4_1Gluconeogenesis

Question 1

What are the 4 main regulation points of glycolysis?

Answer 1

1) GK, 2) PFK1, 3) F(2,6)bPase/PFK2, 4) PK, 5) PDH

Question 2

What function of PFK2/F26bPase is functional with phosphorylation?

Answer 2

F26bPase

Question 3

What is the active form of PFK-2?

Answer 3

dephosphorylated

Question 4

What is the active form of F26bPase?

Answer 4

phosphorylated

Question 5

What is the active form of PK?

Answer 5

phosphorylated

Question 6

What is the active form of PDH?

Answer 6

dephosphorylated

Question 7

What are the glycolytic enzymes?

Answer 7

1) GK, 2) PGI, 3) PFK1, 4) Aldolase, 4) tpi, 5) G3PDH, 6) PGK, 7) PGM, 8) Enolase; 9) PK; initation of TCA = PDH

Question 8

What glycolytic steps require energy?

Answer 8

1, 2, 6, 7, 10

Question 9

What glycolytic steps are regulated?

Answer 9

GK, PFK-1, PK, PDH (1, 3, 10+) and PFK2

Question 10

What is the key regulatory enzyme in glycolysis?

Answer 10

pfk1

Question 11

How is GK regulated?

Answer 11

induced by insulin; high Km for glucose; cannot do reverse;;; also inhibited by G6P directly

Question 12

How is PFK-1 regulated?

Answer 12

allosterically + (AMP, ADP, F26bP), allosterically - (ATP, citrate)

Question 13

How is F26bPase regulated?

Answer 13

inhibited by F2,6bP and AMP

Question 14

How is PK regulated?

Answer 14

activated by phosphorylation and F16bP; inhibited by Ala and ATP

Question 15

What are the non-reversible steps of glycolysis?

Answer 15

GK, PFK1, PK

Question 16

What gluconeogenetic enzyme replaces PK?

Answer 16

PC and PEPCK

Question 17

What gluconeogenetic enzyme replaces PFK1?

Answer 17

FBPase

Question 18

What gluconeogenetic enzyme replaces GK?

Answer 18

G6Pase

Question 19

What are the 4 key UNIQUE regulatory enzymes of gluconeogenesis?

Answer 19

PC, PEPCK, F16bP, G6Pase

Question 20

Where is PEPCK located?

Answer 20

mitochondria or cytosol

Question 21

Where is PC located?

Answer 21

in mitochondria

Question 22

How is stress gluconeogenesis triggered?

Answer 22

cortisol and epinephrine

Question 23

What factors stimulate gluconeogenesis?

Answer 23

1) prolonged exercise; 2) high protein diet; 3) stress

Question 24

How is gluconeogenesis regulated (in general)?

Answer 24

1) by availability of substrate, 2) by key enzymes

Question 25

What is the energy cost per mole of glucose?

Answer 25

12 ATP

Question 26

What are the energy requiring steps in gluconeogenesis and how much?

Answer 26

1) PC = 2 ATP; 2) PEPCK = 2 GTP; 3) PGK = 2 ATP; 4) G3PDH = 2 NADH

Question 27

How many ATPs = 1 NADH?

Answer 27

3

Question 28

How is PDH regulated?

Answer 28

allosterically + (pyruvate, CoASH, NAD+); allosterically - (acetyl-CoA, NADH); by kinase (kinase activated by acetyl-CoA, NADH, ATP); by phosphatase (activated by Ca++)

Question 29

How is PC activated?

Answer 29

by acetyl-CoA

Question 30

How is PEPCK activated?

Answer 30

induced when needed via GCG cAPK pathway

Question 31

How is F16bPase (FBP) regulated?

Answer 31

inhibited by F26bP and AMP; activated in their absence!; also induced via transcription

Question 32

How is G6Pase regulated?

Answer 32

reacts to the increased G6P that inhibits GK; not regulated otherwise

Question 33

Describe the PC mechanism.

Answer 33

1) ATP + COOH form phosphoanhydride, then de-CO2; 2) CO2-biotin, then decarboxylation; then biotin activates pyruvate for attack on CO2

Question 34

What is the PC reaction?

Answer 34

pyruvate + CO2 – OAA

Question 35

What is the PEPCK reaction?

Answer 35

OAA + GTP – PEP + GDP

Question 36

What are the ways that OAA can cross mito membrane to cytosol?

Answer 36

1) as malate (when NADH needed in cytosol); 2) as ASP; 3) as PEP from PEPCK

Question 37

What is the mechanism of the PEPCK reaction?

Answer 37

concerted de-CO2 of OAA and phosphorylation from GTP