R 3

Question 1

overview of link

Answer 1

The end product of glycolysis is pyruvate
Pyruvate contains a substantial amount of chemical energy that can be further utilised in respiration to produce more ATP
When oxygen is available pyruvate will enter the mitochondrial matrix and aerobic respiration will continue

Pyruvate moves across the double membrane of the mitochondria via active transport

It requires a transport protein and a small amount of ATP

Once in the mitochondrial matrix pyruvate takes part in the link reaction

Question 2

where does link take place

Answer 2

The link reaction takes place in the matrix of the mitochondria

Question 3

why is it referred to as link

Answer 3

It is referred to as the link reaction because it links glycolysis to the Krebs cycle

Question 4

What is step one of Link

Answer 4

Pyruvate is oxidised by enzymes to produce acetate, CH3CO(O)- and carbon dioxide, requiring the reduction of NAD to NADH

Question 5

STEP 2 OF Link

Answer 5

Combination with coenzyme A to form acetyl coenzyme A (acetyl CoA)

Question 6

PRODUCTS OF LINK

Answer 6

Acetyl coA
Carbon dioxide (CO2)
Reduced NAD (NADH)

Question 7

VISUAL AID, reaction sequence

Answer 7

pyruvate + NAD + CoA → acetyl CoA + carbon dioxide + reduced NAD

Question 8

Role of coenzyme A

Answer 8

A co enzyme is an enzyme that helps an enzyme cary out it’s function.

Coenzyme A consists of a nucleoside (ribose and adenine) and a vitamin

CoA binds to the remainder of the pyruvate molecule (acetyl group 2C) to form acetyl CoA

supplies the acetyl group to the Krebs cycle where it is used to continue aerobic respiration