Gluconeogenesis

Question 1

Gluconeogenesis is creating new glucose from….

Answer 1

non-carbs

Question 2

What are the 5 substrates for gluconeogenesis?

Answer 2

1) glucogenic AAs
2) glycerol
3) pyruvate
4) lactate
5) intermediates of TCA

Question 3

Which AAs are glucogenic?

Answer 3

ALL standard AAs EXCEPT lysine and leucine (so theres 18 glucogenic AAs)

this means these AAs can change to glucose

Question 4

Muscles that are breaking down for protein is a major substrate for gluconeogenesis. Which muscles breakdown first?

Answer 4

skeletal muscles that are not used or infrequently used are broken down to get glucogenic AAs for gluconeogenesis

Question 5

How are the intermediates from TCA cycle used in gluconeogenesis?

Answer 5

Glucogenic AAs (everything besides lys and leu) can have the amino group removed and become an intermediate for TCA, which will then allow it to become glucose

ex: aspartate can change to OAA and then go through malate shuttle

Question 6

How long does glycerol last and where is it found?

Answer 6

12 hours and is found in fats/TG

Question 7

T/F: you get lactate from RBCs if you don’t exercise, and if you do exercise then lactate also comes from skeletal muscle

Answer 7

true

Question 8

Is this an oxidation reaction or reduction reaction?

pyruvate to lactate with LDH

Answer 8

reduction reaction

Question 9

Is this an oxidation reaction or reduction reaction?

lactate to pyruvate with LDH

Answer 9

oxidation reaction

Question 10

Glycogen is in the _____________ of liver. It can change to blood glucose

Answer 10

cytoplasm

Question 11

where does gluconeogenesis occur?

Answer 11

in mitochondria and cytoplasm of liver

Question 12

Which 2 enzymes are used in both glycogenolysis and and gluconeogenesis?

Answer 12

G6Pase and F1,6BPase

Question 13

There are 3 rate limiting steps in glycolysis. So in gluconeogenesis, it has to bypass all 3 rate limiting steps/enzymes. What are the 3 steps of glycolysis and RLEs?

Answer 13

step 1 of glycolysis with GK or HK

step 3 with PFK1

step 10 with pyruvate kinase

Question 14

What is required in gluconeogenesis to make 1 glucose?

Answer 14

-2 pyruvate
-6 ATP
-2 NADH

Question 15

What is gluconeogenesis stimulated by?

Answer 15

-glucagon
-hypoglycemia
-fasting

Question 16

T/F: gluconeogenesis is essentially the glycolytic pathway in reverse

Answer 16

true

Question 17

What are the 4 key enzymes in gluconeogenesis?

Answer 17

1) pyruvate carboxylase
2) PEP carboxykinase
3) F1,6BPase
4) G6Pase

all other enzymes are the same as in glycolysis

Question 18

Is gluconeogenesis an anabolic or catabolic reaction?

Answer 18

anabolic

Question 19

What pathways are most commonly involved in gluconeogenesis?

Answer 19

reverse glycolysis and TCA

Question 20

Which enzyme is only found in liver mitochondria and is why gluconeogenesis is in both mitochondria and cytoplasm?

Answer 20

pyruvate carboxylase

Question 21

First bypass of gluconeogenesis is 2 steps. What is the first step?

Answer 21

Pyruvate gets converted to OAA with pyruvate carboxylase (ABC enzyme)

note: this step requires biotin, 2 ATP, and carbon dioxide

Question 22

First bypass of gluconeogenesis is 2 steps. What is the second step?

Answer 22

OAA gets converted to PEP with PEP CK

note: 2 GTP is required and the reaction will release carbon dioxide

Question 23

Pyruvate has 2 ways to enter the TCA. What are they?

Answer 23

1) convert to acetyl CoA with pyruvate dehydrogenase (glycolysis/TCA)
2) convert to OAA with pyruvate carboxylase (gluconeogenesis)

Question 24

Where is PEP CK located?

Answer 24

in both cytoplasm and mitochondria

Question 25

Is PEP a VIP molecule?

