Carbs II

Question 1

In the absence of oxygen, what substrate serves as an electron acceptor to regenerate NAD? What product is formed?

Answer 1

Pyruvate. Lactic acid.

Question 2

What cells rely exclusively on glycolysis?

Answer 2

red blood cells

Question 3

What is the first reaction of glycolysis?

Answer 3

hexokinase converts glucose into glucose-6-phosphate

Question 4

What is the second reaction of glycolysis?

Answer 4

glucose phosphate isomerase converts glucose-6-phosphate into Fructose-6-phosphate

Question 5

What is the third reaction of glycolysis?

Answer 5

phosphofructokinase converts F6P into F16bP

Question 6

What is the fourth step of glycolysis?

Answer 6

F16bP is split into DHAP and GAP by fructose bisphosphate aldolase

Question 7

What enzyme converts DHAP to GAP?

Answer 7

triose phosphate isomerase

Question 8

What enzyme converts GA3P into 13bPG?

Answer 8

GAPDH

Question 9

What enzyme of glycolysis produces a reducing equivalent?

Answer 9

GAPDH

Question 10

What reaction does phosphoglycerate kinase catalyze?

Answer 10

1,3bPG to 3-phosphoglycerate kinase

Question 11

What reaction to phosphoglyceromutase catalyze?

Answer 11

3-phosphoglycerate to 2-phosphoglycerate

Question 12

What reaction does enolase catalyze?

Answer 12

2-phosphoglycerate to phosphoenolpyruvate

Question 13

What reaction does pyruvate kinase catalyze?

Answer 13

phosphenolpyruvate into pyruvate

Question 14

What two reactions of glycolysis yield ATP?

Answer 14

pyruvate kinase and phosphoglycerate kinase

Question 15

What is the function of fructokinase?

Answer 15

to phosphoryplate fructose into F1P

Question 16

What is the fate of F1P?

Answer 16

Conversion to DHAP and glyceraldehyde

Question 17

What is the fate of fructose in muscle?

Answer 17

Fructose will be slowly converted to F6P by hexokinase

Question 18

What hormone’s activity is independent of insulin? What are the implications of this?

Answer 18

Fructokinase. Diabetics can tolerate fructose as well as non-diabetics.

Question 19

What tissue does hexokinase convert fructose into fructose-6-phosphate?

Answer 19

muscle

Question 20

What tissue does fructokinase convert fructose into F1P?

Answer 20

liver

Question 21

What does essential frustosuria is caused by a deficiency in what enzyme?

Answer 21

liver fructokinase

Question 22

What is hereditary fructose intolerance?

Answer 22

a defective Aldolase B

Question 23

What is the function of Aldolase B?

Answer 23

to convert fructose-1-phosphate into glyceraldehyde and DHAP

Question 24

During aldolase B deficiency, what product accumulates in the liver?

Answer 24

fructose-1-phosphate

Question 25

What is galactosemia?

Answer 25

failure to utilize galactose in glycolysis

Question 26

What are the three regulated enzymes of glycolysis?

Answer 26

hexokinase, phosphofructokinase, pyruvate kinase

Question 27

What two enzymes of glycolysis are regulated by insulin?

Answer 27

hexokinase and pyruvate kinase

Question 28

What is the function of F26bP?

Answer 28

F26bP acts as an accelerator of glycolysis and an inhibitor of gluconeogenesis

Question 29

What does high [cAMP] signal?

Answer 29

fasting state

Question 30

What is the function of cAMP in relation to its effects on metabolism?

Answer 30

cAMP functions to reduce glucose consumption by glycolysis

Question 31

What does insulin do to cAMP levels?

Answer 31

Insulin inhibits cAMP formation

Question 32

How does glucagon affect cAMP levels?

Answer 32

glucagon acts to raise cAMP levels

Question 33

What second messenger inhibits PFK II?

Answer 33

PKA

Question 34

What are the two functions of F26bP?

Answer 34

to activate PFK I and to inhibit fructose bisphosphotase

Question 35

What two shuttle systems can the cell use to ensure NAD availability for glycolysis?

Answer 35

malate-asparate shuttle and the glycerol phosphate shuttle

Question 36

What tissues use the malate-aspartate shuttle?

Answer 36

liver and heart

Question 37

What tissues use the glycerol phosphate shuttle?

Answer 37

muscle and brain

Question 38

What molecule is transported to the liver during Cori cycle?

Answer 38

lactic acid is transported

Question 39

What happens to lactic acid in the liver during the Cori cycle?

Answer 39

lactic acid is converted to pyruvate

Question 40

What is the fate of pyruvate in the liver?

Answer 40

pyruvate is used to manufacture glucose

Question 41

What requires an NADH, pyruvate to lactate or lactate to pyruvate?

Answer 41

pyruvate to lactate requires an NADH

Question 42

Can liver failure highlight the effects of the Cori cycle?

Answer 42

yes. lactic acidosis can occur without a functioning liver.

Question 43

How are hemolytic anemia and glycolysis connected?

Answer 43

defects in glycolysis and highlighted in hemolytic anemia

Question 44

What is the most common hereditary enzymatic deficiency in glycolysis?

Answer 44

pyruvate kinase deficiency

Question 45

What do defects of any glycolytic enzyme do to the RBC?

Answer 45

lysis of the cells due to inability to maintain memrbane potential

Question 46

What glycolytic enzyme is affected by arsenate?

Answer 46

GAPDH