Exam 2: Krebs Cycle

Question 1

Step 1: What happens?

Answer 1

Acetyl is attached to oxaloacetate, forming citrate (6 carbons)

Question 2

Step 2: What happens?

Answer 2

Citrate re-arranges to isocitrate (6 carbons)

Question 3

Step 3: What happens?

Answer 3

Isocitrate is oxidized to α-ketoglutarate. CO2 released, NADH formed (5 carbons)

Question 4

Step 4: What happens?

Answer 4

α-ketoglutarate is oxidized…combines with CoA to form succinyl CoA…CO2 released NADH formed (4 carbons)

Question 5

Step 5: What happens?

Answer 5

Succinyl CoA breaks down to CoA and succinate (4 carbons). Since this is exergonic, this drives formation of GTP from GDP and P. GTP can transfer phosphate to make ATP.

Question 6

Step 6: What happens?

Answer 6

Succinate is oxidized into fumarate (4 carbons). FADH2 is formed.

Question 7

Step 7: What happens?

Answer 7

Fumarate and water make malate (4 carbons)

Question 8

Step 8: What happens?

Answer 8

Malate is oxidized into oxaloacetate (4 carbons). NADH is made.

Question 9

Where does the Krebs cycle occur?

Answer 9

Matrix of mitochondria

Question 10

In which steps are NADH produced from the reduction of NAD+ in TCAC?

Answer 10

Steps 3, 4, and 8

Question 11

In which steps are CO2 formed in TCAC?

Answer 11

Steps 3 and 4

Question 12

In which steps are FADH2 produced from the reduction of FAD?

Answer 12

Step 6

Question 13

Final products from 1 glucose (2 TCAC)?

Answer 13

2 FADH2, 6 NADH, 4 CO2, 2 ATP

Question 14

How many times does the cycle occur?

Answer 14

Twice

Question 15

What is the acronym to rememeber the 8 compounds?

Answer 15

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