Core component 4 - Factors Effecting Enzyme Action

Question 1

Describe the graph of temperature against rate of reaction

Answer 1

The rate of reaction increases as temperature increases, steadily from 0 degrees Celsius up to 40 degrees Celsius where it reaches its optimum and after 40 Celsius the rate of reaction drops rapidly up to 55 Celsius.

Question 2

Why does the rate of reaction increase as temperature increases?

Answer 2

As temperature increases, kinetic energy increases, this causes the enzyme and the substrate to move faster and therefore there are more collisions and more enzyme substrate complexes formed.

Question 3

Why does the rate of reaction decrease after 40 degrees Celsius?

Answer 3

When temperature gets above 40 degrees this causes the enzyme to denature and it breaks the hydrogen bonds which hold the 3-D shape together meaning the substrate can no long fit in the active site

Question 4

Explain why the rate of reaction is low at very low temperatures?

Answer 4

The enzyme is inactivated due to it having a very low kinetic energy

Question 5

In terms of levels of structure what changes when an enzyme denatures?

Answer 5

It’s primary structure, the order of amino acids stays the same however it’s secondary structure and tertiary structure are effected.

Question 6

Describe the ph against rate of reaction graph

Answer 6

From 3-7 as PH increases so does the rate of reaction, 7 being the optimum PH and then from 7–11 PH as it increases the rate of reaction decreases

Question 7

Explain the PH against rate of reaction graph

Answer 7

Most enzymes have an optimum temperature where the rate of the reaction is highest and small changes around the optimum cause reversible changes but extremes of PH cause the enzyme to denature due to the disruption to the hydrogen bonds and 3-D structure (active site) and therefore no enzyme substrate complexes can be formed.

Question 8

What happens to enzymes at low PH?

Answer 8

Excess H+ ions are attracted to negative charges and neutralise them which effects bonds in enzyme.

Question 9

What happens to enzymes at a high PH?

Answer 9

Excess OH- ions neutralise the positive charges which causes changes in bonds and therefore structure.

Question 10

Describe the substrate concentration against rate of reaction graph

Answer 10

As substrate concentration increases rate of reaction increases and they are directionally proportional however towards the end the line begins to plateau

Question 11

Explain the substrate concentration against rate of reaction graph

Answer 11

As the amount of substrate increases, more active sites can be filled and therefore more enzyme substrate complexes can be formed. However, as even more substrate is added the rate cannot increase anymore as all active sights are saturated meaning that another factor like temperature is the limiting factor

Question 12

Describe the relationship between enzyme concentration and rate of reaction

Answer 12

If temperature and PH are optimal and there is an excess of substrate the rate of reaction is directly proportional to the enzyme concentration

Question 13

What is the importance of a buffer?

Answer 13

They maintain a constant pH.