Nitrogen

Question 1

What is meant by the term ‘glucogenic amino acid’?

Answer 1

These are amino acids which are metabolised to pyruvate or citric acid cycle intermediates, and end up as glucose.

Question 2

What is meant by the term ‘ketogenic amino acid’?

Answer 2

These are amino acids which provide acetyl CoA or acetoacetate carbon atoms.

Question 3

What are the four most common amino acids in human cells?

Answer 3

Alanine, glutamate, glutamine and asparate

Question 4

What is meant by transamination?

Answer 4

The transfer of amino groups between different molecules to conserve nitrogen.

Question 5

What cofactor do all aminotransferase reactions rely on?

Answer 5

Pyridoxal phosphate cofactor

Question 6

Under what three circumstances does amino acid catabolism occur?

Answer 6

1. When left-over amino acids from normal protein turnover are present
2. When dietary amino acids which exceed body’s protein synthesis needs are present
3. In times of starvation when carbohydrates and lipids are in short supply.

Question 7

What are the five main enzymes used in the hydrolysis of proteins?

Answer 7

Pepsin, trypsin, chymotrypsin, aminopeptidase, carboxypeptidase

Question 8

What is the role of pepsin in protein hydrolysis?

Answer 8

Cuts proteins into peptides in the stomach

Question 9

What is the role of trypsin in protein hydrolysis?

Answer 9

Cuts proteins and larger peptides into smaller peptides in the small intestine

Question 10

What is the role of chymotrypsin in protein hydrolysis?

Answer 10

Cuts proteins and larger peptides into smaller peptides in the small intestine

Question 11

What is the role of aminopeptidase in protein hydrolysis?

Answer 11

Degrade peptides into amino acids in the small intestine

Question 12

What is the role of carboxypeptidase in protein hydrolysis?

Answer 12

Degrade peptides into amino acids in the small intestine