Enzymes - B3

Question 1

True or false: enzymes are required for metabolic processes to take place.

Answer 1

True.

Question 2

What do enzymes speed up reactions to be fast enough for?

Answer 2

Enzymes speed up reactions to be fast enough for life to continue.

Question 3

What are the main two different types of proteins?

Answer 3

Fibrous and globular

Question 4

What are the characteristics of a fibrous protein?

Answer 4

-Typically long and thin
-Insoluble
-Often have structural functions

Question 5

What are the characteristics of a globular protein?

Answer 5

-More spherical in shape
-Soluble
-Often have biochemical functions e.g.
enzymes

Question 6

Do enzymes lower the activation energy?

Answer 6

Yes, and this is what allows reactions to happen faster

Question 7

What causes various parts of an enzyme molecule to move?

Answer 7

It moves in response to a change in it’s environment. Some are small, some are big.

Question 8

What is the induced-fit model?

Answer 8

1) Active site is not complimentary to the substrate
2)substrate binds to the active site - active site becomes complementary in response
3)they form an enzyme substrate complex -> substrate and active site have binded together
4)active site puts pressure/tension/stress on bond
5)by doing this, it reduces activation energy

Question 9

What is pH?

Answer 9

the pH of a solution is a measure of it’s hydrogen ion conc.

Question 10

How does pH change effect the rate of reaction?

Answer 10

-As you change the pH, the charges of the R group are changed
-ionic bonds start to break
-the tertiary structure changes
-active site will no longer become complementary to the substrate
-NO enzyme-substrate complex

Question 11

How does temperature effect the rate of reaction?

Answer 11

-as temp. increases, there’s more kinetic energy, and more successful collisions, so more enzyme-substrate complexes formed
-at the optimum temp., the most E-S complexes are formed, kinetic energy increases, and there are more successful collisions
-If kinetic energy gets to high, hydrogen ionic bonds break, which changes the tertiary structure
-active site no longer complimentary to substrate

Question 12

What is the effect of substrate concentration on the rate of reaction?

Answer 12

-Before point of saturation - substrate conc. is limiting factor(A)
-After point of saturation - enzymes are the limiting factor(B)
A- low r.o.r at low substrate conc.s as not all active sites of enzymes are saturated(filled)
B- no rise in r.o.r as enzymes cannot form anymore E-S complexes as all active sites are filled -> no. of enzymes is limiting factor

Question 13

What does an inhibitor do?

Answer 13

reduce the rate of an enzyme catalysed reaction by interfering with the enzyme in some way.

Question 14

What are the two types of inhibitor, and are they permanent or temporary?

Answer 14

competitive - temporary
non-competitive - permanent

Question 15

What is the action of a competitive enzyme inhibitor?

Answer 15

Similar shape to substrate > will bind to active site > prevents enzyme from forming enzyme-substrate complexes > rate of reaction decreases > temporary effect

Question 16

What is the action of a non-competitive enzyme inhibitor?

Answer 16

Attaches to allosteric site > changes tertiary structure > change the active site so it’s no longer complimentary( no E-S complexes) >permenant