Exam 1: Chapter 6 - Enzymes

Question 1

What does the enzyme do to the transition state and activation energy

Answer 1

stabilize the transition state and lower the activation energy

Question 2

catalyst (enzyme)

Answer 2

increases the rate of a reaction

Question 3

what is the reactant called in an enzyme‑catalyzed reaction

Answer 3

substrate

Question 4

are enzymes highly specific?

Answer 4

Enzymes are generally highly specific for a specific substrate. Nonbiological catalysts typically facilitate many types of reactions and are therefore called nonspecific catalysts.

Question 5

where does catalysis occur?

Answer 5

active site

Question 6

what does an apoenzyme require to be a holoenzyme?

Answer 6

a cofactor

Question 7

cofactor

Answer 7

a small organic molecule (a coenzyme) or a metal ion that converts catalytically inactive apoenzyme into an active holoenzyme

Question 8

coenzyme

Answer 8

If the cofactor is an organic molecule, such as a vitamin, it is referred to as a coenzyme.

Question 9

can enzymes change the position of equlibrium?

Answer 9

no, but they can assist in reaching equilibrium by lowering activation energy

Question 10

If the product of a reaction has less free energy than the substrate of the reaction, overall free energy decreases, what happens to ΔG and is it exergonic or endergonic?

Answer 10

the change in free energy, ΔG, will be negative, This is called an exergonic reaction (negative ΔG), and it happen spontaneously

Question 11

If the product of a reaction has more free energy than the substrate of the reaction, overall free energy increases, what happens to ΔG and is it exergonic or endergonic?

Answer 11

or such a reaction, the change in free energy, ΔG, will be positive, which indicates the reaction is endergonic and not spontaneous because the reaction required an input of free energy to occur.

Question 12

What interactions allow the substrate to bind to the enzyme

Answer 12

through noncovalent reactions such as hydrogen bonds and van de waals interactions

Question 13

lock and key model

Answer 13

the enzyme active site has a rigid structure complementary to a specific substrate

Question 14

induced fit model

Answer 14

the enzyme conformation changes when it binds the substrate so that the active site fits the substrate

Question 15

metalloenzyme

Answer 15

tightly bound metal ions (usually transition metals) that usually mediate redox reactions through reversible changes in metal ion oxidation states

Question 16

metal-activated enzyme

Answer 16

Use several metal ions of similar size and charge that are loosely bound to the enzyme and can electrostatically stabilize or shield negative charges