Krebs/Citric Acid Cycle Flashcards
How does the pyruvate get into the mitochondria?
Active transport across the membrane
What does the link reaction, before the Krebs cycle, do?
Through oxidative decarboxylation, the pyruvate is converted into acetyl CoA.
Where does the “oxidative” part come from in the link reaction?
The removal of hydrogen, which is then accepted by NAD+, which becomes NAD+H +.
Where does the “decarboxylation” part of the link reaction come from?
The removal of carbon dioxide, which is removed by CoA and then is diffused out of the cell.
What happens after the decarboxylation of each pyruvate (in the link reaction)?
The remaining two-carbon molecule (acetyl group) reacts with reduced coenzyme A. At the same time one NADH+H is formed.
What are two hydrogen carrying enzymes?
NADH+ and FADH2
How many carbon dioxides are produced from each acetyl group formed in the link reaction during the Kreb Cycle?
Two carbon dioxides.
What’s the difference between cirtric acid and citrate?
Citrate is not dissolved in water, so it is the IONIZED form of citric acid.
How is citrate made in the first step of the Kreb’s cycle?
2-carbon Acetyl CoA binds with the 4-c sugar oxaloacetate and bind the six-carbon sugar (citrate).
How does citrate reduce to a 5-carbon molecule in step two of the Kreb’s cycle?
Citrate oxidizes: NAD+ picks up the e- and H (which is reduction–making bonds), and then carbon dioxide is released, leaving one less carbon.
How does the five-carbon molecule reduce to a four-carbon molecule in step three of the Kreb’s cycle?
The 5-carbon sugar is oxidized. This produces one carbon dioxide, NADH+H, and one ATP (from the form of GTP).
What happens in step four of the Kreb’s cycle in order to be returned to the original oxaloacetate state?
The four-c is rearranged when FAD becomes FADH2, and when NAD+ becomes NADH+H.
How many times can the Kreb’s cycle go around with one glucose molecule?
Two times because each pyruvate produces one acetyl CoA.
What is the link reaction?
An oxidative decarboxylation.
Name the molecules that conserve the most energy from the citric acid cycle’s redox reactions.
NADH and FADH2
