Lecture 4

Question 1

What are the three stages that aerobic respiration occurs at?

Answer 1

glycolysis (cytosol); krebs cycle (mitochondria); ETC

Question 2

true or false; the TCA cycle is involved in the breakdown of carbohydrates as well as lipids and proteins

Answer 2

true

Question 3

What are the two reducing powers that the TCA cycle produces

Answer 3

NADH and FADH2

Question 4

What does carrier molecule does the TCA cycle use?

Answer 4

oxaloacetate

Question 5

true or false; the complete oxidation of organic compounds cannot occur in the absence of oxygen

Answer 5

true

Question 6

true or false; the ATP yield per glucose molecule is 15 times greater than under anaerobic conditions

Answer 6

true

Question 7

What is the purpose of oxaloacetate?

Answer 7

acts as a carrier molecule for acetyl groups

Question 8

What happens during the first phase of the TCA cycle

Answer 8

oxidises both carbon atoms of acetyl CoA to produce CO2

and high energy electrons in the form of NADH

Question 9

What happens during the second phase of the TCA cycle

Answer 9

primarily concerned of the regeneration of oxaloacetate

FADH2, NADH , GTP

Question 10

What happens to the GTP produced

Answer 10

used to produce ATP by phosphoryltransfer to an ADP

Question 11

true or false; all the carbon molecules of the pyruvate is released as CO2

Answer 11

true

Question 12

where did pyruvate release CO2 and how many?

Answer 12

pyruvate dehydrogenase complex (1 CO2)
Krebs cycle (2 CO2 released)

Question 13

what overall happens from step 1-4 in the krebs cycle

Answer 13

breakdown to release of CO2 and NADH

Question 14

What overall happens from 5-8 in the krebs cycle

Answer 14

regeneration of oxaloacetate

Question 15

regulation of krebs cycle: what is the key enzyme

Answer 15

isocitrate dehydrogenase

Question 16

why is isocitrate dehydrogenase a key enzyme

Answer 16

this is because; it is important to maintain an adequate level of citrate; since citrate is able to be transported into the cytosol, where it is an inhibitor of glycolysis and an activator of fatty acid synthesis

-also used to generate acetyl CoA for use in lipid biosynthesis

Question 17

what is isocitrate dehydrogenase inhibited by?

Answer 17

high levels of NADH

Question 18

what is isocitrate dehydrogenase stimulated by?

Answer 18

high levels of NAD+ and FAD

Question 19

What inhibits the pyruvate dehydrogenase complex

Answer 19

high levels of acetyl CoA, NADH, ATP