Proteins – What do you know? Sources in diet Meat, fish, beans, cheese Functions To make enzymes Receptor proteins (see cell membranes topic) Muscle Other info Proteins made of amino acids Plants make amino acids (sugar + nitrates) Contain the element carbon Protease breaks down protein (and builds it up) As enzymes – can have specific shape, shape destroyed by high temp and incorrect pH

Learning objective To know about the primary structure of proteins Success Criteria I can describe the structure of an amino acid I can describe the formation and breakage of peptide bonds I can explain the term primary structure

Amino Acids Carboxyl group Amino Group R Group Acid group also known as carboxyl group

Examples of different side chains Valine Phenylalanine

Amino Acids Use the whiteboards to draw the structure of an amino acid from memory Get your partner to check and correct any incorrect parts R Group Carboxyl group Amino Group

Formation of a dipeptide ` Use your knowledge of the formation of both glycosidic and ester bonds, to suggest how a dipeptide bond is formed… Condensation Reaction Hydrolysis Reaction Peptide Bond + H20

Hydrolysis of Peptide Bonds The covalent bond that forms the peptide bond is strong, it must be broken apart by an enzyme Enzymes that breakdown proteins are called proteases Examples of protease activity other than digestion: Hormone regulation Ageing

Draw a diagram to show the hydrolysis of a peptide bond in a dipeptide Include the following: The name of the enzyme that breaks the peptide bond What is needed along with the enzyme Label the amino group Label the R group Label the carboxyl group

Protein Structure Primary structure - sequence of amino acids in the chain Every protein has a unique order of amino acids in its primary structure. The function of each protein is determined by it’s structure – that is, the amino acid sequence that makes up the primary structure

Quick Check Draw and label an amino acid? Describe the synthesis and hydrolysis of polypeptides? Explain the term ‘primary structure’?

PPQ