Molec . Genetics L.Os (Ch. 16)

1. Molec. Genetics L.Os (Ch. 16) • Students need to understand the basic structure of DNA. Look at Figure 16.7 • DNA replication is “semi-conservative” • DNA replication is facilitated by a host of enzymes (Table 16.1 and Figure 16.6) • If time remains, teach “the road to the Double Helix”

2. The Cell Cycle You are here (in Chapter 16)

3. Watson and Crick (with a little help from Rosalind Franklin) • Who they were… • X-ray Crystalography (fig 16.6)…

5. What did Watson and Crick See in that Image?

6. What about the uniformity of the Double Helix?

7. Some more information • Chargaff’s Rules: • Every organism… • The Ratios of A-T and G-C

8. W & C also figured out that replication was “semi-conservative”DNA is a…

9. Replication Up Close 5’ 3’

10. Semi-Conservative Nature of DNA Replication • What Does “semi-conservative” mean?

11. DNA Replication: The Players

12. Leading Strand Replication Important Point (see next slide)

13. Bacterial DNA Replication 5’ to 3’ Past Present

14. What About Bacteria ()?

15. Molecular Genetics L.O.s (Ch 17) • Jump right in on Page 311, Basic principles of transcription and translation. This is very straightforward. Students should know the basic components of the “Central Dogma of Molecular Biology” • They should be able to read a sequence of DNA and write out the correct polypeptide using a genetic code chart. • 2a) Transcription: DNA directed, and Protein mediated, synthesis of mRNA. Focus on the three main steps: Initiation, Elongation and Termination. Figure 17.7 is the essential figure here. • 2b) mRNA splicing. Prokaryotes don’t splice mRNA, eukaryotes do splice mRNA. • 2c) Translation: RNA directed synthesis of a polypeptide. You’ll need a good animation to teach this, I like: http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html it’s simple, but get all the points across. • 2d) Discuss the role of polyribsomes…a little bit of mRNA can go a long way.All protein synthesis starts in the cytosol, however…Fig 17.21 • Students need to be able to differentiate between silent mutations, mis-sense mutations and non-sense mutations.

16. Examples of: DNA RNA PROTEIN

17. DNA RNA PROTEIN Beadle and Tatum: worked with enzymatic pathways in Neurospora…(Fig 17.2) They concluded…”one gene one enzyme” It’s been modified to…one gene, one gene product…(unless you consider alternative gene splicing and gene regulation

18. An overview: DNA RNA PROTEIN

19. “The Central Dogma”THE FLOW OF GENETIC INFORMATION

20. Why RNA? • Protect the original copy! (DNA) 2. Multiple RNA transcripts can be translated simultaneously 3. RNA can be edited and spliced, even shuffled, but you don’t want to make changes to the original copy.

21. How is the Genetic Code Deciphered? How was the code cracked?

22. Central Dogma 1: Transcription 3 Key Terms: (I, E, T)

23. Central Dogma 1: Transcription (2) 10-20nucleotides RNA polymerase 60 nuc/sec!

24. Central Dogma 2: RNA Processing Transcription Arithmetic Average Primary Transcript: 8 kb (or 8000 bp) Average polypeptide is: 400 aa Average processed mRNA that leaves the nucleus is:

25. How DoesSplicingOccur?

26. The $64,000 Question: WHY INTRONS? • Regulation of genetic expression • Alternative RNA Splicing!, which means… • 1 gene, multiple proteins • Exon Shuffling! • Distance between exons increases probability of recombining useful exons during meiosis.

27. Central Dogma 3: Translation • The Players:

28. The Players: t-RNA

29. The Players: Ribosomes! • r-RNA Rules! • l-su • s-su

30. Translation of polypeptides: 3 steps • Initiation initiation factors • Elongation elongation factors • Termination release factors (the same as transcription)

31. Translation 1: Initiation N C

32. What becomes of polypeptides? DNA RNA polypeptide protein protein modification

33. One view of “protein regulation” All proteins start of…

34. Role of RNA • messenger RNA -- • transfer RNA -- • ribosomal RNA -- • Primary Transcript -- • Small nuclear RNA (snRNA) -- • SRP RNA --

35. DNA RNA PROTEIN

36. Mutations • Specifically point mutations… • Base pair mutations • Silent • Missense • Nonsense

37. Examples of point mutations

38. Sickle Cell Anemia: a great example of missense

39. Insertions and deletions • Much more devastating • Because they lead to… • So what… • Examples

40. Application of Gene to Protein and microbial genetics. Learning Objectives (Ch. 18) • Bacteria have one chromosome, and speed of replication is of the essence. Speed of replication leads to mutation, and this provides raw material for natural selection. • In addition to spontaneous mutation, genetic diversity of bacteria is caused by transformation, conjugation, transduction and transposition. • Although bacteria don’t have introns, they can control gene expression. The most basic way bacterial cells control gene expression is through operons. Students need to understand both inducible and repressible operons. • Students should be familiar with different types of viruses. Focus on phages and retroviruses.

41. The pGLO plasmid exploits a characteristic of bacterial DNA called (Inducible) operons • An operon is… • It consists of… • But it’s under the Influence of…

42. Other operons are repressible • Meaning… • How do they work?

43. Key Similarities and Differences between three types of Operons p. 355

44. Operons are only part of the bacterial genome • What else do we know about E. coli • Size/number of genes: 100kb; ≈ 4000 genes • So what? • How E. coli packs the DNA into a into the cell: • Supercoiling via isomerase, • How it replicates:binary fision (see ch. 16) • How fast it replicates: lab (optimal): 30 min • human colon (pretty darn optimal): every 12-24 hours

45. A quick look at Binary Fission

46. Question: If mutation is the raw material for natural selection, where do the mutations happen?Answer: virtually anywhere

47. So what? Increases genetic diversity in a constantly changing environment and… Increases genetic diversity in an assexually reproducing organism New mutations, though individually rare, can significantly increase genetic diversity (of a population) when reproductive rate is very high. This diversity, in turn, affects the evolution of bacterial populations…because individuals who are genetically equipped for a local environment will reproduce more prolifically than other, less fit individuals.

48. What are other sources of genetic diversity? Genetic Recombination! • Transformation • Transduction • Conjugation and Plasmids • (F plasmids and R plasmids) • Transposition

49. Transduction • The virus is the vector! • How can bacteria defend against viral (phage) attack?

50. Conjugation: Plasmid Transfer • F+ Cells = • Hfr Cells = • R Cells =