ATP Production: TCA + Respiratory Chain

Question 1

What is the TCA cycle?

Answer 1

Final pathway for the oxidation of carbohydrates, lipids, and protein. Synthesizes ATP

Question 2

What are the 3 important products of the TCA cycle?

Answer 2

NADH
FADH2
ATP

Question 3

What is the irreversible route from glycolysis to the TCA cylce?

Answer 3

Formation of Acetyl CoA from Pyruvate

Question 4

Where is pyruvate converted to Acetyl CoA? Why?

Answer 4

The mitochondria because Acetyl CoA cannot cross the mitochondrial membrane

Question 5

What enzyme complex converts pyruvate to acetyl CoA? What vitamin is required?

Answer 5

Pyruvate dehydrogenase complex
Thiamin (Vit B1)

Question 6

What is the second irreversible step in the TCA cycle? What is the enzyme associated with this step?

Answer 6

OAA to Citrate via citrate synthase

Question 7

What steps of the TCA cycle yields NADH?

Answer 7

Isocitrate- alpha KG
Alpha-KG - succinyl CoA
Malate - OAA

Question 8

What step(s) of the TCA cycle yields ATP?

Answer 8

Succinyl CoA - Succinate

Question 9

What step(s) in the TCA cycle yields FADH2?

Answer 9

Succinate - Fumarate

Question 10

How many total ATP is produced by the TCA cycle alone?

Answer 10

9

Question 11

What enzyme in the TCA cycle can be inhibited by arsenic? what step does this enzyme facilitate?

Answer 11

alpha-KG dehydrogenase complex
alpha-KG - succinyl CoA

Question 12

What is the catabolic function of the TCA cycle?

Answer 12

Oxidation of acetyl CoA derived from carbohydrates, lipids, protein metabolism to produce ATP

Question 13

What are the anabolic functions of the TCA cycle? (3)

Answer 13

-Gluconeogenesis
-Fatty acid biosynthesis
-substrates fro amino acid synthesis

Question 14

Where does fatty acid biosynthesis take place?

Answer 14

cytosol

Question 15

How does acetyl CoA (which is produced in the mitochondria via pyruvate) leave the cell to take part in fatty acid biosynthesis? What is the key enzymes used to ensure this transfer completion?

Answer 15

It exits by conversion to citrate by citrate synthase, citrate crosses the membrane, then via citrate lyase converts back to acetyl CoA

Question 16

Where does the respiratory chain (electron transport) take place?

Answer 16

The mitochondrial membrane

Question 17

What is the job of the respiratory chain?

Answer 17

Oxidized reduced coenzymes (NADH, FADH2) produced in the TCA cycle and from fatty acid catabolism. Generation of ATP

Question 18

What respiratory chain component is inhibited by cyanide and carbon monoxide, causing total respiratory arrest and subsequent cell death?

Answer 18

Component IV

Question 19

How many total ATP is produced after TCA cycle and oxidative phosphorylation?

Answer 19

~32

Question 20

NADH cannot penetrate the mitochondrial membrane. How can it take part in the respiratory cycle? List the two ways and how they differ

Answer 20

• Glycerol 3- phosphate shuttle: present in skeletal muscle and brain. converts dihydroxyacetone to glycerol 3- phosphate via NADH & glycerol 3 phosphate dehydrogenase, thus place the electrons on Glycerol 3-P, this then crosses the membrane and is concerted back to dihydroxyacetone, releasing FADH2 which will enter the respiratory cycle
  -Malate Shuttle: OAA is converted to malate via NADH and malate dehydrogenase, malate crosses the membrane, and is converted back to OAA releasing NADH. Problem is OAA cannot cross the mitochondrial membrane so it is transaminated with glutamate to form alpha-KG which will cross readily.

Question 21

What complex is ATP finally synthesized?

Answer 21

Complex V

Question 22

What is used as energy in complex V to form ATP?

Answer 22

All the H+ that was pumped into the intermembrane space by the other complexes.