1. describe the chemical structure of proteins proteins always contain the chemical elements carbon (C), hydrogen (H), oxygen (O) and nitrogen (N) – they often contain sulphur (S) proteins are constructed of amino acid sub-unitsamino acid strong peptide bonds link amino acids together into chains a chain of amino acids is called a polypeptide bonding between amino acids in the same chain results in folding the sequence of amino acids determines the proteins structure and functionsequence

2. state the structural differences between fibrous and globular proteins fibrous proteins are formed when polypeptide chains form parallel strands globular proteins consist of several polypeptide chains folded together into a spherical shape – like a ‘ball of string’

3. provide examples of fibrous and globular proteins and their role fibrous proteins fibrous proteins have structural properties as a result of their strength collagen – strong and inelastic – found in bones (provides rigid support) and in tendons / ligaments (for attachment) elastin – strong and elastic – found in artery walls (provides flexible support)

4. globular proteins amylase (enzymes – speed-up biochemical reactions)amylase insulin (hormones – act as chemical messengers)hormones immunoglobulin (antibodies – defend body against microbes)antibodies membrane proteins (structural, receptors)membrane proteins conjugated proteins are globular in structure with associated non-protein element – haemoglobin ( haem group containing iron – oxygen transport in blood)haemoglobin types of protein