AP BIOLOGY

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CELL RESPIRATION

THE KREBS CYCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In the introductory transitional reaction prior to entering the Krebs Cycle, each pyruvate molecule loses electrons, hydrogen ions, and a carbon, forming an energy-rich molecule of
A
Acetyl-CoA
B
Glucose
C
ATP
D
Malate
Explanation: 

Detailed explanation-1: -Prior to entry into this cycle, pyruvate must be converted into a 2-carbon acetyl-CoenzymeA (acetyl-CoA) unit. Figure 15.2. 1: After glycolysis, two 3-carbon pyruvates enter the mitochondria, where they are converted to two 2-carbon acetyl-CoenzymeA (CoA) molecules. Acetyl-CoA then enters the Krebs Cycle.

Detailed explanation-2: -The Krebs, or citric acid, cycle. Pyruvate, derived from glycolysis, is firstly converted into acetyl-CoA (2-C) which is subsequently condensed with oxaloacetate (4-C) to form the 6-C compound citrate.

Detailed explanation-3: -The eight steps of the cycle are a series of chemical reactions that produces two carbon dioxide molecules, one ATP molecule (or an equivalent), and reduced forms (NADH and FADH2) of NAD+ and FAD+, important coenzymes in the cell.

Detailed explanation-4: -10 NADH (including 2 from glycolysis)

There is 1 question to complete.
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