Energy Transfers in and Between Organisms: Aerobic Respiration - Link Reaction

Question 1

Where does the link reaction occur?

Answer 1

• The mitochondrial matrix

Question 2

What is the link reaction?

Answer 2

• Converts the pyruvate produced in glycolysis to acetyl coenzyme A

Question 3

Describe each step of the link reaction

Answer 3

• Pyruvate (3C) is decarboxylated - one carbon atom removed through carbon dioxide
• Pyruvate is also oxidised to form acetate (2C) while NAD is reduced (NADH)
• Acetate combines with coenzyme A (coA), forming acetyl coenzyme A (acetyl coA)

Question 4

How many times does the link reaction occur per glucose molecule?

Answer 4

• 2 pyruvates are made for every glucose molecule that enters glycolysis
• Link reaction occurs twice for every glucose molecule

Question 5

What are the products of two link reactions (or one glucose molecule)?

Answer 5

• 2 acetyl coenzyme A
• 2 carbon dioxides
• 2 NADH (reduced NAD)

Question 6

Where does the 2 acetyl coenzyme A’s go?

Answer 6

• To the Kreb’s cycle

Question 7

Where does the 2 carbon dioxides go?

Answer 7

• Released as waste product

Question 8

Where does the 2 reduced NAD go?

Answer 8

• To oxidative phosphorylation

Question 9

How many carbons do each of the organic compounds in the link reaction contain?

Answer 9

• Pyruvate, 3C
• Acetate, 2C
• Acetyl coA, 2C in its backbone