nitrogen

Question 1

where does our nitrogen come from?

Answer 1

amino acids and nucleotides

Question 2

what is the metabolism of dietary proteins in the stomach?

Answer 2

Pepsin cuts protein into peptides

Question 3

what is the metabolism of dietary proteins in the small intestine?

Answer 3

trypsin and Chymotrypsin cut proteins and large peptides into smaller peptides

• Aminopeptidase and Carboxypeptidases A and B degrade peptides into amino acids

Question 4

what happens to all proteins?

Answer 4

All proteins are turned over and hence there is a need to replace them.

Some are highly stable lasting for days or weeks, while others may last for minutes.

Question 5

what is the product of the degradation of cellular proteins?

Answer 5

amino acids

Question 6

what type of cellular proteins get degraded?

Answer 6

Misfolded proteins

Foreign proteins

Unwanted proteins

Question 7

describe the formation of urea

Answer 7

Amino acids come from:

• Ingested protein
• Alanine from muscle
• Glutamine from muscle and other tissues

Amino Acid metabolism produces ammonia NH4+

Ammonia goes in the Urea Cycle → Urea/Uric Acid out

Question 8

what is phenylketonuria?

Answer 8

it’s when there is an absence/deficiency in Phenylalanine hydroxylase so the amino acid Phenylalanine can’t be converted to Tyrosine.

If not treated Phenylalanine → Phenylketones accumulate and can cause irreversible brain damage.

Treated by supplementing low protein diet with Tyrosine.

Question 8

what is the most common urea cycle disorder?

Answer 8

ornithine transcarbamoylase (OTC)

Question 9

describe hyperammonaemia:

Answer 9

elevated blood ammonia levels - medical emergency

highly toxic

They are typically present in the neonatal period.