1. Proteins, DNA & the Genetic Code

2. By the end of this lesson you should be able to demonstrate an appreciation of: The huge variety of proteins & their diverse properties How these depend upon their amino acid sequences The “one-gene-one- polypeptide” hypothesis What a code does The structure of DNA How the base sequence of our DNA encodes the structure of the proteins – which make possible life.

3. Previous Knowledge: Structure of proteins (yr 12) Schematic structure of DNA (yr11) Cell microstructure (as seen with T.E.M.) (yr 12)

4. nucleus Human cheek cells cytoplasm (light microscope, 400x)

5. Ribosomes on rough endoplasmic reticulum Electron microscope, 70 000x

6. Each of the experiments A - E involves one from: haemoglobin keratin collagen gelatine catalase casein 1.Match one of these chemicals to each experiment 2.What do all these chemicals have in common? Diverse and Shapely Molecules They are all proteins

7. Enzymes: e.g. catalase “active site” binds around... substrate.. molecule

8. There are 10 000 different types of enzyme in your liver cells! Each one acts as a catalyst to a different chemical reaction

9. Casein in Milk

10. Collagen

12. Keratin

13. Haemoglobin

14. Antibodies Virus Antigen Antigen binding sites

15. What ever life throws at you – there’s a protein for it!

16. Proteins make possible life.

17. Snakes! You have beads of four colours, how many different types of snake, five beads long, can you make in two minutes? If you had time and enough beads, how many different types of five bead snake would it be possible to make? 1024 4 5 = 4x4x4x4x4 = 1024

18. Protein molecules are built from amino acids – there are 20 types

20. There are 20 types of amino acids A typical protein is a chain of around 200 amino.... acids. How many different proteins are possible? 20 200

21. 20x20x20x20x20x20x20x20x20x20x20x20x20x20x20x20x20x20x20x20 =1607 x 10 257

22. 160700000000000000000000000000000000000 000000000000 0000000000000000000000000000000000000000

23. 1024 4 5 = 4x4x4x4x4 = 1024 “One-Gene-One-Polypeptide-Theory” Beadle and Tatum 1941 (USA) Archibald Garrod 1909 (England)

24. Keratin How do your hair cells know how to make your sort of keratin?

25. Each gene instructs a cell in what sequence to assemble the amino acids to make one particular protein - The One –Gene-One-Protein-Theory

26. DNA Cracking the Code!

27. Cracking the Genetic Code A code stores information in a different form A gene is a length of DNA Each gene stores the sequence of amino acids for a particular protein. You are about to crack the genetic code! You will be able to read a piece of DNA (a gene) to find the sequence of amino acids it encodes

28. ..-./.-./.-/-./-.-./../…//-.-./.-./../-.-./-.- The name of a famous scientist is written in Morse code, below. Key: Francis Crick

29. -.-./..../.-/.-./.-../. /…//-../.-/.-./.--/.. /-. The name of a famous scientist is written in Morse code: Key: Charles Darwin

32. Part of a DNA Molecule Template strand Coding strand Its sequence of bases encodes the sequence of amino acids in a protein It is used to make copies of the coding strand

33. Template strand Coding strand Part of a DNA Molecule A G C G T G C T G A C A C G Sequence of bases:

34. The Genetic Code: A triplet of bases on your DNA codes for each type of amino acid The 20 Types of Amino Acid The Genetic Code (Start)

35. DNA Code Key: Triplet of bases Amino acid sequence of bases in DNA: A G C G T G C T G A C A C G sequence of amino acids in protein: Ser Val Leu Thr (Start)

37. A woman with diabetes Insulin

38. A chain B chain The Protein Insulin: Diagram showing the sequence of amino acids in a molecule of insulin

39. Human Insulin Molecule: Sequence of amino acids A chain B chain

40. 1.Choose two contrasting proteins and relate their roles and properties. 2.Explain what determines their different properties. 3. What is meant by the “one-gene-one polypeptide” theory 4. Describe how a length of DNA encodes the primary structure of a protein. 5. The genetic code is “degenerate” and “non-overlapping” - what do these terms mean. Explain why each of these is significant.