AP BIOLOGY

CELL RESPIRATION

THE KREBS CYCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
For the two pyruvates that enter from glycolysis, the Krebs cycles will yield:
A
1 ATP, 2 NADH, and 1 FADH2
B
1 ATP, 2 NADH, and 2 FADH2
C
1 ATP, 3 NADH, and 1 FADH2
D
2 ATP, 8 NADH, and 2 FADH2
E
2 ATP, 4 NADH, and 2 FADH2
Explanation: 

Detailed explanation-1: -Glycolysis produces two pyruvate molecules, four ATPs (a net of two ATP), two NADH, and two H2O. Therefore, without the presence of oxygen, glycolysis is the only process that can occur, and only two ATP molecules may be produced for each glucose molecule.

Detailed explanation-2: -For one cycle, two molecules of carbon, three molecules of NADH, one molecule of FADH2 and one molecule of ATP or GTP are produced.

Detailed explanation-3: -In eukaryotic cells, the pyruvate molecules produced at the end of glycolysis are transported into mitochondria, which are the sites of cellular respiration. There, pyruvate will be transformed into an acetyl group that will be picked up and activated by a carrier compound called coenzyme A (CoA).

Detailed explanation-4: -The two acetyl carbon atoms will eventually be released on later turns of the cycle; thus, all six carbon atoms from the original glucose molecule are eventually incorporated into carbon dioxide. Each turn of the cycle forms three NADH molecules and one FADH2 molecule.

There is 1 question to complete.