Factors affecting enzyme activity

Question 1

What does Q10 stand for?

Answer 1

The temperature coefficient

Question 2

What is the equation for finding Q10 (the temperature coefficient)?

Answer 2

Rate at T+10/Rate at T

Question 3

Draw the graph showing the effect of temperature on enzyme activity

Answer 3

A graph which starts rapidly going up, has a peak, goes down quickly

Question 4

Explain why the rate of the reaction is fast in the beginning of the graph showing the effect of temperature on enzyme activity

Answer 4

1. As the temperature increases the kinetic energy of the enzyme and substrate molecules increases
2. This increases the number of successful collisions between the substrate and the enzyyme’s active site
3. This increases the number of enzyme-substrate complexes
4. This increases the rate of the reaction

part 1 and 2 for temperature have 4 points

Question 5

Explain why the rate of the reaction has a peak in the middle of the graph showing the effect of temperature on enzyme activity

Answer 5

1. At optimum temperature there is the maximum number of successful collisions between the enzyme active site and the substrate molecules
2. This means that there is the maximum number of enzyme-substrate complexes formed
3. Which means that there is a maximum rate of reaction
4. Typically for an enzyme controlled reaction, in this part of the graph Q10=2, which means that for each 10 degrees Celcius increase in temperature the rate of the reaction doubles

part 1 and 2 for temperature have 4 points

Question 6

Explain why the rate of the reaction decreases at the end of the graph which shows the effect of temperature on enzyme activity

Answer 6

1. After optimum temperature the enzymes denature
2. This is because as the temperature increases the kinetic energy of the enzyme molecules increases which causes the molecules to vibrate more rapidly
3. This disrupts the hydrogen bonds, ionic bonds and hydrophyllic/hydrophobic interations in the tertiary structure of the enzyme protein
4. This changes the shape of the enzyme molecule and its active site, which means that the shape of the active site is no longer complementary to the substrate
5. This means that no more enzyme-substrate complexes can be formed

in this point we are basically explaining 1) WHY the enzyme has denature after optimum temperature and 2) the EFFECT that this denaturing has on the enzyme activity and thus the rate of the reaction- this third part has 5 points instead of four, just ONE teensy extra one for you 😊😙

Question 7

Name the four factors which affect ezyme activity and thus the rate of an enzyme controlled reaction

Answer 7

1. Temperature
2. pH
3. Enzyme concentration
4. Substrate concentration

Question 8

Explain how pH affects enzyme activty and thus the rate of an enzyme controlled reaction

Answer 8

1. An enzyme’s tertiary structure is held together by hydrogen bonds, ionic bonds and hydrophyllic/hydrophobic interactions
2. As the pH of the enzymes moves away from optimum temperature, this changes the concentration of H⁺ions which disrupts the hydrogen bonds,ionic bonds and hydrophyllic/hydrophobic interactions
3. This changes the tertiary structure of the enzyme, which changes the shape of the enzyme molecule and its active site
4. This means that no more enzyme-substrate complexes can be formed which means that the rate of reaction decreases and becomes zero

Question 9

Explain how substrate concentration affects enzyme activity and thus the rate of an enzyme controlled reaction

Answer 9

1. As the concentration of the substrate molecule increases the number of substrate molecules per unit volume increases
2. This increase in the concnetration of substrate molecules increases the frequency of successful collisions between the substrate molecules and the enzyme active site which more that there is an increase in the number of enzyme-substrate complexes forming and so the rate of reaction increases
3. At v-max, all of the enzyme active sites are occupied by substrate molecules which means that no more enzyme-substrate complexes can be formed and the rate of reaction levels off .
4. Enzyme concentrations is now the limiting factor

Question 10

Explain how enzyme concentration affects enzyme activity and thus the rate of an enzyme controlled reaction

Answer 10

1. As the concentration of enzyme molecules increases, the number of available active sites per unit volume increases
2. This increases the rate of reaction as it means that there is an increase frequency of successful collisions between the enzyme active site and the substrate molecules which means that there is an increase in the enzyme-substrate complexes formed
3. At v-max all of the active sites are occupied by substrate molecules, this means that as the enzyme concentration increases no more enzyme-substrate complexes can be formed and the rate of reaction levels off
4. Now, substrate concentration is the limiting factor

Question 11

Draw a graph to show the effect of substrate/enzyme concentration on the rate of an enzyme controlled reaction

Answer 11

A graph which increases at first and then reaches a maximum then levels off/plateaus

Question 12

Draw the graph showing the effect of pH on enzyme activity

Answer 12

A graph which increases rapidly, has a peak, then decreases just as rapidly