3.5 gluconeogenesis, nitrogen metabolism and amino acid balance

Question 1

what are the 4 enzymes involved in gluconeogenesis of pyruvate into blood glucose

Answer 1

pyruvate carboxylase
PEP carboxylase
fructose 1,6 bisphosphatase
glucose 6 phosphatase

Question 2

what does pyruvate carboxylase do

Answer 2

Adding carbon to pyruvate to form oxaloacetate

Question 3

what does PEP carboxylase do

Answer 3

Converting oxaloacetate to PEP

Question 4

what does fructose 1,6 bisphosphatase do

Answer 4

converting fructose 1,6 bisphosphate into fructose 6 phosphate

Question 5

what does glucose 6 phosphatase do

Answer 5

converting glucose - 6 phosphate into blood glucose

Question 6

define gluconeogenesis

Answer 6

making glucose from non carbohydrate metabolic intermediates

Question 7

what are some non carbohydrate metabolic intermediates during fasting

Answer 7

amino acids, glycerol

Question 8

what are some non carbohydrate metabolic intermediates during intense exercise

Answer 8

lactate

Question 9

what are some non carbohydrate metabolic intermediates when converting absorbed nutrients into glucose

Answer 9

○ Converting absorbed nutrients into glucose
Propionate (ruminants)

Question 10

An animal is in nitrogen balance when:

Answer 10

N intake = N excretion

Question 11

An animal is in positive nitrogen balance when and why

Answer 11

• An animal is in positive nitrogen balance when:

N intake > N excretion (e.g. Growth and pregnancy)

Question 12

An animal is in negative nitrogen balance when and why

Answer 12

• An animal is in negative nitrogen balance when:

N intake < N excretion (e.g. starvation - not enough proteins)

Question 13

source of amino acid in the pool

Answer 13

• endogenous proteins
• dietary proteins

Question 14

how is the amino acid used

Answer 14

NH3 is removed to form alpha-keto acid which is then used for synthesis (anabolic) or energy production (catabolic)

Question 15

what else does amin acids form

Answer 15

• It also forms non-protein nitrogenous compounds

e.g. neurotransmitters and nucleotides

Question 16

how is ammonia excreted in ammoniotelic, uricotelic, and ureotelic animals

Answer 16

Ammoniotelic organisms (e.g., fish) excrete ammonia directly.

Uricotelic organisms (e.g., birds, reptiles) excrete uric acid, which contains four nitrogen atoms.

Ureotelic organisms (e.g., mammals) convert ammonia to urea, which is excreted in urine.

Question 17

what happens in transamination

Answer 17

The amino group and the carboxyl group switches

amino acid and alpha keto-glutarate is converted into glutamate and alpha-keto acid

Question 18

how do glutamate convert into glutamine and why

Answer 18

○ Glutamate is converted into glutamine by adding NH4+ (amino acid - solid form - easier transport)

it needs to be transported to the liver

Question 19

what happens to glutamine when it is transported to the liver

Answer 19

In the liver, glutamine is converted back into glutamate by a different enzyme reaction.

The NH4+ released is used for urea synthesis

Question 20

what happens to ammonia when it is released in the liver

Answer 20

it combines with CO2 and enters the urea cycle

Question 21

what happens when levels of ammonia in blood rises

Answer 21

ammonia intoxication

Question 22

what will the build up of ammonia causes (2)

Answer 22

1. The build up of ammonia will reverse glutamate dehydrogenase reaction

• this uses up α-ketoglutarate (intermediate in citric acid cycle)

2, It also promotes conversion of glutamate, neurotransmitter, to glutamine

Question 23

clinical signs of ammonia intoxication (4)

Answer 23

1. intolerance to high protein food
2. vomiting
3. coma
4. death

Question 24

causes of ammonia intoxification

Answer 24

1. genetic defect
2. liver damage or diseases

Question 25

treatments to improve ammonia intoxification

Answer 25

1. low protein diet food
2. eat small amount of protein at regular intervals