P3 BIOCHEMISTRY UREA CYCLE

Question 1

Ammonia chemical characteristics

Answer 1

highly water soluble
colorless
irritant gas , pungent odor

Question 2

Ammonia reacts with water forming

Answer 2

strong alkaline solution + ammonium hydroxide

Question 3

sources of blood ammonia

Answer 3

Protein catabolism
Skeletal muscles
Intestinal bacteria

Question 4

Protein catabolism is done by

Answer 4

liver

Question 5

normal blood ammonia levels

Answer 5

10-50 micro mol/ L

Question 6

Increased ammonia levels can indicates

Answer 6

severe liver defect

Question 7

Ammonia levels can arise due to

Answer 7

Significant collateral circulation
Parenchymal cell dysfunction

Question 8

major disposal form of ammonia

Answer 8

urea

Question 9

site of urea cycle

Answer 9

Mitochondrial matrix
cytosol

Question 10

how many ATP molecules are utilised during urea cycle

Answer 10

3 ATP compound

Question 11

the enzyme that breaks down glutamate into ammonia is

Answer 11

Glutamate Dehydrogenase

Question 12

Enzyme present in the liver that helps ls in the release of ammonia

Answer 12

Glutaminase

Question 13

Carrier of ammonia from muscle to liver

Answer 13

Alanine

Question 14

once ammonia is in the mitochondria of hepatocyte , it will combine with bicarbonate forming

Answer 14

Carbamoyl phosphate

Question 15

Enzyme converting ammonia + HCO3 to carbamoyl phosphate

Answer 15

carbamyl phosphate synthase 1

Question 16

ATP molecules utilised by CPS1

Answer 16

2 ATP molecules

Question 17

carbamoyl phosphate combined with what forming Citrulline

Answer 17

Ornithine

Question 18

Enzyme that converts carbamoyl phosphate to citrulline

Answer 18

ornithine transcarbamylase OTC

Question 19

Exiting into cytosol , citrulline combines with aspartate forming

Answer 19

argininosuccinate

Question 20

formation of argininosuccinate is done by which enzyme

Answer 20

argininosuccinate synthetase

Question 21

how many ATP molecules are utilised by AS enzyme

Answer 21

1

Question 22

argininosuccinate breaks down into

Answer 22

fumarate & arginine

Question 23

Arginine with enzyme ariginase forms

Answer 23

urea

Question 24

role of ammonia related to proteins

Answer 24

Anabolism & catabolism of amino acids

Question 25

other roles of ammonia

Answer 25

• maintain acid base balance
• conserve cations

Question 26

levels of ammonia in metabolic acidosis

Answer 26

Increased

Question 27

levels of ammonia in metabolic alkalosis

Answer 27

Decreased

Question 28

Ammonia toxicity is due to increase in what enzymes

Answer 28

glutamate dehydrogenase
Glutamine synthase

Question 29

Hyperactivity of these enzymes results in

Answer 29

Decreased alpha-keto-glutarate

Question 30

most sensitive organ to ammonia toxicity

Answer 30

brain

Question 31

Ammonia levels in hepatic failure

Answer 31

high

Question 32

Ammonia & glutamine levels in inherited disorders of urea cycle enzymes

Answer 32

high

Question 33

Substances that can be used to promote waste nitrogen excretion

Answer 33

• sodium benzoate
• sodium phenylacetate

Question 34

Sodium benzoate conjugates with

Answer 34

Glycine

Question 35

sodium phenylacetate conjugates with

Answer 35

glutamine

Question 36

Sodium benzoate + glycine forms

Answer 36

hippuric acid

Question 37

Sodium phenylacetate + glutamine forms

Answer 37

phenylacetylglutamine