Amino acids

Question 1

Define isoelectric point

Answer 1

pH at which a molecule carries no electrical charge

Question 2

Peptide bonds have weak/strong resonance

Answer 2

strong

Question 3

Delocalisation stabilises peptides by 75-90kJmol, so peptides prefer to be in linear/planar conformation.

Answer 3

planar

Question 4

What is the amino acid sequence of Glutathione?

Answer 4

Glu - Cys - Gly

Question 5

Glutathione forms Hydrogen/disulphide bonds in the presence of oxidising agent. It acts as a natural antioxidant.

Answer 5

Disulphide

Question 6

Insulin is a hormone made in the ____, which makes ____

Answer 6

pancreas

glucose

Question 7

What method can be used to find the isoelectric point of a protein?

Answer 7

pH electrophoresis

Question 8

Amino acids are chiral except ____, and they all exist in the _____ form

Answer 8

Glycine

L-optical

Question 9

What is a zwitterion made of?

Answer 9

acid and base

Question 10

State the number of amino acid residues in oligopeptides, polypeptides, and proteins

Answer 10

oligopeptides - 2-10
polypeptides - 10-50
proteins -50-400

Question 11

List 2 purification methods used for peptides and proteins

Answer 11

• Polyamide gel electrophoresis (PAGE)

- Agarose - DNA/ large proteins/ enzyme complexes

Question 12

What shape of protein is produced after it is denatured by SDS

Answer 12

uniform rod shape