7.4 Citric acid cycle

Question 1

What is the citric acid cycle?

Answer 1

a stage in which fuel (acetyl-CoA) molecules are completely oxidized to carbon dioxide and chemical energy is transferred into ATP by substate level phosphorylation to reduced carriers NADH and FADH2

Question 2

What is the citric acid cycle composed of?

Answer 2

8 reaction and called a cycle because the starting molecule is regenerated a the end.

Question 3

What occurs during the first reaction?

Answer 3

the 2-carbon acetyl group of acetyl-CoA is transferred to a 4 carbon molecule of oxaloacetate to form a 6- carbon molecule citric acid.

Question 4

what occurs during the cycle?

Answer 4

• 2 carbons are lost in the form of C02 which is coupled with the reduction of the electron carrier NAD+ to NADH
• NADH (3) and FADH2 (1) are produced in two additional redox reactions
• all electron carriers donate electrons to the electron transport chain.

Question 5

What occurs during the citric acid cycles subsrate level phosphorylation?

Answer 5

generates a molecule of GTP which transferred its terminal phosphate to a molecule of ADP to for ATP.

Question 6

what is yielded from a molecule of glucose during the citric acid cycle?

Answer 6

2 ATP
6 NADH
2 FADH2
for 2 rotations around the circle