CAC

Question 1

What comes out of the citric acid cycle (per glucose)?

Answer 1

4 CO2
2 FADH2 ~2 ATP
6 NADH ~3 ATP
2 GTP

Question 2

How many carbons are delivered from oxaloacetate?

Answer 2

4C

Question 3

What are the two ways to cut C-C bonds?

Answer 3

alpha cleavage (2x in CAC)
beta cleavage   (aldolase in glycolysis)

Question 4

Some things about citrate synthase…

Answer 4

cannot lose acetate
when S binds; closes very tightly; big conformational change
“fuse” OA and acetyl to citrate

Question 5

Step 2

Answer 5

citrate ——> isocitrate (aconitase)

set up for alpha cleavage of CO2

Question 6

Step 3

Answer 6

oxidative decarboxylation
(oxidation leads to spontaneous removal of CO2 &
NAD+ —–> NADH)
isocitrate DH

Question 7

Step 4

Answer 7

alpha ketoGDH complex

same as PDH complex, except no kinase and phosphatase

Question 8

Why the need for GTP?

Answer 8

so [ATP] doesn’t build up and stop CAC

GDP + ATP —> ADP + GTP