Making ATP 1: Substrate-Level Phosphorylation and ETC

Question 1

Definition of substrate-level phosphorylation

Answer 1

ATP derived from glycolysis or the creatine system

Question 2

Energy required to form ATP

Answer 2

dG ~30kJ/mol

Question 3

What reactions ATP can power

Answer 3

Reactions with dG <30kJ/mol

Question 4

Amount of ATP derived per creatine molecule

Answer 4

1 ATP?

Question 5

Energy derived from breaking creatine-phosphate bond

Answer 5

-41.2kJ/mol

Question 6

Advantages of the creatine kinase system

Answer 6

Rapid response for ATP generation

Good for short, strenuous exercise

Question 7

Disadvantages of the creatine kinase system

Answer 7

Limited supply of creatine (used up within 20-30 minutes)

Small yield of ATP per substrate molecule compared to ETC

Question 8

Five requirements of ATP synthesis in mitochondria

Answer 8

(1) High energy intermediates
(2) Transport of intermediates into the mitochondrial matrix
(3) ETC
(4) ATP synthase
(5) Translocase to deliver ATP to cytosol

Question 9

How fatty acids enter mitochondria

Answer 9

Via the carnitine shuttle system

Question 10

How pyruvate enters mitochondria

Answer 10

Via the link reaction; becomes acetyl-CoA

Question 11

List five electron carriers

Answer 11

1. Incorporation into numerous biological membranes
2. NADH, NADPH, FADH2
3. Ubiquinones
4. Transition metal complexes (e.g. Fe2+/Fe3+)
5. Within proteins (e.g. iron-sulphur complexes, porphyrins)

Question 12

How many electrons can NAD+ accept

Answer 12

Two, becoming NADH

Question 13

What NAD stands for

Answer 13

Nitotinamide adenine dinucleotide

Question 14

What FAD stands for

Answer 14

Flavin adenine nucleotide

Question 15

How many electrons can FAD accept

Answer 15

Two, becoming FADH2 (accepts hydride and a proton)

Question 16

Ubiquinone is derived from what?

Answer 16

Quinone (added an isoprenoid tail)

Question 17

Number of repeating units in isoprenoid tails in mammals?

Answer 17

10

Question 18

How quinone takes up electrons to become ubiquinone

Answer 18

Two carboxyl groups become hydroxyl groups (reduction). First stage results in one oxygen group forming a free radical.

Question 19

Structure of porphyrin

Answer 19

Four pyrole rings (five-membered rings containing a nitrogen) connected by methene bridges, with a Fe in the middle

Question 20

Three types of iron-sulphur clusters as electron carriers

Answer 20

1. Single Fe atom connected by a tetrahedral co-ordination of -SH groups
2. Two Fe irons connected to each other by two S atoms and each connected to the phosphate backbone by two S atoms [2Fe-2S]
3. Four Fe atoms, each connected to a single S atom connected to the phosphate backbone, and three other S atoms connected to the other Fe atoms [4Fe-4S]

Question 21

Two states of iron in iron-sulphur complexes

Answer 21

Fe2+ / Fe3+