Controlling Cellular Respiration

Question 1

what is the third reaction of glycolysis catalyzed by?

Answer 1

the enzyme phosphofructokinase (PFK)

Question 2

what two things inhibit PFK activity

Answer 2

-ATP in high concentrations

-when citrate accumulates in the mitochondria some will leak back into the cytoplasm and also inhibit PFK, therefore, halting glycolysis

Question 3

what stimulates PFK activity

Answer 3

ADP in high concentrations or low ATP

Question 4

what does a high concentration of citrate signify about ATP?

Answer 4

that ATP concentration is high

Question 5

what two things does a high concentration of NADH indicate?

Answer 5

it indicates the electron transport chain is full of electrons and ATP production is high

Question 6

what does NADH inhibit?

Answer 6

NADH allosterically inhibits pyruvate decarboxylase and reduced the amount of Acetyl CoA fed into the Krebs cycle. This subsequently inhibits more NADH from being produced

Question 7

what happens to Acetyl CoA when the concentration of ATP is low

Answer 7

Acetyl CoA enters the Krebs Cycle

Question 8

why does step 6 in Glycolysis need oxygen?

Answer 8

step 6 of glycolysis requires NAD+ to produce NADH

Question 9

what happens to NAD+ at the glycerol phosphate shuttle?

Answer 9

NAD+ is recycled from the electron transport chain

Question 10

what happens if there is no oxygen?

Answer 10

without oxygen, step 6 of glycolysis becomes depleted of NAD+ and the whole process grinds to a halt

Question 11

what is the solution to NAD+ not being depleted?

Answer 11

the solution is the transfer the hydrogen atoms of NADH to other organic molecules instead of the electron transport chain