Exam 2 Lecture 16 Gluconeogenesis

Question 1

whole body needs about _ g glucose per day

Answer 1

160 g

Question 2

daily glucose requirement of brain is about _ g

Answer 2

120 g

Question 3

glucose present in body fluids is about _ g

Answer 3

20 g

Question 4

glucose readily available from glycogen is about _ g

Answer 4

190 g

Question 5

glycogen is the storage form of _

Answer 5

glucose

Question 6

glycogen is stored where

Answer 6

liver and the muscle

Question 7

what is the purpose of a glycogen reserve?

Answer 7

the reserve of 190 g is sufficeint to meet glucose needs for about a day (fasting)

Question 8

gluconeogenesis occurs where?

Answer 8

liver and kidney

Question 9

Major 3 precursors of gluconeogenesis:

Answer 9

1. lactate
2. amino acids
3. glycerol

Question 10

what is the 1st step in gluconeogenesis?

Answer 10

pyruvate first converted to oxaloacetate (OAA)

Question 11

pyruvate is converted into OAA via

Answer 11

enzyme pyruvate carboxylase (PC)

Question 12

why is the compartmentalization of PC into the mitochondria important?

Answer 12

malate shuttle transports OAA to cytoplasm

Question 13

what is the 2nd step in gluconeogenesis?

Answer 13

OAA converted into PEP

Question 14

OAA converted into PEP via?

Answer 14

phosphoenolpyruvate carboxykinase

Question 15

what is the 3rd step in gluconeogensis?

Answer 15

PEP converted into 2-PG

Question 16

PEP converted into 2-PG via?

Answer 16

enolase (same as in glycolysis)

Question 17

what is the 4th step in gluconeogenesis?

Answer 17

2-PG converted into 3-PG

Question 18

2-PG converted into 3-PG via

Answer 18

phosphoglycerate mutase (same as in glycolysis)

Question 19

what is the 5th step in gluconeogenesis?

Answer 19

3-PG converted into 1,3-BPG

Question 20

3-PG converted into 1,3-BPG via?

Answer 20

phosphoglycerate kinase (same as in glycolysis)

Question 21

what is the last step in gluconeogenesis?

Answer 21

1,3-BPG into GAP

Question 22

1,3-BPG into GAP via?

Answer 22

glyceraldehyde 3-phosphate dehydrogenase (same as in glycolysis) GAPDH

Question 23

From GAP to glucose:

GAP + _ forms fructose 1,6-BP

Answer 23

DHAP

Question 24

glycerol enters the pathway via

Answer 24

DHAP

Question 25

lactate (and some amino acids) enters the pathway via

Answer 25

pyruvate

Question 26

amino acids enters the pathway via

Answer 26

OAA

Question 27

what is the rate limiting enzyme of gluconeogenesis?

Answer 27

Fructose 1,6-bisphosphatase

Question 28

From GAP to glucose: in 2nd step, Fructose 1,6-bisphosphatase breaks down _ into _

Answer 28

fructose 1,6-BP to F6P

Question 29

From GAP to glucose: in the 3rd step, F6P is _ to G6P via _

Answer 29

F6P is isomerized to G6P via phosphoglucose isomerase (same as in glycolysis)

Question 30

From GAP to glucose: in the last step, G6P forms free glucose by the action of _. Free glucose can leave liver and enter blood.

Answer 30

glucose 6-phosphatase

Question 31

glucose 6-phosphatase is located where?

Answer 31

in the lumen of the ER

Question 32

gluconeogeneis "by-passes" the irreversible steps of glycolysis via what 4 enzymes NOT present in glycolysis?

Answer 32

1. pyruvate carboxylase (PC) 2. phosphoenolpyruvate carboxykinase 3. fuctose 1,6-bisphosphatase 4. glucose 6-phosphatase

Question 33

2 pyruvate enters into gluconeogenesis to form 1 molecule of _

Answer 33

glucose

Question 34

what are the 3 points of ATP/GTP consumption in gluconeogenesis?

Answer 34

1. converting pyruvate into OAA 2. converting OAA into PEP 3. converting 3-PG into 1,3-BPG

Question 35

gluconeogenesis and glycolysis are _ regulated

Answer 35

reciprocally regulated

Question 36

what are the modulators/activators in glycolysis

Answer 36

1. F-2,6-BP and AMP stimulates phosphofructokinase in glycolysis 2. F-1,6-BP stimulates pyruvate kinase in glycolysis

Question 37

what are the modulators/inactivators in glycolysis

Answer 37

1. ATP, citrate, and H+ de-stimulates phosphofructokinase in glycolysis 2. ATP and alanine de-stimulates pyruvate kinase in glycolysis

Question 38

what are the modulators/activators in gluconeogenesis

Answer 38

1. Citrate stimulates fructose 1,6-bisphosphatase in gluconeogenesis

Question 39

what are the modulators/inactivators in gluconeogenesis

Answer 39

1. F-2,6-BP and AMP de-stimulates fructose 1,6-bisphosphatase in gluconeogenesis 2. ADP de-stimulates PC and phosphoenolpyruvate carboxykinase

Question 40

glucagon, when released, stimulates a kinase or phosphatase?

Answer 40

kinase

Question 41

insulin, when released, stimulates a kinase of phosphatase?

Answer 41

phosphatase

Question 42

F6P is converted into fructose 2,6-BP via _

Answer 42

phosphofructokinase 2 (PFK2)

Question 43

PFK2 has what kind of domains?

Answer 43

a kinase and a phosphatase domain

Question 44

Fructose 2,6-BP is a strong signalling molecule for _

Answer 44

phosphofrutokinase (PFK; rate limiting step of glycolysis)

Question 45

the concentration of Fructose 2,6-BP is controlled what kind of enzyme?

Answer 45

a bi-functional enzyme with a kinase and a phosphatase domain: PFK2 and FBPase 2 (fructose bisphosphatase)

Question 46

T/F: Fructose 2,6-BP stimulates or inhibits glycolysis

Answer 46

true

Question 47

the activity of the bi-functional enzyme is regulated by what 2 hormones?

Answer 47

insulin and glucagon

Question 48

_ stimulates a phosphatase and PFK2 is activated so glycolysis is active

Answer 48

insulin stimulates a phosphatase and PFK2 is activated | *glucose is abundant*

Question 49

_ stimulates PKA and FBPase 2 is activated so glycolysis is inhibited and gluconeogenesis is stimulated

Answer 49

glucagon stimulates PKA and FBPase 2 is activated | *when blood glucose is scarce*

Question 50

The Cori Cycle: lactate is produced in skeletal muscle and RBCs and can be converted back to pyruvate in the _. This location does the reverse to make pyruvate into _ so it can be thrown back into the blood and muscle can pick it up.

Answer 50

liver glucose