2.4. Proteins

Oxygen, Carbon, Hydrogen and Nitrogen and Sulphur

Are the molecules in which peptides and proteins are built.

• An Amino group(-NH2) • An organic acid group(carboxyl group -COOH) • Side chain includes a_ R group

There are 20 standard Amino acid groups

Tow amino acids combine to form -> Dipeptide The (amino group) of one amino acid reacts with the (Carboxyl group) of another amino acid. remainder /yield = H2O

a reaction in which two molecules combine to form a larger molecule, Bi product= H2O

Sequence of amino acids. Sequence:Determines the shape and the structure of the protein.

Develops when part of polypeptide chain by coiling up take a particular shape eg. a-helix b-sheets these are permanent shapes held in place by hydrogen bonds.

• Made up of complex shape.(folded and held in Place) • Made permanent by four different bonds: • Established between adjacent parts of the atom(Hydrogen bond _Disulfade _Van der Waals_Ionic bond) • Tend to take much coils eg.Fibrous and globular

-This arises when two or more proteins are held together.(Forming a complex, biologically active molecule)

Insulin Rubisco Immunoglobulins Rhodopsin Collagen Spider silk

• The actual proteins made by a cell. • Controlled by expression of genes. • Leads to cell’s phenotype.

• 20 different amino acids • Codons • DNA • mRNA strands

Amino acid Condensation reaction Dipeptide Polypeptide More than one polypeptide 3D shape