Enzymes 1

Question 1

What is an enzyme?

Answer 1

Globular protein, no defined structure and biological catalyst.

Question 2

Define a ribozyme.

Answer 2

Catalytic RNA molecules with no protein compounds.

Question 3

Give one function of RNA.

Answer 3

Can form secondary structures like amino acids forming different shapes.

Question 4

Define cofactors.

Answer 4

Non-protein components which are necessary for cell function.

Question 5

Define coenzymes.

Answer 5

Complex organic molecules which are usually produced from a vitamin.

Question 6

Define prosthetic group.

Answer 6

Cofactor which is covalently bonded and necessary for function of an enzyme.

Question 7

Define an apoenzyme.

Answer 7

Protein component of an enzyme containing a cofactor.

Question 8

Define a holoenzyme.

Answer 8

Whole enzyme (cofactor and apoenzyme).

Question 9

Define substrate.

Answer 9

Molecule acted on by the enzyme.

Question 10

Define an active site.

Answer 10

Part of the enzyme in which the substrate binds to.

Question 11

Name 2 things enzymes can’t do.

Answer 11

Move equilibrium.

Make a nonspontaneous reaction spontaneous.

Question 12

Name 3 things an enzyme can do.

Answer 12

Increase rates of spontaneous reactions
Lower activation energy
Accelerate movement towards equilibrium

Question 13

Define an energy barrier.

Answer 13

The energy required for a reaction to occur.

Question 14

The active site is ______ to the substrate.

Answer 14

Complementary.

Question 15

If the active site and the substrate are exactly complementary, then the enzyme substrate complex is ______ stable.

Answer 15

More

Question 16

What is the active site actually complementary to?

Answer 16

The transition state (catalysis).

Question 17

Describe entropy reduction.

Answer 17

Molecules react by bumping into each other and enzymes help this happen more frequently to reduce activation energy.

Question 18

Describe desolvation.

Answer 18

Weak bonds between the substrate and enzyme replace most or all of the hydrogen bonds between the substrate and aqueous solution to make the breaking of bonds easier.

Question 19

Describe induced fit.

Answer 19

Conformational changes occur in the enzyme structure when a substrate binds.

Question 20

What are the 3 ways to analyse an enzyme?

Answer 20

Enzyme kinetics
Mutagenesis
3D structure

Question 21

Describe the process of measuring enzyme kinetics.

Answer 21

Change of substrate concentration changes the initial rate of reaction.
As reaction proceeds, substrate is used up and rate of reaction changes.
Initial velocity (Vo) can be measured if initial substrate concentration doesn't change.
Vmax occurs because all of the enzyme active sites are saturated with substrates.

Question 22

What is the M-M equation?

Answer 22

Vo = Vmax [S]

Km + [S]

Question 23

What is the M-M equation with a low substrate concentration?

Answer 23

Vo = Vmax [S]

Km

Question 24

What is the M-M equation with a high substrate concentration?

Answer 24

Vo = Vmax

Question 25

What is the M-M equation when substrate concentration equals Km?

Answer 25

Vo = Vmax

2

Question 26

Why is Vmax always a prediction?

Answer 26

Vmax is never fully reached.

Question 27

How can you get a Lineweaver-Burk plot?

Answer 27

Using the inverse data from an M-M equation.