Nitrogen Metabolism

Question 1

what is the final step to nitrogen removal?

Answer 1

oxidative deamination (glutamate dehydrogenase will oxidatively deaminate glutamate to form ammonia

Question 2

how are amino acids converted to glutamate?

Answer 2

via transamination reactions

Question 3

what do transamination reactions require?

Answer 3

PLP

Question 4

what is the role of CPSaseI?

Answer 4

it uses the free ammonium to form carbamoyl phosphate which then feeds into the urea cycle

Question 5

Hartnup disease affects membrane transport of what amino acids?

Answer 5

neutral amino acids

Question 6

Cystinuria affects the membrane transport of what amino acids?

Answer 6

dibasic amino acids

Question 7

as filtrate passes through the PCT, transport proteins from what gene superfamily mediate the reuptake of amino acids and glucose?

Answer 7

from the SLC (solute carrier) gene superfamily

Question 8

what specific amino acid is not reabsorbed in Hartnup’s disease?

Answer 8

tryptophan

Question 9

what specific amino acids are not absorbed in Cystinuria?

Answer 9

COAL (cystine, ornithine, arginine, and lysine

Question 10

what is tryptophan a precursor of?

Answer 10

serotonin, melatonin, and niacin

Question 11

what is niacin a really important precursor for?

Answer 11

formation of NAD

Question 12

what is the inheritance like of cystinuria?

Answer 12

it is autosomal recessive- males

Question 13

what does cystinuria result in?

Answer 13

the formation of cystine renal calculi

Question 14

What causes PKU?

Answer 14

a defect in the reaction that converts Phe–> Tyr (defect in phenylalanine hydroxylase

Question 15

what is secondary (non-classical PKU)?

Answer 15

a dihydrobiopterin reductase deficiency

Question 16

what are the toxic substances associated with PKU?

Answer 16

phenyllactate and phenylacetate

Question 17

what causes the musty odor associated with PKU?

Answer 17

phenyllactate

Question 18

what is the essential cofactor of phenylalanine hydroxylase?

Answer 18

tetrahydrobiopterin

Question 19

what is used in treatment of secondary PKU?

Answer 19

synthetic THB

Question 20

what causes transient tyrosinemias in newborns?

Answer 20

delayed expression of 4-HPPD

Question 21

what causes tyrosinemia type 1?

Answer 21

defect in fumarylacetoacetate hydrolase

Question 22

what is the go to treatment for tyrosinemia type 1?

Answer 22

nitisinone

Question 23

what is tyrosinemia type 2 caused by?

Answer 23

defective tyrosine aminotransferase

Question 24

clinical signs of tyrosemia type 2?

Answer 24

occular manifestations including excessive tearing, redness, pain, and photophobia

Question 25

what causes tyrosinemia type 3?

Answer 25

defective 4-HPPD

Question 26

what causes alkaptonuria?

Answer 26

defective homogentisate oxidase

Question 27

what accumulates in alkaptonuria?

Answer 27

homogentisic acid

Question 28

what is the characteristic triad of alkaptonuria?

Answer 28

homogentisic aciduria, dark sclera, and arthritis

Question 29

what enzyme is responsible for converting glutamate into alpha ketoglutarate?

Answer 29

glutamate dehydrogenase

Question 30

what enzyme is responsible for converting amino acids into alpha keto aicd?

Answer 30

amino transferases

Question 31

what enzyme is responsible for converting glutamate into glutamine?

Answer 31

glutamine synthase

Question 32

what enzyme is responsible for converting glutamine into glutamate?

Answer 32

glutaminase