear rubber glove while removing the plant fibre from water to prevent bacterial infection because there are a lot of microorganism in the plant fibre as the pumpkin stem has undergone retting. Wash your hands after handling the soaked fibre.

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