Amino Acids

Amino Acids

1. There are over 170 amino acids found in the human body, however, only 20 are commonly used in protein structure

2. Plants are able to make all of the amino acids they need by combining mineral ions with carbohydrates produced in photosynthesis

3. Animals are unable to photosynthesise all of the amino acids that they need and must obtain some from their diet. These are known as essential amino acids

4. All amino acids contain an amino group (-NH2) which has basic properties, & a carboxyl group (-COOH) giving it acidic properties. These groups are attached to a carbon atom

5. The majority of amino acids have one amino group and one carboxyl group producing a neutral amino acid

6. However, some may have more carboxyl groups & will therefore be acidic amino acids and vice versa being basic amino acids

7. They differ in their R groups. In the simplest amino acids when R=a single hydrogen ion, the amino acid glycine is produced, and when R=CH3, the amino acid alanine is produced

8. The R groups which form the side chains are important in determining the shape of the final protein molecules as they determine the bonds that can form between different parts of the same amino acid chain or between different amino acid chains

9. Some side chains are hydrophobic and some are hydrophilic, and some contain sulphur allowing them to form disulphide bridges

10. Amino acids are colourless, crystalline, generally soluble in water but insoluble in organic solvents

11. Joining Together Amino Acids

    • Join together to form long chain polypeptides and proteins. This occurs on ribosomes
    • Using a condensation reaction
    • Joins the 1 amino group to the carboxyl group form the other amino acid to form a peptide bond. This is called a dipeptide
    • This can be repeated many times to form a long chain molecule called a polypeptide
    • No sharp dividing line between a polypeptide and a protein
    • Polypeptide - a single chain of amino acids Protein - several molecules & is often formed into a specific shape