Carbohydrate Metabolism

Question 1

Low Km and Low Vmax; inhibited by G6P

Answer 1

Hexokinase

Question 2

High Km and high Vmax; inhibited by F6P

Answer 2

Glucokinase

Question 3

Inhibitors of PK (pyruvate kinase)

Answer 3

ATP, Glucagon, Alanine

Question 4

Stimulators of PK (pyruvate kinase)

Answer 4

Insulin, F1-6 BP; dephosphorylation

Question 5

Defects in glycolytic enzymes (such as PK, phosphoglucoisomerase and triosephosphate isomerase) malfunction of ATP pumps, intracellular NA+ concentration increases, cell swells, and bursts

Answer 5

Hemolytic anemia

Question 6

Malfunction of GLUT 2; Impaired transport of fructose, glucose and galactose; fasting hypoglycemia

Answer 6

Fanconi Bickel

Question 7

Deficiency in PFK 1 (rate limiting enzyme of glycolysis)

Answer 7

Tauri Disease

Question 8

Rate limiting enzyme of gluconeogenesis

Answer 8

Fructose 1, 6 Bisphosphatase

Question 9

Steps in Gluconeogenesis different from glycolysis

Answer 9

Pyruvate-Phosphoenolpyruvate (Pyruvate Carboxylase) and (PEPCK) OAA to PEP
Fructose 1,6 BP-Fructose 6P (Fructose 1,6 Bisphosphatase)
Glucose 6 Phosphate-Glucose (Glucose 6 Phosphatase)

Question 10

Positive enzymatic regulators of gluconeogenesis

Answer 10

Malate Dehydrogenase; PEPCK, Pyruvate carboxylase, and fructose 1,6 bisphosphatase, glucose 6 phosphatase

Question 11

Positive regulators of gluconeogenesis

Answer 11

Citrate, cortisol, thyroxine, acetyl coA

Question 12

Negative regulators of gluconeogenesis

Answer 12

ADP, AMP, Fru 2-6 BP

Question 13

Fructose 1,6 BP Deficiency

Answer 13

Can’t convert Fructose 1,6 BP to Fructose 6 Phosphate
Hypoglycemia
Lactic acidosis
Ketosis
Hyperventilation after artificial sweeteners

Question 14

Deficiency in glucose 6 phosphatase

Fasting hypoglycemia

Answer 14

Von Gierke Disease

Question 15

Fructose Metabolism

Answer 15

Usually used for fatty acid synthesis

Converted to sorbitol (sorbitol dehydrogenase) and to glucose (aldol reductase)-used for glycolysis

Question 16

Galactose metabolism

Answer 16

GALT-rate limiting enzyme (converts Galactose 1 phosphate to Glucose 1 phosphate); in liver can convert to glucose 6 phosphate

Question 17

Deficiency in GALT; can cause cataracts

Answer 17

Galactosemia

Question 18

Regenerates glutathione (important in detoxifying H2O2)

Answer 18

NADPH (made from PPP)

Question 19

Inhibits glycogen breakdown

Answer 19

Insulin, GLUT 4, PKB, GSK3

Question 20

Stimulates glycogen breakdown

Answer 20

G protein, cAMP, PKA, PP1, PPK

Question 21

Defective glycogen synthase

Answer 21

GSD0

Question 22

Defective acid maltase

Can’t lysosomally degrade glycogen

Answer 22

Pompe (GSD II

Question 23

Deficiency in debranching enzyme

Light hypoglycemia and hepatomegaly

Answer 23

GSD III/ CORI

Question 24

Deficient branching enzyme
Cirrhosis
Death by age 5

Answer 24

GSD IV/ Andersen

Question 25

Deficiency in muscle glycogen phosphorylase | Exercise intolerance

Answer 25

GSD V/ MCARDLE

Question 26

Deficiency in liver glycogen phosphorylase

Answer 26

GSD VI/ HERs