12.2 Link reaction and Krebs cycle

Question 1

location of link reaction

Answer 1

pyruvate actively transported to matrix in mitochondria

Question 2

link reaction equation

Answer 2

pyruvate + NAD +CoA -> acetyl CoA + NADH + CO2

Question 3

link reaction process

Answer 3

pyruvate is oxidised- losing a CO2 molecule and 2 hydrogens

hydrogens are accepted by NAD to form NADH

2C acetate combines with coenzymeA to produce acetylecoenzymeA

Question 4

krebs cycle process

Answer 4

2C acetyleconenzyme A combines with 4C to produce 6C molecule

in series of reactions, 6C loses CO2 and hydrogen to form 4C and single ATP from substrate level phosphorylation

4C molecule now recombines with acetyl CoA

Question 5

product from one pyruvate molecule from link reaction and krebs cycle

Answer 5

reduced coenzymes NAD and FAD

1molecule ATP

3 molecules CO2

Question 6

coenzymes

Answer 6

molecules that some enzymes require in order to function

Question 7

NAD

Answer 7

coenzyme

works with dehydrogenase enzymes
- catalyse removal of H atoms from substrates
- transfer to other molecules involved in oxidative phosphorylation

Question 8

4 reasons Krebs cycle is significatn

Answer 8

• breaks down macromolecules into smaller ones
• produce H atoms carried by NAD to electron transfer chain and provide energy for oxidative phosphorylation
• regenerates 4C molecules to combine with acetyl CoA
• source of intermediate compounds used by cells in manufacturing other important substances e.g. fatty acids, amino acids and chlorophyll