Protein Structure & Function (SQA National 5 Biology): Revision Note

Proteins are molecules made from individual units called amino acids

The sequence of amino acids bonded together forms the basic structure, which is is specific for each protein

• A single alteration in the sequence of amino acids can affect the function of the protein

Amino acid chains then fold and form additional bonds between the amino acids, creating a final three-dimensional shape

The final shape of a protein determines its function

• Proteins with different shapes will carry out different roles within cells

Proteins perform a wide range of essential roles in all living organisms

Examples of protein function include:

• structure: structural proteins provide support, e.g. within tendons, ligaments and skin

• enzymes: enzymes are proteins that function as biological catalysts, e.g. pepsin and amylase in digestion

• hormones: these proteins travel around in the blood and transmit chemical signals to target cells, e.g. insulin

• antibodies: immune proteins that recognise and neutralise pathogens

• receptors: proteins embedded in the cell membrane that bind to specific signals, e.g. hormones, and allow cells to respond