Carbohydrates

Question 1

Rate limiting step of glycolysis

Answer 1

F6P -> F1,6P

Phosphofructokinase 1

Question 2

NADPH producing reaction in glycolysis

Answer 2

G3P -> 1,3-BPG

G3P dehydrogenase

Question 3

Shuttle in liver, kidney, heart for NADH

Answer 3

Malate-Aspartate Shuttle

Question 4

NADH shuttle in skeletal muscle and brain

Answer 4

Glycerol phosphate shuttle

1 NADH: 2 ATP

Question 5

Strictly glycolytic organs (produces lactate)

Answer 5

RBCs
Lens
Cornea
Kidney medulla
Testis
WBCs

Question 6

Arsenic poisoning affects which enzymes?

Answer 6

Pryruvate dehydrogenase

Glyceraldehyde 3 phosphate dehydrogenase (NADH producing step)

Question 7

Most common enzymatic defect in glycolysis?

Answer 7

Pyruvate kinase deficiency
For last step: PEP-> pyruvate
Sx: chronic hemolytic anemia

Question 8

Pyruvate dehydrogenase cofactors?

Answer 8

Pyruvate-> acetyl CoA

Thiamine pyrophosphate
FAD
NADH
coenzyme A (contains pantothenic acid)
Lipoid acid

Question 9

Where does TCA cycle occur?

Answer 9

Mitochondrial matrix

Question 10

Pasaway enzyme that stays in the IMM while everyone is in the matrix?

Answer 10

Succinate dehydrogenase

Succinate -> fumarate

Question 11

Rate limiting step in TCA cycle?

Answer 11

Isocitrate -> a-ketoglutarate

Isocitrate dehydrogenase

Question 12

What enzyme does rat kill (fluoroacetate) affect?

Answer 12

Aconitase

Citrate-> isocitrate

Question 13

GTP is produced in what reaction?

Answer 13

Succinyl CoA -> succinate
Succinate thiokinase

Ang Gatas Galing sa SU-SU.

Question 14

NADH is produced in which steps of the TCA cycle?

Answer 14

Isocitrate -> a-ketoglutarate
a-ketoglutarate -> succinyl CoA
Malate-> oxaloacetate

• pyruvate -> acetyl CoA

Question 15

FADH2 is produced in which TCA step?

Answer 15

Succinate -> fumarate

Succinate dehydrogenase

Question 16

Which TCA intermediates can be redirected somewhere else?

Answer 16

Citrate
Succinyl CoA
Malate

Question 17

ATP yield from TCA cycle (from pyruvate)

Answer 17

15!! (X2 if counting per glucose molecule)

Question 18

Where does gluconeogenesis occur?

Answer 18

Liver (90%) and Kidneys (10%)

Mitochondria and cytoplasm

Question 19

Cori cycle is for?

Answer 19

Lactate from muscles -> glucose
Occurs at the liver
Uses 4 ATP

Question 20

What cofactor is needed in carboxylase enzymes? (Pyruvate carboxylase)

Answer 20

Biotin!

Pyruvate carboxylase
Acetyl CoA carboxylase
Propionyl CoA carboxylase

Question 21

Rate limiting step for gluconeogenesis?

Answer 21

F1,6BP -> F6P

Fructose 1,6 bisphosphatase

Question 22

What enzyme is present only in liver and kidneys, hence limiting gluconeogenesis in these organs?

Answer 22

Glucose 6-phosphatase

Question 23

High NADH levels due to chronic alcohol use favor which reactions?

Answer 23

Pyruvate to lactate
OAA to Malate
DHAP to glycerol 3 phosphate

Question 24

Glycosidic bond for branching?

Answer 24

a (1->6)

Question 25

Glycosidic bonds for elongation?

Answer 25

a (1->4)

Question 26

Where does glycogenesis occur?

Answer 26

Liver, muscle | Cytosol

Question 27

Core protein for glycogenesis?

Answer 27

Glycogenin

Question 28

Rate limiting step for glycogenesis?

Answer 28

Elongation of glycogen | Glycogen synthase

Question 29

Glycogen stores last for how long?

Answer 29

12-18 hours

Question 30

Rate limiting step for glycogenolysis?

Answer 30

``` Glycogen phosphorylase Requires pyridoxal phosphate Breaking a(1->4) bonds ```

Question 31

Type I glycogen storage disease

Answer 31

Von Gierke's Glucose 6-phosphatase Glycogen in liver and kidneys, hypogly, lactic acidosis, kerosine

Question 32

Glycogen storage disease that causes accumulation of glycogen in lysosomes, cardiomegaly, and heart failure?

Answer 32

Type II Pompe's disease Acid maltase deficiency

Question 33

Deficiency in debranching enzyme that causes mild hypoglycemia?

Answer 33

Type III | Cori's disease

Question 34

Glycogen storage disease that causes severe form of type I (early death from heart and liver failure). Deficiency in branching enzyme.

Answer 34

Type IV | Andersen's disease

Question 35

Problem with skeletal muscle glycogen phosphorylase causing muscle cramps and myoglobinuria but no lactic acidosis

Answer 35

Type V | McArdle's disease

Question 36

Type VI or Her's disease is a deficiency in what is enzyme?

Answer 36

Hepatic glycogen phosphorylase Causes glycogen in liver cells and hypoglycemia

Question 37

Deficiency in phosphofructokinase causing manifestations similar to type V glycogen storage disease but with hemolytic anemia

Answer 37

Type VII | Tarui's disease

Question 38

Type VIII glycogen storage disease is a deficiency in what enzyme?

Answer 38

Hepatic phosphorylase kinase | Presents like her's disease (glycogen in liver cells, hypogly)

Question 39

Autosomal recessive disease that causes cataracts + hepatosplenomegaly + mental retardation

Answer 39

Classic galactosemia Deficiency in galactose 1-P uridyltransferase Accumulation of galactitol

Question 40

Differentiate aldolase A and B

Answer 40

Aldolase A: glycolysis F1,6BP to DHAP + glycerol 3-P Aldolase B: fructose metabolism F1P -> DHAP + glyceraldehyde

Question 41

Deficienct enzyme in essential fructose is

Answer 41

Fructokinase Benign and asymptomatic

Question 42

Deficiency in aldolase B causes?

Answer 42

Fructose intolerance Autosomal recessive Sx: hypogly, jaundice, cirrhosis, vomiting

Question 43

Enzyme that converts glucose to sorbitol?

Answer 43

Aldose reductase

Question 44

Sorbitol dehydrogenase is found only in?

Answer 44

Seminal vesicles | Converts sorbitol to fructose

Question 45

Glycolysis: where?

Answer 45

Cytoplasm of all cells

Question 46

Main products of pentose phosphate pathway?

Answer 46

NADPH Ribose 5 phosphate Glyceraldehyde 3 phosphate Fructose 6 phosphate

Question 47

Rate limiting step in PPP?

Answer 47

Glucose 6 phosphate dehydrogenase | G6P -> 6-phosphogluconate

Question 48

Enzymes for phase 2 of PPP? What vitamin is required?

Answer 48

Transketolases | B1- thiamine

Question 49

Explain the problem in G6PD deficiency

Answer 49

Lack of NADPH inhibits action of glutathione reductase. Glutathione peroxidase cannot break down H2O2 Accumulation of free radicals and peroxides Hemolytic anemia triggered by oxidative stress

Question 50

Chronic granulomatous disease is a deficiency in what enzyme?

Answer 50

NADPH Oxidase No superoxides formed for respiratory burst Severe, persistent and chronic pyogenic infections with catalase + bacteria