Enzymes 2

Question 1

Explain why high temperature affects enzyme function.

Answer 1

High temperatures have more kinetic energy; Breaks hydrogen/ionic bonds in the 3-D tertiary structure; changing the shape of the active site, it’s no longer complimentary to the substrate so fewer enzyme-substrate complexes are formed;

Question 2

Suggest an advantage of a bacterium secreting extracellular proteases.

Answer 2

To digest/hydrolyse proteins into amino acids; amino acids can then be absorbed for making proteins for growth/reproduction;

Question 3

Suggest why some enzyme-catalysed reactions will only occur if the substrate has been phosphorylated.

Answer 3

Phosphorylation makes the substrate more reactive/lowers the activation energy for the reaction.

Question 4

Explain why low temperature affects enzyme function.

Answer 4

Temperatures lower than the optimum means enzyme and substrate have less kinetic energy; therefore the enzyme and substrate will collide less often with the sufficient energy for the reaction to take place, fewer enzyme substrate complexes. Lower rate of reaction.

Question 5

What are the control variables for enzyme-substrate investigations. (use the context of the question)

Answer 5

Concentration of enzyme; concentration of substrate; volume of enzyme; volume of substrate; temperature; pH; concentration/volume inhibitor;

Question 6

What is a suitable control investigation for enzyme-substrate investigations.

Answer 6

All the same conditions, but use a boiled (denatured) enzyme solution.

Question 7

Describe and explain the shape of a normal substrate concentration vs rate of reaction graph for an enzyme controlled reaction.

Answer 7

There is an initial increase because more enzyme-substrate complexes are formed; Then it will level off as there will be no free enzyme active sites, as the enzyme is the limiting factor.

Question 8

8. Explain why a mutation in the code for an enzyme may affect it’s function.

Answer 8

The mutation may code for a different amino acid at the active site of the enzyme; this will lead to a structural difference due to a change in the ionic/hydrogen bonds or disulphide bridge between the R-groups of the amino acids; the active site is no longer complimentary to the substrate; so fewer enzyme-substrate complexes will form.

Question 9

Explain why a mutation in the code for an enzyme may not affect it’s function.

Answer 9

The mutation may be for a substitution that codes for the same amino acid (the code is degenerate), this will therefore not change the structure of the enzyme’s active site. The