2.2 Mechanisms of Enzyme activity; 2.4 Local Conditions

Question 1

how to enzymes exert their effect?

Answer 1

they stabilize the transition state and lower the activation energy

Question 2

lock and key theory of enzymes

Answer 2

The enzyme and substrate are exactly complementary and fit together like a key into a lock

Question 3

induced fit enzyme theory

Answer 3

The enzyme and substrate undergo conformational changes to interact fully

Question 4

endergonic reactions

Answer 4

requires energy input

non spontaneous (positive delta G)

Question 5

exergonic reactions

Answer 5

release energy

spontaneous (negative delta G)

Question 6

do enzymes change the overall energy change of a reaction?

Answer 6

NO! delta G does not change with enzyme presence

Question 7

can enzymes affect the reaction equilibrium?

Answer 7

NO! the enzymes only affect the rate at which equilibrium is reached

Question 8

Typical features of cofactors and coenzymes:

Answer 8

small

ions

concnetrated in an area?

charged?

Question 9

Apoenzymes vs holoenzymes

Answer 9

apoenzymes: no cofactors or coenzymes
holoenzymes: cofactors or coenzymes

Question 10

Prosthetic groups

Answer 10

permanently attached cofactors/coenzymes? commonly metal ions

Question 11

lock and key theory vs induced fit model

Answer 11

lock and key: enzyme has active site that perfectly matches substrate

induced fit: binding of substrate causes conformation change of enzyme to then have perfect fit with substrate (ES complex is a better fit than enzyme alone)

Question 12

cofactors

Answer 12

a non-protein compound or metal ion that is required by some enzymes

All coenzymes are cofactors, but not all cofactors are coenzymes

Question 13

coenzyme

Answer 13

an organic cofactor (contains carbon)

All coenzymes are cofactors, but not all cofactors are coenzymes

Question 14

what environment factors can affect enzyme activity?

Answer 14

temperature, pH, and salinity (saltiness)