Enzymes Factors Affecting Activity

Question 1

Name 4 factors that affect enzyme activity.

Answer 1

Temperature, pH, substrate concentration, enzyme concentration

These factors influence the rate at which enzymes catalyze reactions.

Question 2

How does temperature affect enzyme activity?

Answer 2

Increasing temperature raises reaction rate to an optimum point, after which the rate decreases

Beyond the optimum temperature, enzymes may denature, due to ionic and hydrogen bonds breaking. This changes the shape of the enzymes active site, leading to reduced activity.

Question 3

Fill in the blank: Increasing temperature increases the rate of reaction to a particular point called the _______.

Answer 3

optimum temperature

This is the temperature at which enzyme activity is maximized.

Question 4

How does temperature affect enzyme activity?

Answer 4

Increasing temperature increases the rate of reaction to a particular point (the optimum temperature), and then further increase in temperature causes a decrease in the rate of reaction.

Question 5

What is the optimum temperature in relation to enzyme activity?

Answer 5

The optimum temperature is the temperature at which the rate of reaction is maximized.

Question 6

True or False: Enzyme activity continues to increase indefinitely with rising temperature.

Answer 6

False

Question 7

Fill in the blank: Increasing temperature increases the rate of reaction to a particular point known as the _______.

Answer 7

[optimum temperature]

Question 8

What happens to enzyme activity after reaching the optimum temperature?

Answer 8

Further increase in temperature causes a decrease in the rate of reaction.

Question 9

Explain how temperature affects enzyme activity

Answer 9

•Increasing temperature increases kinetic energy of the substrate and enzyme
•They collide more, causing more frequent formation of enzyme-substrate complexes
•At higher temperatures the increased temperature causes hydrogen bonds of the tertiary structure to break and the shape of the active site changes, then enzyme is denatured
•The substrate is no longer complementary and doesn’t fit into the active site. Hence the rate of enzyme activity decreases.
•At very high temperatures all enzymes are denatured hence enzyme activity stops

Question 10

What is the optimum temperature?

Answer 10

The temperature at which the enzyme has the greatest activity (highest rate of reaction).

Question 11

Which enzyme bonds are broken most at high temperatures?

Answer 11

Hydrogen bonds in the tertiary structure break, altering the shape of the active site.

Question 12

Which enzyme bonds break most at non-optimal pH?

Answer 12

Ionic bonds in the tertiary structure break, altering the shape of the active site.

Question 13

How is an enzyme denatured?

Answer 13

The hydrogen or ionic bonds in the tertiary structure of an enzyme break, permanently changing the shape of the active site.

Question 14

What happens to the active site of an enzyme when it is denatured?

Answer 14

The shape of the active site is permanently changed and is no longer complementary to the substrate.

Question 15

What is the result of an enzyme being denatured?

Answer 15

It can no longer catalyse the reaction as the enzyme-substrate complex cannot be formed.

Question 16

How does pH affect enzyme activity?

Answer 16

The further away from non-optimal pH, the greater the reduction in enzyme activity.

Question 17

What happens to ionic bonds in an enzyme at non-optimal pH values?

Answer 17

Ionic bonds in the tertiary structure are disrupted, changing the shape of the active site.

Question 18

What effect does changing pH have on enzyme-substrate complexes?

Answer 18

Fewer enzyme-substrate complexes are formed at non-optimal pH values.

Question 19

What is the relationship between substrate concentration and enzyme activity?

Answer 19

Increasing substrate concentration increases the rate of reaction to a particular point.

Question 20

What happens when substrate concentration increases beyond a certain point?

Answer 20

Further increase in substrate concentration has no further effect on the rate of reaction.

Question 21

Why does increasing substrate concentration initially increase enzyme activity?

Answer 21

It provides more substrate molecules to fit into the active sites, allowing more enzyme-substrate complexes to form.

Question 22

What becomes limiting at higher substrate concentrations?

Answer 22

The number of active sites becomes limiting as enzyme-substrate complexes form at the maximal rate.

Question 23

Sketch the graph for how temperature affects enzyme activity

Answer 23

Question 24

Sketch the graph for pH affecting enzyme activity

Answer 24

Question 25

Sketch the graph for substrate concentration of enzyme activity

Answer 25

Question 26

Sketch the graph for enzyme concentration of enzyme activity

Answer 26

Question 27

Draw a graph for substrate concentrations affect on distinguishing between competitive and non-competitive inhibitors

Answer 27

Question 28

How does enzyme concentration affect enzyme activity?

Answer 28

As enzyme concentration increases, the rate of reaction increases to a maximum, after which further increases have no effect on the rate. ## Footnote In living cells, the maximum rate of reaction is often reached due to limiting substrate availability.

Question 29

What happens to the rate of reaction at higher enzyme concentrations?

Answer 29

The number of substrate molecules becomes limiting, and no further increase in the rate of reaction is observed. ## Footnote Enzyme-substrate complexes form at the maximum rate.

Question 30

What is an allosteric enzyme?

Answer 30

An enzyme with a second site where non-substrate molecules can attach.

Question 31

What is an enzyme inhibitor?

Answer 31

Substances that reduce enzyme activity either directly or indirectly affecting the functioning of the active site.

Question 32

Is inhibition a temporary effect?

Answer 32

Many inhibitors are reversible, but some are irreversible, causing permanent damage to the enzyme.

Question 33

What is competitive inhibition?

Answer 33

An inhibitor that competes with the usual substrate for the active site.

Question 34

What is non-competitive inhibition?

Answer 34

An inhibitor that attaches itself to a part of the enzyme other than the active site.

Question 35

How can changing substrate concentration help distinguish between competitive and non-competitive inhibition?

Answer 35

Increasing substrate concentration can overcome the effect of a competitive inhibitor but will not reduce the effect of a non-competitive inhibitor.

Question 36

Fill in the blank: Increasing enzyme concentration provides more _______ and more enzyme-substrate complexes can form.

Answer 36

active sites

Question 37

True or False: In most living systems, substrate is seldom limiting.

Answer 37

True