Answer 25

yes

Question 26

2 pyruvate are used to make one glucose. What energy sources are needed to do this?

Answer 26

6 ATP (4 ATP, 2 GTP) and 2 NADH will be used to convert 2 pyruvate to 1 glucose

Question 27

2 glycerol 3 phosphates are used to make one glucose. What energy source is made?

Answer 27

2 NAD+

Question 28

2 lactates are converted to 2 pyruvate, which then makes 1 glucose. What energy is needed to do this?

Answer 28

lactate to pyruvate makes 2 NADH pyruvate to glucose uses 6 ATP and 2 NADH so the net energy LOSS is -6 ATP (was used)

Question 29

How much ATP is required for first bypass of gluconeogenesis?

Answer 29

2 ATP, 2 GTP (so 4 ATP)

Question 30

When cytosolic NADH levels are high, PEP is generated in the....

Answer 30

mitochondria

Question 31

What is the 2nd bypass of gluconeogenesis?

Answer 31

This reaction bypasses reaction 3 of glycolysis (catalyzed by PFK1)

Question 32

What is the 3rd bypass of gluconeogenesis?

Answer 32

Question 33

1 glucose makes 2 pyruvate. What energy sources are made?

Answer 33

2 ATP, 2 NADH

Question 34

To prevent the waste of a futile cycle, glycolysis and glucoenogenesis are....

Answer 34

reciprocally regulated

Question 35

At the first control point of glycolysis/ gluconeogenesis, If the energy demands of the cell are being met, the TCA cycle slows and __________ will accumulate

Answer 35

acetyl CoA

Question 36

High concentrations of acetyl coa inhibits _______ and activates _______

Answer 36

pyruvate dehydrogenase (PDH) and pyruvate kinase, pyruvate carboxylase (PC)

Question 37

What is the most important control step for gluconeogenesis?

Answer 37

2nd control step, to bypass PFK1 in glycolysis this is done with F1,6 biphosphatase this step is regulated by 2 mechanisms: -indicators of cell energy demand -hormones

Question 38

The second control step in gluconeogenesis is bypassing PFK1 with F1,6 BPtase. One of the mechanisms to regulate this is indicators of cell energy demand. What would elevated AMP do?

Answer 38

stimulate PFK1 but inhibit F1,6 BPtase When ATP is low, AMP is high, the cell does not expand energy in synthesizing glucose

Question 39

The second control step in gluconeogenesis is bypassing PFK1 with F1,6 BPtase. One of the mechanisms to regulate this is indicators of cell energy demand. What would elevated ATP do?

Answer 39

inhibit PFK1, stimulate F 1,6 BPtase when cellular ATP is high, AMP is low, glucose is not degraded to make ATP

Question 40

The second control step in gluconeogenesis is bypassing PFK1 with F1,6 BPtase. One of the mechanisms to regulate this is indicators of cell energy demand. What would elevated citrate do?

Answer 40

inhibit PFK1, stimulate F1,6 BPtase

Question 41

What 2 molecules inhibit PFK1 but stimulate F1,6 BPtase?

Answer 41

high ATP and citrate levels

Question 42

What hormones enhance gluconeogenesis by removing the inhibitory effects of F2,6 BP?

Answer 42

glucagon or epi

Question 43

When insulin increases, what 2 pathways are stimulated and 2 inhibited?

Answer 43

stimulated= glucogenesis and glycolysis inhibited= glycogenolysis and gluconeogenesis

Question 44

When glucagon increases, what 2 pathways are stimulated and 2 inhibited?

Answer 44

stimulated= glycogenolysis and gluconeogenesis inhibited= glucogenesis and glycolysis

Question 45

When ATP increases, what 2 pathways are stimulated and 2 inhibited?

Answer 45

stimulated= glucogenesis and gluconeogenesis inhibited= glycogenolysis and glycolysis

Question 46

When ADP/AMP increases, what 2 pathways are stimulated and 2 inhibited?

Answer 46

stimulated= glycogenolysis and glycolysis inhibited= glucogenesis and gluconeogenesis

Question 47

Glucagon and insulin will always overpower...

Answer 47

ATP and ADP