Overview of Metabolism

Question 1

What is catabolism?

Answer 1

Breaking down fuel molecules to generate energy

Question 2

What is anabolism?

Answer 2

Using energy to build complex biomolecules require for life

Question 3

Can Gibbs free energy be directly measured?

Answer 3

No, only the change in free energy in a reaction

Question 4

Is an exergonic reaction energetically favourable?

Answer 4

Yes

Question 5

Is an endergonic reaction energetically favourable?

Answer 5

No

Question 6

What is the formula for the equilibrium constant, K_eq?

Answer 6

[C][D]/[A][B]

Question 7

When K_eq > 1 does the reaction favour reactant or products?

Answer 7

Products

Question 8

When K_eq<1 does the reaction favour reactants or products?

Answer 8

Reactants

Question 9

What term is used when the equilibrium constant is determined at pH7?

Answer 9

K_eq’

Question 10

How is ΔG worked out for a reaction which is not at equilibrium?

Answer 10

ΔG=ΔGº + RT x (ln[C][D]/[A][B])

Question 11

What is a metabolic pathway?

Answer 11

A series of enzyme-catalysed reactions in which:

• Each reaction is specific
• Overall the set of reactions is energetically favourable

Question 12

What is substrate level phosphorylation?

Answer 12

Chemicals with high phosphoryl-transfer potential can pass their phosphate group directly to ADP, making ATP

Question 13

What percentage of ATP produced by oxidation of glucose comes from oxidative phosphorylation?

Answer 13

≈90%

Question 14

What are activated carriers?

Answer 14

Biomolecules that store energy in the form of transferable chemical groups

Question 15

NADH and NADPH are activated carriers of what?

Answer 15

Electrons

Question 16

How many electrons can NAD+ accept?

Answer 16

2

Question 17

What kind of reactions is NADPH usually used in?

Answer 17

NADPH

Question 18

What kind of reaction is NADH usually used in?

Answer 18

Catabolic

Question 19

Why is NADH a good store of potential energy as reducing power?

Answer 19

Loss of electrons is very energetically favourable

Question 20

What is NADH an important coenzyme for?

Answer 20

Many dehydrogenases

Question 21

What is FADH₂ an activated carrier of?

Answer 21

Electrons

Question 22

How does FAD form FADH₂?

Answer 22

It is reduced by 2 electrons and 2 protons

Question 23

How does FAD act as a coenzyme?

Answer 23

It is covalently attached to the enzymes for which is acts as a coenzyme

Question 24

What is coenzyme A a carrier of?

Answer 24

Acyl groups

Question 25

How is metabolism controlled in the short term?

Answer 25

• binding of allosteric inhibitors/activators to alter enzyme activity
• Covalent modification e.g. phosphorylation alters enzyme activity

Question 26

How is metabolism controlled in the long term?

Answer 26

• changes in gene expression to alter total amount of an enzyme
• changes in proteolysis to alter total amount of an enzyme