Protein Metabolism Session 5

What DOES NOT contribute to amino acid pool ?

• Degrading tissue proteins

• Making essential amino acids in the body

• Proteins from food

• Everything contributes

Which part of an amino acid provides a source of energy?

• The whole molecule

• The whole molecule EXCEPT the Hydroxyl group

• The whole molecule EXCEPT the amino group

• The amino group

Phenylalanine is convetred in Tyrosine by enzyme Phenylalanine Hydrolxylase by the process called

• Hydroxylation

• Methylation

• Oxidation

• Carboxylation

Answer explanation

The first step in the metabolism of phenylanine is its oxidation to tyrosine by the enzyme Ph H. This enzyme is defective in most cases of PKU. As a result of the deficiency, phenylalanine accumulates in tissues and blood and cause damge.

The total protein turnover in a healthy adult is:-

• 100-200 g/day

• 200-300 g/day

• 300-400 g/day

• 400-500 g/day

Answer explanation

Of this, 100-150 g are muscle proteins and digestive enzymes. Normally the rate of protein breakdown equals the rate of resynthesis.

What makes an amino acid non essential ?

• Not metabolized by the body

• Not needed to build proteins but can be burnt for energy

• Must be provided by the diet

• Can be synthesized by the body

Answer explanation

Total amino acids = 20 ,

Essential amino acids cannot be made by the body. As a result, they must come from food. There are 9 in number  and rest are non essential amino acids i.e 11