3.1.4.2 Many Proteins are emzymes

Question 1

What are enzymes?

Answer 1

Enzymes are tertiary structure proteins, so that unique 3D shape and function is that they lower the activation energy of the reactions they catalyse.

Question 2

What is special about the active site?

Answer 2

It’s specific and unique in shape due to the folding and bonding in the tertiary structure of the protein
And because of this specific active site, enzymes can only attach to substrates that are complementary in shape.

Question 3

What is the induced fit model?

Answer 3

When the enzyme’s active site slightly changes shape to mould around the substrate

When the E-S complex forms it puts strain on the bond and therefore lowers the activation energy

Question 4

Factors affecting the rate of enzyme controlled reactions (5)

Answer 4

Temperature
pH
Substrate concentrations
Enzyme concentration
Inhibitors

Question 5

What happens to the enzyme if there is too little or too much temperature?

Answer 5

If temp is too low, not enough kinetic energy for successful collisions between the enzyme and substrate.

If temp is too high the enzyme denatures, active site changes shape and E-S complexes cannot form.

Question 6

What happens to the enzyme if there is too little or too much of a pH?

Answer 6

Too low or too high a pH will interfere with the charges in the amino acids in the active site. This can break the bonds e.g. the ionic bonds holding the tertiary structure in place and therefore the active site changes shape. Therefore, enzyme denatures and fewer E-S complexes form

Question 7

What happens to the enzyme if there’s a lack of or an abundance of a substrate and enzyme concentration?

Answer 7

If there is insufficient substrate, then the reaction will be slower as there will be fewer collisions between the enzyme and substrate.

If there is insufficient enzymes then the enzyme active sores will become saturated with substrate and unable to work any faster.

Question 8

What happens to the enzyme when there is a competitive inhibitor?

Answer 8

Competitive inhibitor has same shape as substrate and binds to active site preventing E-S complex.

If you add more substrate it will out compete the inhibitor, knocking them out of the active site.

Question 9

What happens to the enzyme when there is a non-competitive inhibitor?

Answer 9

It binds to the allosteric site (someplace else that isn’t the active site but still on the enzyme)
Causes the active site to change shape and therefore no E-S complex
The substrate can no longer bind