63. The Catabolism of pyruvate

Question 1

what is NAD+ derived from

Answer 1

niacin, an essential vitamin B3

Question 2

Glycolysis reduces NAD+ to

Answer 2

NADH + H+

Question 3

NADH must be re-oxidised to NAD+ or glycolysis cannot continue
Therefore, NAD+ is regenerated in the final stage of glucose catabolism which is ……

Answer 3

the electron transport chain

Question 4

where does the citric acid cycle take place

Answer 4

the matrix of the mitochondria

Question 5

where does the electron transport chain take place

Answer 5

the inner membrane of the mitochondria

Question 6

how does pyruvate enter the mitochondrial matrix

Answer 6

• H+ gradient from cytosol to matrix
• The pyruvate has to get in via a Pyruvate transporter and needs a H+/pyruvate symport to facilitate diffusion
• A similar process regulates ADP, ATP &inorganic phosphate (Pi)movement into and out of mitochondria

Question 7

In the matrix what is pyruvate being converted into

Answer 7

Acetyl - coA

Question 8

In the matrix after pyruvate is converted into acetyl coA can it go back to pyruvate

Answer 8

no it is an irreversible reaction

Question 9

what are the 3 enzymes called in the citric acid cycle

Answer 9

Pyruvate dehydrogenase,

Dihydrolipoamide acyltransferase,

Dihydrolipoyl Dehydrogenase

Question 10

what are the three names for this cycle

Answer 10

Citric acid cycle
Krebs Cycle
TCA (Tricarboxylic acid cycle)

Question 11

citrate is made up of ho many molecules

Answer 11

6

Question 12

oxaloacetate is made up of how many molecules

Answer 12

4

Question 13

what are the products of TCA

Answer 13

3 NADH
1 FADH2
2 CO2
1 GTP

Question 14

ll enzymes of the TCA cycle are located in the mitochondrial matrix, apart from:

Answer 14

• Succinate dehydrogenase …

Question 15

if the supply of pyruvate/oxaloacetate is limited (no glycolysis) the acetyl coA is diverted to ???

Answer 15

Ketones