Pyruvate Metabolism And Krebs Cycle

Question 1

What does pyruvate need too be converted into before it can enter into The Krebs Cycle

Answer 1

Acetyl CoA

Question 2

Enzyme that converts Pyruvate to Acetyl CoA

Answer 2

Pyruvate Dehydrogenase

Question 3

How does Pyruvate Dehydrogenase convert Pyruvate to Acetyl CoA?

Answer 3

Oxidative decarboxylation
H Removed so NADH Formed
Carbon removed as CO2 (irreversible)

Question 4

Where does the Krebs Cycle Take place

Answer 4

In Mitochondria

Question 5

Krebs cycle is an essential Catabolic/oxidative pathway for:

Answer 5

Sugars
Fatty Acids
Ketone Bodies
Alcohol
Amino acids

Question 6

Why does Krebs Cycle not function without Oxygen?

Answer 6

NAD+ and FAD can’t be regenerated

Question 7

Krebs Cycle Purpose/Function:

Answer 7

To Produce Oxidising Agents NADH And FADH2 for oxidative phosphorylation

Has Biosynthetic function (produce intermediates to supply biosynthetic pathways:
-Non essential amino acids
-Haem and glucose
-Fatty acids

Question 8

How is the Krebs Cycle Regulated in terms of signals

Answer 8

Krebs cycle needed so lots of ATP can be made
High energy signals inhibit it (ATP and NADH)
Low energy signals stimulate it (ADP and NAD+)

Question 9

Enzyme that regulates Krebs cycle

Answer 9

Isocitrate dehydrogenase (First irreversible step)

Question 10

Isocitrate Dehydrogenase activiation and inhibition

Answer 10

Allosteric
NADH inhibits
ADP Activates

Question 11

PDH is a large multi-enzyme complex needing coenzymes made from which Vitamin?

Answer 11

B Vitamins
Vitamin B1 deficiency = Bad for this

Question 12

How many Krebs Cycles per glucose molecule?

Answer 12

2
2 Acetyl CoA are produced per glucose

Question 13

How many important molecules are produced per glucose molecule in the Krebs cycle

Answer 13

2 CYCLES
6 NADH
2 FADH2
2 CO2
2 GTP (Basically ATP)