Proteins & Nitrogen Metabolism

Question 1

major inhibitory NT in spinal cord, released

Answer 1

glycine

Question 2

aa with the largest side chain

Answer 2

Trp

Question 3

site for N-linked glycosylation of proteins

Answer 3

Asparagine

Question 4

precursor for GABA and glutathione

Answer 4

Glutamate

Question 5

aa also used in dx of folic acid deficiency

Answer 5

histidine

FIGLU excretion test

Question 6

precursor of carinitine

Answer 6

lysine

Question 7

21st amino acid

Answer 7

selenocysteine

Question 8

configuration of Hgb with high O2 affinity

Answer 8

R (relaxed) form

Question 9

O2 dissociation curve of myoglobin vs Hgb

Answer 9

myoglobin: hyperbolic
Hgb: sigmoidal

Question 10

stabilizes the T structure of Hgb by forming additional salt bridges that must be broken prior to conversion to R state

Answer 10

2,3 BPG

Question 11

Hgb cherry pink in color

Tx?

Answer 11

carboxyHgb

Tx: 100% O2

Question 12

chocolate cyanosis

Tx?

Answer 12

Methemoglobin

methylene blue

Question 13

MC mutation in hereditary spherocytosis

Answer 13

ankyrin

Question 14

Dx of hereditary spherocytosis

Answer 14

osmotic fragility test

Question 15

mutation in sickle cell disease

Answer 15

E6V
glutamic E → val
polar to nonpolar

Question 16

mutation in Hgb C disease

Answer 16

single aa sub at 6th position of B globin chain

lys → glutamate

Question 17

most abundant protein in the body

Answer 17

collagen

Question 18

dystrophic form due to mutations in

Answer 18

type VII collagen

which anchors the basal lamina to collagen fibrils in the dermis

Question 19

role of Cu in Menke dse

Answer 19

lysyl oxidase for formation of covalent cross links that strengthen collagen fibers requires Cu

Question 20

Marfan syndrome is mutation in

Answer 20

fibrillin gene

Question 21

tall, thin, dolichostenomelia, arachnodactyly, aortic dilatation and ectopia lentis

Answer 21

Marfan syndrome

Question 22

RLS of urea cycle

Answer 22

NH3 + CO2 → carbamoyl phosphate

CPS I
allosteric activator: N-acetylglutamate

Question 23

MC enzyme deficiency in urea cycle

Answer 23

ornithine transcarbomylase

Question 24

most severe enzyme deficiency in urea cycle

Answer 24

CPS-1 def

Question 25

creatine, polyamines, NO from

Answer 25

arginine

Question 26

MC deficiency in homocystinuria

Answer 26

cystathionine B synthase

Question 27

methylmalonyl coA mutase involves the matabolism of amino acids convered to propionyl coA

Answer 27

isoleucine, valine, threonine, methionine

Question 28

2 enzymes inhibited by lead in heme synthesis

Answer 28

ALA dehydratase

Ferrochelatase

Question 29

Enzyme def in porphyria cutaneous tarda

Answer 29

uroporphyrinogen decarboxylase

Question 30

Enzyme def in acute intermittent porphyria

Answer 30

hydroxymethylbilane synthase

UP 1 synthase