Biochem

Question 1

All amino acids undergo transamination except

Answer 1

Lysine
Hydroxyproline
Proline
Threonine

Question 2

Coenzyme for transaminases

Answer 2

B6

Question 3

Coenzyme for transketolases

2nd phase of PPP

Answer 3

B1

Question 4

Substrates of urea cycle

Answer 4

CO2
Aspartate
NH3

Question 5

Rate-limiting step of urea cycle

Answer 5

CPS 1

Question 6

Reactions occuring both in the mitochondria and cytosol

Answer 6

Heme synthesis
Urea cycle
Gluconeogenesis

Question 7

How many moles of ATP are needed in the synthesis of urea?

Answer 7

3 moles of ATP

4 high-energy bonds

Question 8

Most common enzyme defect in urea cycle

Answer 8

Ornithine transcarbomylase deficiency

Question 9

Most severe enzymatic defect in urea cycle

Answer 9

CPS I deficiency

Question 10

phenylketonuria results from deficiency of what enzyme/coenzyme

Answer 10

phenylalanine hydroxylase

tetrahydrobiopterin

Question 11

coenzyme for branched chain AA dehydrogenase

Answer 11

B1

Question 12

coenzyme for pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase

Answer 12

B1

Question 13

enzymes of urea cycle

Answer 13

mitochondria:
CPS I
ornithine transcarbomylase

cytoplasm:
arginosuccinate synthetase
arginosuccinate lyase
arginase

Question 14

where does HMP shunt occurs

Answer 14

in the cytosol

RBCs and tissues that produce lipids (liver, adipose, adrenals, thyroid, testes, lactating mammaries)

Question 15

key enzyme of the 1st phase of HMP shunt

Answer 15

G6PD

Question 16

which phase of the HMP shunt yields 2 NADPH

Answer 16

Phase 1

Question 17

which phase of the HMP shunt is oxidative and irreversible

Answer 17

first phase

Question 18

condition characterized by kinky hair and growth retardation due to deficiency of copper required by lysyl oxidase

Answer 18

Menkes disease

Question 19

thymidilate synthase is inhibited by which drug

Answer 19

5-FU

Question 20

dihydrofolate reductase and dihydropteroate synthetase are inhibited by which drug/s

Answer 20

TMP-SMX

Question 21

IMP dehydrogenase is inhibited by which drug

Answer 21

Mycophenolate

Question 22

RNA primer of the leading strand is synthesized by

Answer 22

RNA polymerase

Question 23

RNA primer of the lagging strand is synthesized by

Answer 23

RNA primase

Question 24

amino acid necessary for the binding of O2 to heme

Answer 24

histidine

Question 25

CO2 is principally transported in the blood as

Answer 25

bicarbonate

Question 26

most abundant protein in the body

Answer 26

collagen

Question 27

what promotes hydroxylation of proline and lysine residues in collagen

Answer 27

Vitamin C

Question 28

coenzyme that is inactivated when bound to arsenic

Answer 28

lipoic acid

Question 29

major anaplerotic reaction that replenishes oxaloacetate

Answer 29

pyruvate carboxylase

Question 30

rate-limiting enzyme of glycolysis

Answer 30

PFK-1

Question 31

pancreatic enzymes for protein digestion

Answer 31

``` pancreTECC: Trypsin Elastase Chymotrypsin Carboxypeptidase ```

Question 32

what amino acid becomes essential in methionine deficiency

Answer 32

cysteine

Question 33

amino acid that links urea cycle to citric acid cycle

Answer 33

fumarate

Question 34

positive allosteric effector of CPS I

Answer 34

N-acetylglutamate

Question 35

amino acids that are converted to pyruvate

Answer 35

``` GlAyColySis Glycine Alanine Cysteine Serine ```

Question 36

thyroxine and melanin are precursors of

Answer 36

tyrosine

Question 37

tryptophan is the precursor of (3)

Answer 37

niacin serotonin melatonin

Question 38

(3) precursors of creatinine

Answer 38

SAM (methionine) Glycine Arginine

Question 39

Glutathione is synthesized from (3)

Answer 39

Glutamate Cysteine Glycine

Question 40

Coenzyme of acetylcoa carboxylase (lipogenesis)

Answer 40

biotin

Question 41

key enzyme in glyceroneogenesis

Answer 41

PEP carboxykinase

Question 42

net ATP yield in beta oxidation of palmitic acid

Answer 42

106 (new harper) | 129 (old harper)

Question 43

rate-limiting step of ketogenesis

Answer 43

HMG CoA synthase

Question 44

rate-limiting step of bile acid synthesis

Answer 44

7a hydroxylation

Question 45

Lipids that are absolutely essential in the diet

Answer 45

Linoleic acid | Arachidonic acid

Question 46

source of atoms common to both purine and pyrimidine rings

Answer 46

aspartate