Franklin’s photo below proved model on left to be correct for DNA

1. Crick Watson Franklin Wilkins Franklin’s photo below proved model on left to be correct for DNA Pauling

2. First time DNA double helix seen in print Most important scientific paper in Biology in last 100 years By Watson and Crick, 1953

3. 2 April 1953MOLECULAR STRUCTURE OF NUCLEIC ACIDS A Structure for Deoxyribose Nucleic Acid “We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest.” From the original Watson and Crick article – first published “double helix” diagram

4. Proof of double helix

5. Summary of a few people involved with DNA: Pauling and Corey – “telephone pole” model for DNA Franklin – x-ray photos proved Pauling wrong Wilkins – gave x-rays to Watson and Crick Watson, Crick, Wilkins – Nobel Prizes for DNA structure Watson & Crick Pauling and Corey

6. Rosalind Franklin 06 Lise Meitner Nobel Prize Otto Hahn Nobel Prizes First to discover structure of DNA First to describe the physics to split the atom

7. Basic Terms: DNA Nucleotide (monomer) Subcomponents of nucleotide sugar = deoxyribose phosphate bases – 4 of them adenine (A) guanine (G) cytosine (C) thymine (T) Nucleic Acid (polymer) – chain of nucleotides Double helix – two chains of nucleic acids

8. Nucleic acid (polymer) = chain of nucleotides (monomers) B B B B B S P S S S P S P P P B Base = A, G, C, T phosphate Nucleotide (DNA or RNA) S P sugar DNA Nucleotide

9. Nucleic acid Sugar phosphate base Double helix of nucleic acid Nucleotide

10. Base Pairing in DNA double helix G-C A-T C-G T-A

11. Only one base pairing is possible

12. Nucleosome = protein + DNA Protein DNA Nucleosome (a)

13. Nucleosomes

14. Heterochromatin = inactive DNA = condensed Nucleosome DNA Euchromatin = active DNA = decondensed Fig. 13.11

15. DNA Replication

16. DNA replication: One double helix forms two identical double helices

17. Double Helix separates New strands forms by base pairing

18. T A C A T G C A G Double helix separates T A T

19. Base pairing New nucleotides are added to the “old” or original DNA nucleotides by base pairing with the help of enzymes (not shown here)

20. normal Mutant Fig. 11.08

21. Protein Synthesis

22. Review Protein gives life structure Protein gives life function Amino acid sequence gives protein its structure and function Question: How is amino acid sequence determined?

23. Yeast Fruit Fly Worm Green Plant 6034 genes 13,061 genes 19,099 genes 25,000 genes Gene = section of DNA that codes for amino acid sequence in a protein

24. DNA (m)RNA (copy) Protein Transcription Translation

25. Overview Retire already!!!

26. Sugar–phosphate backbone Base pairing is the genetic code G-C C-G A-T T-A

27. DNA double helix separates RNA nucleotides attach to DNA T replaced by U Base pairing makes RNA copy of DNA

28. Transcription = (m)RNA copy of one side of DNA

29. Transcription of mRNA DNA mRNA transcript DNA

30. Codon = three RNA nucleotides = code for particular amino acid

31. Translation – conversion of mRNA nucleotide sequence (codons) into amino acid sequence of protein

32. Codon – group of three mRNA nucleotides Each amino acid has at least one specific codon. Alanine (Ala) has the codon GCU. Glycine has the codon GGU Tyrosine has the codon UAU

33. review Codon = three RNA nucleotides = code for particular amino acid

34. Translation = mRNA codons place amino acids in proper order review Nontranscribed strand 5’ Transcription DNA 3’ Transcribed strand Codon 1 Codon 2 Codon 3 Codon 4 Codon 5 Codon 6 Polypeptide Translation

35. UV-A UV-B Sun screen products Human skin

36. A C G T T C C A T G C A A G G T Thymine Dimer mutation DNA from U.V. light UV light A C G T T C C A T G C A A G G T

37. Thymine dimer Thymine dimer removed DNA repair enzymes New DNA replaces hole left by damaged DNA

39. Every cell in the body has the same DNA, but each specific type of cell makes proteins unique to those cells? In other words every cell in your body has the exact same book of blueprints but only certain pages are read in certain cells.

40. Human embryos are totipotent = can become any cell in the human body Why? because it has DNA to make every cell in the body. http://www.dynamist.com/aaa/blastocyst.gif

41. 4 week old embryo is pluripotent – produce most cells 6 day old embryo is totipotent – produce all cells

42. Salamander – many tissues can be regenerated if damaged.

43. Salamander can re-grow new limbs because adult stem cells behave like embryonic cells. http://www.luc.edu/depts/biology/dev/regen.gif

44. Heterochromatin - inactive Salamander leg cells damaged Nucleosome Euchromatin - active DNA Transcription of DNA to make new leg

45. Polymerase Chain Reaction

46. Small amount of DNA left at crime scene Polymerase Chain Reaction (PCR) DNA replication After 20 replications (a few hours) – over 1,000,000 helices formed

47. DNA DNA Restriction enzyme (Eco R1) cuts DNA into fragments

48. DNA fragments loaded into wells in gel (like Jell-O) Fragments (-) migrate through gel because of electric current

49. DNA fragments have (-) charge (-) (+)

50. DNA fingerprinting – compares fragments of DNA formed by restriction enzymes Like a barcode