Medical Biochemistry Past Test Paper

The peptide bond in proteins is

• Planar, but rotates to three preferred dihedral angles

• Non planar, but rotates to three preferred dihedral angles

• Non-planar, and fixed in a trans conformation

• Planar, and usually found in a trans conformation

Control of urea cycle involves the enzyme

• Carbamoyl phosphate synthetase

• Ornithine transcarbamoylase

• Arginino-succinase

• Arginase

At neutral pH a mixture of amino acids in solution would be predominantly

• Dipolar

• Nonpolar molecules

• Positive and monovalent

• Hydrophobic

Which of the following forces is the most favourable for protein folding?

• Conformational entropy

• Hydrophobic interactions

• Van Der Waals interactions

• Hydrogen bonds

Calculate the pH of a mixture of 0.3M acetic acid and 0.2M sodium acetate. The pKa of acetic acid is 4.76

• 5.1

• 4.1

• 6.1

• 4.9

An allosteric activator

• Increases the binding affinity

• Decreases the binding affinity

• Increases the Km number

• Binds the enzyme at the active site

A compound serving a link between citric acid cycle and urea cycle is

• Malate

• Succinate

• Fumarate

• Citrate

Nonessential amino acids

• Are not components of tissue proteins

• May be synthesised in the body from essential amino acids

• Have no role in the metabolism

• May be synthesised in the body even in diseased states

Fatty acids can be transported into and out of the cell plasma membrane by

• Active transport

• Diffusion

• Facilitated transport

• Osmosis

The two amino acids having R groups with a negative net charge at pH 7.4 are

• Aspartate and glutamate

• Arginine and histidine

• Cysteine and methionine

• Proline and Valine