catabolism of carbon skeletons of amino acids

Question 1

First catabolic reaction of all common acids
A. Transamination
B. Transdeamination
C. Oxidation
D. Transferase

Answer 1

A.
Except for proline, hydroxyproline, threonine or lysine.
The hydrocarbon that remains is degraded to amphibolic intermediates

Question 2

The nitrogen of thid imino acid is retained throughout its oxidation and it does not participate in transamination
A. Histidine
B. Proline
C. Ornithine
D. Arginine

Answer 2

B

Question 3

Metabolic block at proline dehydrogenase
A.type I hyperprolinemia
B.type 2 hyperprolinemia

Answer 3

A

Question 4

Metabolic block at glutamate-y-semialdehyde dehydrogenase
A.type I hyperprolinemia
B.type 2 hyperprolinemia

Answer 4

B

Question 5

Condition caused by impaired transfer of formimino group

Answer 5

Folic acid deficiency
(Formimimono group transfer to tetrahydrofolate forms glutamate then a-ketoglutarate)
Figlu is excreted-can be detected

Question 6

Enzymes for glycine cleavage system except
A. Glycine dehydrogenas
B. Aminomethyltransferase
C. Dihydrolipoamide dehydrogenase
D. Hydroxyproline dehydrogenase

Answer 6

D. For catabolism of hydroxyproline

Glycine has H-protein attached to dihydrolipoyl moiety

Question 7

Interconversion of serine and glycine is catalyzed by

Answer 7

Hydroxymethyltransferase

Question 8

Results from deficiency in the reaction catalyzed by cystathionine B-synthase

Answer 8

Vit. B6-responsive/unresponsive homocystinurias

Question 9

Cleaves threonine to acetaldehyde and glycine
A. Threonine cyclase
B. Threonine lyase
C. Threonine aldolase
D. Threonine synthase

Answer 9

C.

Question 10

What is formed during the aldol-type cleavage in hydroxyproline catabolism

Answer 10

Glyoxylate and pyruvate

Question 11

Additional amino acids that form Acetyl-CoA, except
A.tyrosine
B.phenylaalanine
C.lysine
D.tryptophan
E.methionine
F. None of the above

Answer 11

F :))

Question 12

Defect in tyrosine aminotransferase

Answer 12

Type II tyrosinemia (Richner-Hanhart syndrome

Question 13

What enzyme is impaired in alakotonuria?
A. Homogentisate oxidase
B. P-hydroxyphenylpyruvate hydroxylase
C. Fumarylacetoacetate hydrolase
D.phenylalanine hydroxylase

Answer 13

A
B. Neonatal tyrosinemia
C.type 1 tyrosinemia
D.PKU Type 1, detected 3-4 days postpartum, false postive in premature infants

Question 14

The first 6 reactions of L-lysine cataolism in human liver forms
A. Saccharopine
B. L-a-amimoadipate
C. A-ketoadipate
D. Crotonyl-CoA
E. Glutaryl-CoA

Answer 14

D.

A-1st
B-3rd
C-4th
D. 5th
Subsequent reactions are those of fatty acid catanolism

Question 15

Tryptophan is degraded to amohibolic intermediates via what pathway?

Answer 15

Kynurenine-anthranilate pathway

Question 16

Its excretion in response to a tryptophan load is diagnostic for vit. B6 deficiency
A. Trytophan
B. Tyrosine
C. Xanthurenate

Answer 16

C

Question 17

Methionine reacting with ATP forms

Answer 17

S-adenosylmethionine “active methionine”

Reaction forms propionul CoA them succinyl CoA

Question 18

Disease as a result of defect in a-keto acid decarboxylase complex

Answer 18

Maple syrup disease (branched-chain ketonuria