Lecture 7

Question 1

What is ΔG?

Answer 1

Gibbs energy, measure of spontaneity

Question 2

When ΔG < 0

Answer 2

The reaction is spontaneous, energy released

Question 3

When ΔG > 0

Answer 3

The reaction is non-spontaneous, energy required

Question 4

When ΔG = 0

Answer 4

The reaction is at equilibrium, no work can be done

Question 5

How do enzymes catalyse thermodynamically favourable reactions?

Answer 5

By providing an alternate pathway of lower energy

Question 6

What is required for a reaction to reach a high-energy transition state?

Answer 6

Activation energy supplied

Question 7

What is the activation energy, as read off a reaction progress graph?

Answer 7

The difference in energy between the reactants and the activated complex/transition state

Question 8

How do enzymes influence forward and reverse reactions?

Answer 8

By decreasing activation energy, the forward and reverse reactions are accelerated equally

Question 9

What is the symbol for activation energy?

Answer 9

Ea OR ΔG‡

Question 10

How does ΔG change when an enzyme is introduced to a reaction?

Answer 10

There is no change, only ΔG‡ decreases

Question 11

What type of molecule makes up the majority of enzymes?

Answer 11

Proteins

Question 12

What are the main classes of enzymes?

Answer 12

Oxidoreductase, Transferase, Hydrolase, Lyase, Isomerase, Ligase

Question 13

What are oxidoreductase enzymes?

Answer 13

RedOx enzymes, transfer electrons

Question 14

What are transferase enzymes?

Answer 14

Transfer enzymes, of functional groups

Question 15

What are hydrolase enzymes?

Answer 15

Hydrolysis enzymes, using H2O

Question 16

What are lyase enzymes?

Answer 16

Non-hydrolytic enzymes, for breaking or making bonds not involving water

Question 17

What are isomerase enzymes?

Answer 17

Transfer of atom or group enzymes, within a molecule to yield an isomeric form

Question 18

What are ligase enzymes?

Answer 18

Joining of two molecules together (Forming a new bond, usually coupled to ATP

Question 19

What are cofactors?

Answer 19

Non-protein factors that help catalyse reactions

Question 20

What are the classes of cofactors?

Answer 20

Metal ions and co-enzymes

Question 21

Describe metal ions

Answer 21

Lewis acids that form coordination compounds with precise geometries

Question 22

What are examples of metal ions?

Answer 22

Mg2+, Zn2+, Fe2+, Fe3+

Question 23

What are the enzymes related to Mg2+?

Answer 23

DNA polymerase, hexokinase, Pyruvate kinase

Question 24

What are the enzymes related to Zn2+?

Answer 24

Alcohol dehydrogenase, carbonic anhydrase

Question 25

What are the enzymes related to Fe2+ and Fe3+ ?

Answer 25

Cytochrome oxidase, peroxidase

Question 26

What are coenzymes?

Answer 26

Small organic molecules; co-substrates; carriers of electrons, atoms or functional groups; often derived from vitamins

Question 27

what is vitamin B6?

Answer 27

Pyridoxine

Question 28

What coenzyme is related to vitamin B6?

Answer 28

Pyridoxal phosphate (PLP)