1. Molecular Biology l Introduction –Definitions –History –Central Dogma

2. Molecular Biology l Definitions –Chromosomes –DNA –Gene –Genotype –Phenotype

3. Molecular Biology l Chromosomes –The structure in cells that carries hereditary information –Composed of DNA and protein –Prokaryotic - circular –Eukaryotic - linear

4. Molecular Biology l DNA –Nitrogenous base (4 bases - A,T,G & C –Deoxyribose sugar –Phosphate –Nitrogenous bases are paired »AT »GC –Double helix structure

6. Molecular Biology l Genes –Segments of DNA –Functional or regulatory –Mutability and variation

7. Molecular Biology l Genotype –The genetic make-up of an organism; the information that codes for all the characteristics of an organism l Phenotype –The expression or physical manifestation of a gene; how it appears

8. Molecular Biology l Molecular biology seeks to understand the molecular or chemical basis of genetics l History of molecular biology is a melding of biochemistry, especially nucleic acid biochemistry and genetics

9. Molecular Biology l Biochemistry –Meischer –Avery & MacLeod –Hershey & Chase –Watson & Crick l Genetics –Mendel –Sutton –Morgan –Griffith –Delbruck –Beadle & Tatum –Tatum & Lederberg

10. Molecular Biology - Genetics l Mendel (1865) –Fluid vs. particulate inheritance –Studied pure breeding pea plants –Law of Segregation –Law of Independent Assortment –Rediscovered by de Vries & others

11. Molecular Biology

13. Molecular Biology - Genetics Pp PPP purple Pp purple pPp purple pp white Cross of pure breeding purple flowers with pure breeding white flowers produces all purple plants with genotype Pp; crossing Pp plants produces following distribution:

14. Molecular Biology - Genetics l Walter Sutton (1902) –Studied meiosis in grasshoppers (insects have large readily observable chomosomes) –Observed that chromosomes behave in manner similar to segregation of hereditary material –Found that chromosomes occur in morphologically similar pairs –Pairs separate during meiosis

15. Molecular Biology - Genetics

16. l Morgan –Developed modern science of genetics –Used fruit flies because they had a shorter generation time than peas –Discovered sex-linkage –Students developed techniques of mapping genes on chromosomes

17. Molecular Biology - Genetics l Griffith –discovered transformation in 1927 –is a means of genetic transfer in microorganisms –a process by which a nonpathogenic strain is transformed into a pathogenic strain

18. Molecular Biology - Genetics

19. l Delbruck –developed quantitative methods for analysis of bacteriophage; viruses of bacteria –organized course to teach biologists methods at Cold Spring Harbor resulting in a large number of biologists trained in molecular techniques

20. Molecular Biology - Genetics l Beadle & Tatum –developed Neurospora as an experimental organism –established one gene one enzyme hypothesis –generation time is even shorter with Neurospora

21. Molecular Biology - Genetics

23. l Tatum & Lederburg –discovered conjugation in bacteria

24. Molecular Biology - Biochemistry l Meischer (1869) –Austrian doctor –isolated a substance called “nuclein” from the nuclei of cells obtained from the pus of surgical bandages –found to contain nitrogenous chemicals, sugar and phosphate

25. Molecular Biology - Biochemistry l Avery & MacLeod (1944) –isolated Griffith’s transforming factor to a high degree of purity –characterized transforming factor using highly purified enzymes –found transforming factor to be DNA

26. Molecular Biology

27. Molecular Biology - Biochemistry l Hershey & Chase (1952) –used newly developed radioisotopes » 35 S for protein » 32 P for nucleic acid –labeled bacteriophage (a virus of bacteria) –found 32 P went into cells but 35 S did not implying that nucleic acid transfer information to cell for new bacteriophages

28. Molecular Biology - Biochemistry l Watson & Crick (1953) –used X-ray crystallography to study structure of DNA –by combining chemical data and X-ray data were able to construct a model of DNA –structure inferred function leading to Central Dogma

29. Molecular Biology l Central Dogma –DNA Structure –Genetic Code –Replication –Transcription –Translation

30. Molecular Biology l DNA Structure –Sugars –Bases –Phosphates –Double Helix –Anti-parallel

31. Molecular Biology l Genetic Code –4 bases / 20 amino acids –codons –punctuation

32. Molecular Biology Universal Genetic Code

33. Molecular Biology l Central Dogma states a hypothesis regarding information flow in cell l Replication - the copying of DNA or information for next generation l Transcription - the copying of information for use by the cell l Translation - the conversion of information into useful products - enzymes

34. Molecular Biology DNAmRNA Protein Replication TranscriptionTranslation DNA Polymerase RNA Polymerase mRNA tRNA Ribosomes

35. Molecular Biology l Replication –replication is semi-conservative –replication occurs at replication fork –replication is discontinuous process –uses DNA polymerase –Uses RNA polymerase –requires a primer with free 3’-hydroxyl

36. Molecular Biology

37. The Meselson Stahl Experiment

38. Molecular Biology

40. Continuous/Discontinuous DNA Synthesis

41. Molecular Biology l Transcription –RNA polymerase –promoters –produces messenger RNA (mRNA) –requires NO primer

42. Molecular Biology

43. l Differences between prokaryotic and eukaryotic mRNA l Prokaryotic –often polygenic –turns over quickly –translated almost immediately l Eukaryotic post transcription modification –Heterogenous introns & exons - excision of introns –mRNA stability – days to weeks –Addition of 5’ cap and 3’ polyadenylation

44. Molecular Biology l Translation –tRNA –amino acid synthase –ribosomes –initiation –termination

45. Molecular Biology

46. l DNA Sequence Analysis –DNA coding (sense) »5’CCG ATG AAT GTC GAG CTA TCC TAC 3’ –DNA non-coding (nonsense)(template) »3’GGC TAC TTA CAG CTC GAT AGG ATG 5’ –mRNA »5’CCG AUG AAU GUC GAG CUA UCC UAC 3’