STARTER . You are about to see an animation on protein structure

1. STARTER. You are about to see an animation on protein structure Try and match the following key terms with the definitions given -primary structure -secondary structure -tertiary structure -quaternary structure -alpha helix -beta pleated sheet

2. Learning Objectives Everyone should • Statefour functions of proteins, giving a named example of each Most will • Outlinethe difference between fibrous and globular proteins, with reference to two examples of each protein type. Some might • Explainthe significance of polar and non-polar amino acids. • Explainthe four levels of protein structure, indicating the significance of each level.

11. Starter – TeamActivity Youhave 5 min to complete Steps A and B of Proteinmodellinghandoutonyourbench in teams • Alina and Lucia • Andrea , JP and Natalia • Work in a team BUT complete yourownhandout INDIVIDUALLY

12. Learning Objectives Everyone should • Statethe four levels of protein structure Most will • Describe the four levels of protein structure, indicating the features of each level. Some might • Explainhow polar and non-polar amino acids determine the folding of a polypeptide to produce a functional protein

13. Primarystructure of a protein • To simulate a protein, you will make a model of your protein using plasticine beads • Refer to the sequence of 15 amino acids (the colored circles on Step C of your worksheet) Complete Step C firstifyouhaven’talreadyusingthe amino acid chart provided • Arrange beads of the appropriate colors on the pipe cleaner. (substitute yellow for green) • The beads should be approximately evenly spaced the along the pipe cleaner.

14. Secondarystructure of a protein • Twist one half of your protein model around a pencil to make a spiral. • Bend the other half of your protein molecule into a zig-zag shape by making a bend in the opposite direction at each bead. • Make a drawing to show the secondary structure of your protein model (Step D of your worksheet). • Label the alpha helix region and the beta-pleated sheet region on your drawing.

15. TertiaryStructure • Twist your protein into a 3-D shape according to the protein folding ruleson the chart • Make a drawing to show the tertiary structure of your protein model (Step D of your worksheet). • Note: Do the best you can to make your 2-dimensional drawing look like your 3D model.

16. QuarternaryStructure • Some protein chains are attracted to other protein chains. • Work with the other team and try putting your protein model next to their protein model in a way that still follows the rules of protein folding. • Make a drawing to show the quaternary structure of your protein model (Step D of your worksheet).

17. Plenary – Ticket toExit! • Filloutyourtablewithoutusingyour notes • Try and incorporate as manykeytermsfromthetopic as you can

18. PLENARYExplainthe four levels of protein structure (10) • primary structure is sequence / number of amino acids; • determined by base sequence in the gene; • (largely) determines higher level structures/secondary structure/tertiary structure; • secondary structure is regular repeating patterns; • such as alpha/α helix and beta/β (pleated) sheet; • determined by H bonds (within chain); • tertiary structure refers to overall 3-D shape; • conformation can determine function; • tertiary structure determined by R-group interactions / ionic interactions /hydrophobic interactions / disulfide bridges / H-bonds; • quaternary structure is only found in proteins formed from more than onepolypeptide; • e.g. hemoglobin; (accept other suitable example)

19. Starter– sortthestatementsintoyourtable (q7)

20. Learning Objectives Everyone should • Statefour functions of proteins, giving a named example of each Most will • Outlinethe difference between fibrous and globular proteins, with reference to two examples of each protein type. Some might • Explainthe significance of polar and non-polar amino acids in biological molecules

25. GROUP ACTIVITY: Usingyourwhiteboards – can youdraw a diagramtoexplainhowthey do this?

26. Nowlets try somePPQs (Q9-11) Forquestion 11.c – pleasechangethewordCHANNELtothewordMEMBRNE

27. Mark scheme 9. Describe a polar molecule. Has charge 10. In the space below, draw and annotate a simple diagram to explain how polar molecules aid enzyme function.

28. 11. a) The hydrophobic tails of the plasma membrane reject polar molecules: they do not allow them to pass through the membrane into or out of the cell. Define hydrophobic. Lacksanaffinityforwater b) Identify labels I to IV as being polar or non-polar. polar polar Non-polar Non polar

29. c) Using the diagram, explain the significance of polar molecules in MEMBRANEproteins. (8) • membrane is a lipid bi-layer; • membrane has hydrophobic interior / lipid hydrophobic tails oriented inward; • hydrophilic on cytoplasmic and extracellular side / lipid hydrophilic heads oriented • outward; • polar amino acids are hydrophilic/water soluble/attracted to outside of membrane; • non-polar amino acids are hydrophobic/attracted to inside of membrane; • integral proteins embedded in the membrane; • peripheral proteins associated with surface of membrane; • non-polar amino acids cause proteins to be embedded in membrane; • polar amino acids cause parts of proteins to protrude from membrane; • transmembrane proteins have both polar and non-polar amino acids; • polar amino acids create channels through which (hydrophilic) substances/ions • can diffuse;