Muscle protein Collagen Haemoglobin Keratin Muscle protein Collagen Haemoglobin

Proteins Must: Describe how amino acids are linked together by condensation to form polypeptides. Should: State that there are 20 different amino acids in polypeptides synthesized on ribosomes. Could: State that Amino acids can be linked together in any sequence giving a huge range of possible polypeptides

Animation to illustrate condensation of 2 amino acids http://www.biotopics.co.uk/as/aminocon.html Note this down

Condensation reaction The peptide bond Condensation reaction

Sequence/order of amino acids

Modelling protein structure and synthesis Cut out the mRNA strand and stick it together. Now cut out the 9 amino acid templates, then cut out the 9 R-groups to make 9 specific amino acids. Then use the translation template to work out the order of the amino acids. Cut out the Peptide bonds and use them to link the amino acids together. The Carboxyl group on one amino acid should be linked with the amine group on the next. A water molecule is released as this is a condensation reaction. What you have just modelled is the primary structure of a protein.

Caused by hydrogen bonding between amino acid residues. Will either form alpha helix or beta-pleated sheet

The precise compact structure unique to that protein which arises when the molecule is further folded and held in a particular complex shape. This is strengthened by Ionic bonds, Disulfide bonds, Van Der Waals forces and hydrogen bonds.

Arises when 2 or more proteins become held together, forming a complex biologically active molecule.

Beta pleated sheet

Differences between fibrous and globular proteins Use pages … from your textbook to make a note of the main differences between globular and fibrous proteins.

How many different amino acids are used to make proteins? A – 12 B – 20 C - 32

2.Which parts of amino acids are involved in peptide bonds? A. The carboxyl group on one amino acid and the side chain on the other  B. The carboxyl group on both amino acids  C. The amino group on one amino acid and the carboxyl group on the other  D. The amino group on both amino acids

3.Which part of an amino acid gives it its unique properties? A. The amino group  B. The carboxyl group  C. The side chain 

4.In a folded protein, the nonpolar (hydrophobic) amino acids tend to be: A. tucked away inside the protein.  B. exposed on the outside of the protein.  C. distributed randomly throughout the protein. 

On the dry wipe boards Choose 5 amino acids and make a protein! Link them together with peptide bonds and show how many waters are released.

Testing for protein - In the Biuret test the solution turns purple. 8A What’s in food? Testing for protein - In the Biuret test the solution turns purple. potassium hydroxide copper sulphate shake purple = protein chopped up food