Amino Acid Metabolism

Question 1

What are the X10 essential amino acids?

Answer 1

Valine (very)
Methionine (many)
Histidine (hairy)
Lysine (little)
Phenylalanine (pigs)
Leucine (live)
Isoleucine (in)
Threonine (the)
Tryptophan (torrid)
Arginine (argentine)

Question 2

What is positive nitrogen balance and when does it occur?

Answer 2

Nitrogen intake > nitrogen oxide excretion

(Protien synthesis > rate of brewkdown)

Occurs in:

1) normal child growth
2) convalescence after serious illness
3) pregnancy

Question 3

What is deamination?

Which is the only amino acid that can undergo oxidative deamination?

Which enzyme is responsible for this?

Answer 3

The removal of an amine group.

Glutamate.

Enzyme = glutamate dehydrogenase.

Question 4

What does the breakdown of an amino acid end up as?

Answer 4

An amine group (NH2)

An oxo/keto acid group (CH3-(C=O)-COOH)

Question 5

What is transamination?

What is it used for?

Answer 5

The moving of an amine group from one amino acid to a different keto acid, making it an amino acid and turning the original A.A. into an oxo/keto acid.

Transamination is a method of synthesising non-essential amino acids.

Question 6

What happens to the oxo/keto acids in amino acid metabolism?

Answer 6

When an amine group is removed:

X13 = amino acids form a molecule that is part of the TCA cycle or pyruvate (glucogenic amino acids as their carbon skeleton can by converted back to glucose via gluconeogenesis).

Leucine & lysine can only be degraded to acetyl CoA (ketogenic amino acids).

Question 7

Can acetyl CoA be turned back into pyruvate?

Answer 7

No this is an irreversible reaction.

Question 8

What are the X2 fates of acetyl CoA formed by ketogenic amino acids from amino acid catabolism?

Answer 8

1) Enters the TCA cycle = turned into CO2 & H2O

2) can synthesise fats

Question 9

What is the fate of the amino group from amino acid catabolism via deamination/transamination?

Where does this occur?

What molecule helps export amino groups in the blood? How many can it transport at once? Why is this important?

Answer 9

Turns to ammonia and is excreted in the urine as urea.

In the liver.

Glutamine = can carry X2 amine groups at once, forming glutamine. This is important as it is a safe carrier of ammonia, as ammonia is toxic to the brain.

Question 10

What are the X2 fates of TCA cycle components formed by glucogenic amino acids from amino acid catabolism?

Answer 10

1) Enters the TCA cycle = turned into CO2 & H2O

2) can be turned to glucose via gluconeogenesis