1. 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

2. 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

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

4. Examples of different side chains
Valine
Phenylalanine

5. 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

6. 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

7. 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

8. 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

9. 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

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

11. PPQ