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Flashcards in urea cycle Deck (14)
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1

what is the first step of the urea cycle? where is it happening?

substrate, products? Importance?

mitochondial reaction

substrates: ammonia and co2 (or bicarbonate)

2 ATP

e: carbomoyl phosphate synthetase 1

product: carbomoyl phosphate

2

what is this? where does it go next?

carbamoyl phosphate

 

combines with ornithine to create citruline in the mitochondia

3

what are these and what do they create?

with which enzyme?

they were ornithine and carbamoyl phosphate

they create citruline (see below) with ornithine trasncarbamoylase

4

what are these and what do they create?

with which enzyme?

aspartate (asp) and citruline produce arginosuccinate (seen below) with ATP

Arginosuccinate synthetase

5

what are these and what do they create?

with which enzyme?

arginosuccinate and fumarate leaving

this produces arginine

enzyme: Arginosuccinate lyase

6

what is this and in the urea cycle, what does it produce via which enzyme?

arginine will meet the enzyme arginine lyase and forms ornithine and urea

7

when citruline is formed, where does it go?

it leaves the mitochondia through a citruline transporter and enters the cytosol for the remainder if the urea cycle

8

when ornithine is formed, where does it go to continue the urea cycle? how?

ornithine goes back into the mitochondia via ornithine transporter

9

what is trypsin? where does it cut?

trypsin is an endopeptide that cuts the peptide bond after (on the c term side) arginine and lysine

10

what is chymotrypsin? where does it cut?

trypsin is an endopeptide that cuts the peptide bond after (on the c term side) of aromatic amino acids

tyrosine, phenylalanine, tryptophan

11

how many ATP are needed for one urea cycle?

4 atp per cycle

12

what is the activator of carbamoyl phosphate synthetase 1?

N acetyl glutamate

13

n acetyl glutamate is made how? what activates this reaction?

glutamate + acetyl-coa + atp

enzyme: n acetyl glutamate synthetase

arginine activates the production of n acetyl glutamate

14

what are the 3 ways the urea cycle can be regulated?

1: high protein diet causes 10-20x higher enzyme levels

2: N acetyl glutamate activates the 1st step (the rate determining step)

3: high ornithine or arginine causes increased urea cycle rate