Metabolism - Lecture Twenty-Seven

Question 1

Fuel molecules

Answer 1

Nutrients such as glucose, fats and protein

Question 2

Why do we have fuel molecule intake?

Answer 2

To do our cellular work through ATP energy

Question 3

What does the ∆G of a reaction tell us?

Answer 3

The relative abundance of the substrates and products and the energy stored in the chemical bonds of the products and substrates

Question 4

∆G < 0 for A ➝ B

Answer 4

The reaction is spontaneous, energy is released and is energetically favourable

Question 5

∆G = 0 for A ➝ B

Answer 5

The reaction is at equilibrium, and there is no change in energy

Question 6

∆G > 0 for A ➝ B

Answer 6

The reaction is not spontaneous, energy is required and is energetically unfavourable

Question 7

∆G

Answer 7

Specific conditions

Question 8

∆G˚

Answer 8

Standard conditions - all reactants 1M

Question 9

∆G˚’

Answer 9

At pH 7

Question 10

When is ATP hydrolysis energetically favourable?

Answer 10

At ∆G˚’ = -30kJ/mol

Question 11

When is ATP synthesis energetically unfavourable?

Answer 11

ΔG˚’ = 30 kJ/mol

Question 12

Why do enzymes often couple reactions?

Answer 12

To drive necessary unfavourable reactions?

Question 13

Two key types of reactions

Answer 13

Phosphorylation of ADP to ATP and redox reactions

Question 14

Coenzymes NAD and FAD

Answer 14

Interact with various enzymes to accept and donate reducing equivalents (hydrogen)

Question 15

What do biological redox reactions often involve?

Answer 15

The transfer of hydrogen atoms (includes an electron)

Question 16

Reducing equivalent

Answer 16

Hydrogen

Question 17

What enzymes catalyse redox reactions?

Answer 17

Dehydrogenases

Question 18

What are coenzymes?

Answer 18

Coenzymes are small organic molecules that are often derived from vitamins. Coenzymes have a low concentration in cells and act as carriers. They can exist in two forms.

Question 19

NAD: Nicotinamide adenine dinucleotide

Answer 19

Is derived from Niacin (vitamin B3) which accepts hydrogens and electrons in metabolic pathways (glycolysis, fatty acid oxidation, citric acid cycle). NAD undergoes a two electron reduction where it accepts two hydrogen.

Question 20

FAD: Flavin adenine dinucleotide

Answer 20

Is derived from riboflavin (vitamin B2) which accepts hydrogens in pathways (fatty acid oxidation, citric acid cycle) FAD undergoes a two electron reduction where it accepts two hydrogen.

Question 21

Flavin coenzymes

Answer 21

Are tightly bound to the proteins with which they interact (flavoproteins)

Question 22

Coenzyme A (CoA)

Answer 22

Is derived from pantothenic acid (vitamin B5) and is not a carrier of electrons (not reduced or oxidised)

Question 23

Carriers of CoA

Answer 23

Acyl groups

CH3(CH2)nCH3COO-

Question 24

Two forms of CoA

Answer 24

Free coenzyme A - CoASH and Acyl group attached - AcCoA