U1T6 – Factors Affecting Enzymes

Factors Affecting Enzymes

1 / 25

Which letter on the above graph shows when the enzyme is denatured?

A

C

A & C

2 / 25

Which letter on the above graph shows when the most enzyme-substrate complexes will be formed?

A

B

C

3 / 25

What has happened to the enzyme when it becomes denatured with a high temperature?

It has broken down all the substrate, so the reaction stops.

The substrate has changed shape, and is no longer complementary to the active site.

The tertiary structure of the active site has changed shape, and is no longer complementary to the substrate.

4 / 25

When an enzyme is denatured, which bonds are NOT broken?

Peptide Bonds

Hydrogen Bonds

Di-Sulphide Bonds

5 / 25

On the above graph, lines A and B represent the same enzyme, in identical conditions; the only difference is the temperature.

What would happen to the red line after this point ?

It would eventually plateau below the black line

It would eventually plateau on the black line.

It would not plateau, but continue straight.

6 / 25

The optimum temperature for this enzyme is actually 40^oC. Describe what the line would look like on the above graph.

It would rise at the same rate as 25oC, but the extend beyond, and plateau above it.

It would rise steeper than 25oC at the start , but then plateau above it.

It would rise steeper than 25oC at the start , but then plateau at the same mass.

7 / 25

Which points on the above graph show when the enzyme is denatured?

pH4.5

pH 10.5

pH4.5 & pH10.5

8 / 25

Which bonds are disrupted by changes in pH?

Hydrogen and Ionic Bonds

Hydrogen and Di-sulphide Bonds

Hydrogen, Ionic and Di-sulphide Bonds

9 / 25

Which letter on the above graph is the ' Saturation' point?

A

B

C

10 / 25

Why does the graph plateau?

Because the enzyme has denatured so stops catalysing.

Because all the available active sites are occupied.

Because all the available substrate has been used up.

11 / 25

If everything else was kept the same, what effect would adding more enzyme have on the position of the line?

It will be steeper at the start, and plateau above the current line.

It will be steeper at the start, but plateau at the same rate.

No Effect.

12 / 25

Which line shows the rate when substrate is limited ?

A

B

13 / 25

Explain why line B forms a plateau:

Because the enzyme has denatured.

Because the enzyme is catalysing as fast as it can, and cannot make any more enzyme-substrate complexes.

Because eventually all the substrate is used up, and no new product can be formed, no matter how much enzyme is added.

14 / 25

Will line A ever plateau if the substrate is unlimited?

Yes

No

15 / 25

Where do competitive inhibitors bind ?

The Active Site

Somewhere on the protein other than the active site.

16 / 25

Describe what the line would look like when a competitive inhibitor was added to the reaction.

The line would increase less steeply, but it would eventually plateau at the same rate as withut an inhibitor.

The line would be less steep at the start, and would plateau at a rate below the line without an inhibitor.

The line would go up at the same gradient at the start, but would then plateau at a lower rate.

17 / 25

How do competitive inhibitors bring about a decrease in rate?

By changing the shape of the active site.

By changing the charge on the active site.

By binding to, therefore blocking the active site.

18 / 25

How do you reduce the effect of a competitive inhibitor?

Decrease the amount of substrate.

Increase the amount of substrate.

Reduce the pH.

19 / 25

Where do non-competitive inhibitors bind?

The Active Site.

Somewhere on the protein other than the active site.

20 / 25

Describe what the line would look like when a non-competitive inhibitor was added to the reaction.

The line would increase less steeply, but it would eventually plateau at the same rate as withut an inhibitor.

The line would be less steep at the start, and would plateau at a rate below the line without an inhibitor.

The line would go up at the same gradient at the start, but would then plateau at a lower rate.

21 / 25

Explain how non-competitive inhibitors reduce rate.

The binding elsewhere, causes a change in the primary structure, so alters the shape of the active site.

The binding to the active site prevents enzyme-substrate complexes from forming.

The binding elsewhere, causes a change in the tertiary structure, so alters the shape of the active site.

22 / 25

Will increasing the concentration of substrate cause an increase in the rate of an enzyme inhibited by a non-competitive inhibitor?

Yes

No

23 / 25

Methanol is toxic. It binds to the enzyme alcohol dehydrogenase . Ethanol is similar in structure to methanol. One treatment for Methanol poisoning is to drink a lot of ethanol. What type of inhibitor is methanol?

Competitive

Non-competitive

24 / 25

Penicillin works by binding to an enzyme called transpeptidase in bacteria, changing the shape of the active site. When penicillin binds, it means the bacteria can no longer make cross-bridges in the bacterial cell wall. What type of inhibitor is penicillin?

Competitive

Non-competitive

25 / 25

Viagra is a similar shape to cyclic GMP ( cGMP). Both will block an enzyme called PDE5. cGMP causes vasodilation. What sort of inhibitor is Viagra?

Competitive

Non-competitive

Thank you for taking the quiz. Please fill in the fields below and you will receive your results in an email.

If you have been set this as homework, you should forward this email to your teacher as evidence you have completed the quiz.

If you don't receive your email please check your spam or junk folder.

Your score is

0%

Recent Posts

Categories