A-Level Biology AQA 7402

1.4.1: General properties of proteins

#1.4.1.1

Amino acids are the monomers from which proteins are made. The general structure of an amino acid as:

mtaimg/images/sections/645/645-1-1.png/mtaimg

where NH2 represents an amine group, COOH represents a carboxyl group and R represents a side chain. The twenty amino acids that are common in all organisms differ only in their side group.

#1.4.1.2

A condensation reaction between two amino acids forms a peptide bond.

  • Dipeptides are formed by the condensation of two amino acids.
  • Polypeptides are formed by the condensation of many amino acids.
#1.4.1.3

A functional protein may contain one or more polypeptides.

#1.4.1.4

The role of hydrogen bonds, ionic bonds and disulfide bridges in the structure of proteins.

#1.4.1.5

Proteins have a variety of functions within all living organisms. The relationship between primary, secondary, tertiary and quaternary structure, and protein function.

#1.4.1.6

The biuret test for proteins.

#1.4.1.7

Students should be able to relate the structure of proteins to properties of proteins named throughout the specification.

1.3
Lipids
1.4.2
Many proteins are enzymes