Aromatic AA

Question 1

what enzyme converts phenylalanine to tyrosine

Answer 1

phenylalanine hydroxylase

Question 2

when phenylalanine undergoes rxn with phenylalanine hydroxylase what does it form?

Answer 2

tyrosine

Question 3

what are the hetogenic AA

Answer 3

leucine and lysine

Question 4

when phenylalanie builds up what happens

Answer 4

phenylalanine prevents the trnsport of tyrosine and trypophan into the brain

Question 5

what cofactor is necessary for phenylalanine hydroxylase

Answer 5

tetrahydrabiopterin

Question 6

the conversion of tyrosine to NE/E requires what

Answer 6

tetrahydrabiopterin

Question 7

a defect in phenylalanine hydroxylase

Answer 7

Phenylketonuria

Question 8

why is supplementing with a low phenylalanine diet is not ok becuase

Answer 8

tetrahydrobiopterin is required for the activity of enzymes involved in serotonin and catecholamine synthesis

Question 9

what does tyrosine make

Answer 9

NE/E, thyroxine and melanin

Question 10

what enzyme is involved in recycing the tetrahydrabiopterin?

Answer 10

dihydrobiopterin reductase which reacts dihydrabiopter with NADPH to make tetrahydrabiopterin

Question 11

why cant you treat people with PKU with low phenylalanine diet?

Answer 11

cause you need tetrahydrabiopterin to make catecholamines and seratonin

Question 12

tyrosine is also broken down (other than the NE, melanin and thyroxine) into

Answer 12

hydroxyphenylpyruvate

Question 13

the second step of thyroxine break down is the production of

Answer 13

homogentisate

Question 14

Homogentisate comes from

Answer 14

tyrosine

Question 15

homogentisate is broken down by

Answer 15

homogentisate dioxygenase

Question 16

when there is a defect in homogentisate dioxygenase what disease occurs

Answer 16

alcaptoneuria

Question 17

symptoms of alcaptoneuria?

Answer 17

the urine turns black

Question 18

what is the action of the homogentisate dehydrogenase enzyme

Answer 18

it opens the aromatic ring

Question 19

with ageing what do you get in alcaptoneuria?

Answer 19

osteoarthritis

Question 20

tyrosine is finally broken into

Answer 20

fumarate and acetoacetate

Question 21

elevated tyrosine will lead to

Answer 21

Tyrosinemia type II

Question 22

Tyosinemia type I

Answer 22

due to the accumulation of fumaryl acetoacetate which gets conerted to succinylacetate that inhibits DNA repair

Question 23

dymptoms of tyrosemia type I

Answer 23

liver failure, renal dyfunction, tumorigensis

Question 24

individuals with type I tyrosinemia smell like

Answer 24

cabbage

Question 25

treatment of Type I tyrosinemia

Answer 25

NTBC which inhibits an emzyme higher up the branch to induce type III which is less severe

Question 26

tryptophan can be broken down into

Answer 26

seratonin which breaks down into melatonin. Also kynurenine which breaks down into quinolinic acid, eventually forming niacin

Question 27

what rxn in the tryptophan pathway involves tetrahydrabiopterin

Answer 27

the conversion of tryptophan to seratonin

Question 28

what is made in the conversion of tryptophan to kyneuranine

Answer 28

formate, adding to the formic acid pool

Question 29

tryptophan hydroxylase makes? and requires what?

Answer 29

sertaonin and tetrahydrabiopterin

Question 30

niacin comes from

Answer 30

tryptophan

Question 31

Hartnups disease

Answer 31

defect in a neutral AA transporter, Tryptophan cannot be taken up, looks like pllegra since you can to make niacin.