1. POLYPEPTIDES AND PROTEINS A condensation reaction between two amino acids forms a peptide bond. Polypeptides are formed by the condensation of many amino acids. A functional protein may contain one or more polypeptides. The role of hydrogen bonds, ionic bonds and disulfide bridges in the structure of proteins. Proteins have a variety of functions within all living organisms. The relationship between primary, secondary, tertiary and quaternary structure, and protein function. The Biuret test for Proteins

2. Starter: Proteins are not simple  Match up these post its to their definitions: Outcomes: -Name the monomers and bond that polymerises to form polypeptides -Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins. -Explain the role of a protein is entirely dependent on its structure/shape. -Outline the test for proteins

3. Primary Structure  The sequence of amino acids joined together is referred to as primary structure. Outcomes: -Name the monomers and bond that polymerises to form polypeptides -Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins. -Explain the role of a protein is entirely dependent on its structure/shape. -Outline the test for proteins

4. Secondary Structure  The amino acids form into 3-d structures. Held together by hydrogen bonds  Alpha-helix  Beta pleated sheets Outcomes: -Name the monomers and bond that polymerises to form polypeptides -Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins. -Explain the role of a protein is entirely dependent on its structure/shape. -Outline the test for proteins

5. Tertiary Structure When the polypeptide reforms into a 3-D structure and coils up in a specific structure  The chains of the polypeptide can link up and form bonds to help form the shape. Outcomes: -Name the monomers and bond that polymerises to form polypeptides -Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins. -Explain the role of a protein is entirely dependent on its structure/shape. -Outline the test for proteins

6. Quaternary Structure  When 2 or more polypeptides join together  Same bonds as tertiary structure  Complex polypeptides THIS IS A PROTEIN Outcomes: -Name the monomers and bond that polymerises to form polypeptides -Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins. -Explain the role of a protein is entirely dependent on its structure/shape. -Outline the test for proteins

7. Summary of Structure  Identify the different structures here: Outcomes: -Name the monomers and bond that polymerises to form polypeptides -Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins. -Explain the role of a protein is entirely dependent on its structure/shape. -Outline the test for proteins

8. Structure → Function  The 3-d secondary, tertiary and quaternary structure of a protein is determined by the sequence of amino acids in the primary structure.  The shape of each protein is extremely specific and unique!  Why is protein structure so important? Outcomes: -Name the monomers and bond that polymerises to form polypeptides -Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins. -Explain the role of a protein is entirely dependent on its structure/shape. -Outline the test for proteins

9. Testing for Proteins Testing the sample  Add 2 cm3 of the liquid food sample to a clean, dry test tube  Add 2 cm3 of Biuret Reagent. Testing a negative control  Repeat the steps above with de-ionized water to prepare a negative control Testing a positive control  Repeat the steps above with albumin (egg white) to prepare a positive control.  Shake well and allow the mixture to stand for 5 minutes. Observe any color change. Outcomes: -Name the monomers and bond that polymerises to form polypeptides -Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins. -Explain the role of a protein is entirely dependent on its structure/shape. -Outline the test for proteins Biurets reagent is used to test for… How it works: What is the importance of using positive and negative controls?