Lecture 9 - Urea Cycle

Question 1

What occurs in the first reaction of the urea cycle?

Answer 1

NH3 and CO2 are converted to carbamoyl phosphate

Question 2

Cofactor for reaction 1

Answer 2

2 ATP -> 2 ADP + Pi

Question 3

Reaction 2

Answer 3

Omithine and carbamoyl phosphate are converted to citrulline

Question 4

Enzyme for reaction 1

Answer 4

Carbamoyl phosphate synthetase

Question 5

Enzyme for reaction 2

Answer 5

Ornithine transcarbamolyase

Question 6

Cofactor for reaction 2

Answer 6

Pi out

Question 7

Reaction 3

Answer 7

Citrulline and asparate converted to argininosuccinate

Question 8

Enzyme for reaction 3

Answer 8

Argininosuccinate synthetase

Question 9

Cofactor for reaction 3

Answer 9

ATP -> AMP + PPi

Question 10

Reaction 4

Answer 10

Argininosuccinate is converted to arginine and fumarate, which is then converted to aspartate

Question 11

Enzyme for reaction 4

Answer 11

Argininosuccinate lyase

Question 12

Cofactor for reaction 4

Answer 12

None

Question 13

Reaction 5

Answer 13

Arginine is converted to ornithine and urea

Question 14

Enzyme for reaction 5

Answer 14

Arginase

Question 15

Cofactor for reaction 5

Answer 15

None

Question 16

How much ATP is used/produced in the urea cycle?

Answer 16

4 ATP is used; 2 for carbamoyl phosphate, and 2 for argininosuccinate synthetase