Glycolysis

Question 1

Major pathway for glucose metabolism that converts glucose into 3 carbon compounds to provide energy

Answer 1

Glycolysis

Question 2

Site of glycolysis

Answer 2

CYTOSOL

Question 3

Substrate of glycolysis

Answer 3

GLUCOSE

Question 4

End products of glycolysis

Answer 4

2 molecules of either pyruvate or lactate

Question 5

Step that is Rate Limiting

Answer 5

Fructose 6 phosphate –> Fructose 1,6-bisphosphate

PHOSPHOFRUCTOKINASE

Question 6

3 Important Steps in Glycolysis

Answer 6

Step 1: Phosphorylation of glucose

Step 2: Phosphorylation of fructose 6-phosphate

Step 3: Formation of Pyruvate

Question 7

Found in most tissues

Inhibited by glucose 6-phosphate

LOW Km, HIGH affinity
LOW Vmax

Answer 7

Hexokinase

Question 8

Found in LIVER and ISLET cells of PANCREAS

Inhibited by fructose 6-phosphate

HIGH Km, LOW affinity
HIGH Vmax

Liver activity induced by insulin

Answer 8

Glucokinase

acts only when glucose is very high >100 mg/dL

Question 9

Most POTENT activator of PFK-1

Answer 9

Fructose 2,6 BP

Question 10

2 steps in glycolysis that produce ATP via substrate level phosphorylation

Answer 10

1,3 bisphosphoglycerate –> 3 phosphoglycerate
PHOSPHOGLYCRTAE KINASE

Phosphoenolpyruvate –> pyruvate
PYRUVATE KINASE

Question 11

Oxidation reaction that passes electrons to NAD+ to make NADH

Answer 11

Glyceraldehyde-3-phosphate –> 1,3 bisphosphoglycerate

GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE

Question 12

Major fate of pyruvate in lens, cornea, kidney (medulla), testes, RBCs, WBCs

Answer 12

Anaerobic glycolysis

pyruvate –> LACTATE
lactate dehydrogenase

NADH - used to REDUCE pyruvate to lactate

Question 13

No. of ATPs from Aerobic glycolysis

Answer 13

7 ATPs

Question 14

No. of ATPs from anaerobic glycolysis

Answer 14

2 ATPs

Question 15

Cells w/ mitochondria

Cells w/ adequate O2 supply

Answer 15

Aerobic Glycolysis

END PRODUCT: Pyruvate

Question 16

Cells w/o mitochondria

Cells w/o adequate O2 supply

Answer 16

Anaerobic Glycolysis

END PRODUCT: Lactate

Question 17

Number of ATPs generated

Answer 17

From Aerobic Glycolysis - 7 ATP

From Pyruvate Dehydrogenase - 2 NADH = 5 ATP

From TCA cycle (2 acetyl CoA from 1 mol of glucose) - 2x10 = 20 ATP

NET ATP = 7+5+20 = 32 ATP

Question 18

Found in RBCs where the reaction catalyzed by phosphoglycerate kinase is bypassed

Answer 18

RAPAPORT LUEBERING SHUNT PATHWAY

1,3 BPG –> 2,3 BPG
BIPHOSPHOGLYCERATE MUTASE

Question 19

Fates of Pyruvate

Answer 19

To Glucose (Gluconeogenesis)

To Lactate (Lactate dehydrogenase)

To Oxaloacetate (Pyruvate Carboxylase)

To Acetyl CoA (Pyruvate Dehydrogenase)

To Alanine (Alanine Amino Transferase)

Question 20

Coenzymes of PYRUVATE DEHYDROGENASE COMPLEX

Pyruvate –> Acetyl CoA

Answer 20

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Thiamine pyrophosphate
Lipomide
Coenzyme A (Pantothenic acid)
FAD
NAD+

Question 21

MC enzyme defect in glycolysis

Answer 21

Pyruvate kinase

HEMOLYTIC ANEMIA

Question 22

MCC of congenital LACTIC ACIDOSIS

Answer 22

Pyruvate dehydrogenase deficiency

x-linked dominant
increased lactate + decreased acetyl CoA –> psychomotor retardation and death

TREATMENT: ketogenic diet

Question 23

Fate of Acetyl CoA

Answer 23

FA Synthesis
Ketone Body Synthesis
Cholesterol Synthesis
TCA cycle

CANNOT BE CONVERTED TO GLUCOSE

Question 24

Coenzyme Prosthetic Groups

Answer 24

Thiamine diphosphate of E1 (pyruvate decarboxylase)

Lipoic acid of E2 (dihydrolipoyl transacetylase)

FAD of E3 (dihydrolipoyl dehydrogenase)

Question 25

Coenzyme Cosubstrates Groups

Answer 25

CoA

NAD+

Question 26

The MC form of PDHC deficiency is caused by mutations to

Answer 26

Thiamine diphosphate of E1 (pyruvate decarboxylase)

Question 27

End products that INHIBIT PDH COMPLEX

Answer 27

Acetyl CoA

NADH

Question 28

Covalent modification of PDH Complex

Answer 28

ACTIVE in DEphosphorylated state

INACTIVE in PHOsphorylated state

Question 29

PDH is PHOSPHORYLATED (inactivated) by

Answer 29

PDH KINASE
-activated in increase in
ATP/ADP
Acetyl CoA/CoA
NADH/NAD

Question 30

PDH is DEPHOSPHORYLATED (activated) by

Answer 30

PDH PHOSPHATASE

-activated by INSULIN