This document discusses protein structure and function. It begins by stating the aim is to understand how proteins fold into their correct shape. It then lists several important functions of proteins, including serving as enzymes, transporting molecules, storage, movement, structure, and mediating responses and immunity. The document goes on to explain the four levels of protein structure: primary structure is the amino acid sequence; secondary structure involves hydrogen bonds forming alpha helices and beta sheets; tertiary structure is the complex 3D shape formed by additional bonds; and quaternary structure refers to large proteins made of multiple polypeptide chains. Examples of hemoglobin and collagen are provided.

1. Protein Structure Review
Aim – to understand how proteins are folded into their
correct shape
Starter – Without looking in your notes draw and amino
acid

2. Why are proteins so useful?
They have many different purposes.
1. They serve as enzymatic catalysts, eg pepsin which breaks
down protein.
2. They serve to transport, eg haemoglobin transports
oxygen.
3. They serve as storage, eg iron is stored in the liver as a
complex with the protein ferritin.
4. They are used in movement. Proteins are the major
component of muscles.
5. Skin and bone are made of a fibrous protein called
collagen.
6. They mediate responses, eg rhodopsin which is a protein
located in the eye.
7. Antibodies are proteins if the immune system.
8. Hormones are proteins of the endocrine system.

5. Primary Structure
• The sequence of amino acids that forms the
protein

6. Secondary Structure
• An a-helix
coil.
• H Bonds form
between the
–NH group
and the –C=O
group.

7. Tertiary Structure
• More complex 3-D structure.
• Structure maintained by several different
bonds.
• Disulphide bonds – strong, not easily broken.
• Ionic bonds – formed between carboxyl and
amino groups. Weak and easily broken.
• Hydrogen bonds – numerous, weak and easily
broken.

9. Quaternary Structure
• Structure of large proteins.
• Number of different polypeptide chains linked
together in various ways.
• May contain a prosthetic group (not a protein)
e.g haem group in haemoglobin.

13. HOW WOULD YOU BUILD AN
ENZYME?

14. Haemoglobin...

16. Collagen...