urea cycle and fate of a-ketoacidosis

Question 1

ammonia in the liver is converted to what?

Answer 1

urea- urea cycle

Question 2

what are 2 unique abilities of the liver?

Answer 2

• the ability to turn ammonia into urea for excretion

- the ability to turn a-ketoacids into glucose

Question 3

what 2 amino acids transfer ammonia (NH3) to the liver?

Answer 3

glutamine

alanine- via glucose-alanine cycle

Question 4

what are the 2 entry points of nitrogen to the urea cycle?

Answer 4

GDH- glutamate dehydrogenase
*oxidative deamination
AST- aspartate aminotransferase
*forms aspartate which is a source of nitrogen

Question 5

which enzyme begins the urea cycle?

Answer 5

carbamyol phosphate

Question 6

what enzyme catalyzes arginine into ornithine and urea?

Answer 6

arginase

Question 7

what happens to the ornithine in the urea cycle?

Answer 7

it re-enters the cycle

Question 8

what happens to the urea?

Answer 8

it is transported in the blood to the kidneys to be excreted

Question 9

each urea molecule has how many nitrogens?

Answer 9

2

1- from free NH3
2- from aspartate

Question 10

what is the precursor for both nitrogens in a urea molecule?

Answer 10

glutamate

1. deaminated to produce free amino group
2. donates amino group to OAA to become aspartate

Question 11

50% of ATP production in the liver is from?

Answer 11

AA oxidation

Question 12

what are the 6 amino acids that skeletal muscle can oxidize?

Answer 12

LIV GAA
leucine 
isoleucine
valine 
glutamate
aspartate 
asparagine

Question 13

after a meal, muscle has a large uptake of?

Answer 13

BCAA and glutamate- more than 90% of muscle amino acid uptake

Question 14

the splanchnic area constantly releases?

Answer 14

glutamate- consumes glutamine, releases glutamate

Question 15

after a meal, muscles release of ____ more than doubles

Answer 15

glutamine

Question 16

what does muscle use BCAA for?

Answer 16

fuel

nitrogen to make glutamine for export

Question 17

when exercising, ATP turnover within skeletal muscle can increase how much?

Answer 17

100 fold

Question 18

during exercise, TCA intermediates increase about how much?

Answer 18

4-10 fold

Question 19

with exercise, the demand for ATP requires a much more active?

Answer 19

kreb’s cycle

Question 20

what does running glycolysis faster than krebs produce?

Answer 20

extra pyruvate to pick up amino groups from the amino acids being oxidized in muscle
-results in increased alanine

Question 21

during exercise, glutamate concentrations _______ and alanine concentrations ___________

Answer 21

decrease; increase

Question 22

what group of AA are released in amounts LESS than what is taken in?

Answer 22

BCAA, glutamate, aspartate, asparagine

Question 23

what group of AA are released in amounts MORE than what is taken in?

Answer 23

alanine, glutamine

Question 24

what are the 2 most abundantly released AA?

Answer 24

glutamine- 50%

alanine- 30%

Question 25

what 2 amino acids are ketogenic only?

Answer 25

leucine

lysine

Question 26

how do we turn AA into fat?

Answer 26

convert AA into a-ketoacid
convert a-ketoacid into acetyl-coA
make fatty acids