1. Amino Acids - The Building Blocks of Life!  Amino acids are molecules containing both the amide group – NH 2 at one end of the molecule and carboxyl group COOH at the other end of the molecule.  H 2 N – Δ – COOH  The Δ part of the molecule represents various arrangements of atoms.  There are just over 20 different types of Amino Acids.  They join together in condensation reactions to form proteins.

2. Joining Amino Acids H O I II N – R – C + N – R * - C I I H OH

3. The products H O H O I II I N – R – C – N – R * - C + H2OH2O I I H OH They are held together by a peptide link CONH (amide link)

4. Proteins  Proteins are made when thousands of amino acids join by condensation polymerisation.  Very many different types of proteins can be made. ( compare number of possible words with 26 letters. > 20 Amino acids = many different proteins)

5. Types of Proteins  There are 2 main types – Fibrous and Globular  Fibrous Proteins  Long, thin linear molecules.  Hydrogen bonding exists between the COOH and NH 2 groups in near by chains or within the same chain.  Examples – Keratin ( hair, wool, nails) Elastins ( lungs and arteries) Collagens ( skin and tissue)

6. Globular Proteins  They contain intermolecular bonding which can cause the molecule to become a spiral chain.  They are involved in human biological processes.  Examples – Enzymes, hormones and haemoglobin.

7. Enzymes  Enzymes are biological catalyst.  They speed up the rate of reactions in living organisms.  Enzymes are PROTEINS.  They are very specific.  They usually only catalyse 1 type of reaction.  When enzymes are at the wrong temperature or pH – they are denatured ( destroyed).  They work at optimum conditions – pH and T.

8. Lock and Key  Enzymes are so specific because of the “lock and key” model.  The enzyme molecule will only let reactant (substrate) molecule which have the correct shape and orientation.  They form an intermediate complex.  The new substance forms and then leaves the enzyme surface – which can then be reused.  When an enzyme is denatured the shape of the protein molecules, of the enzyme, has changed and the reactants no longer fit.

9. Hydrolysis of Proteins  This is the type of reaction where large protein molecules are broken down back into amino acids. Water is added.  This is what happens to proteins when they are digested.  This enables the smaller molecules to pass into the blood stream.  Some amino acids can not be stored/made in the body, we have to take them, in our diet, on a regular basis – these are essential amino acids.  They are essential for protein synthesis.