Welcome to Genetics (BIOL 364/564)

1. Dr. Carol Ely Hepfer Welcome to Genetics (BIOL 364/564) Textbook and Study Guide: iGenetics: A Molecular Approach, third edition Author: Peter J. Russel Publisher: Pearson/Benjamin Cummings

2. Materials Available at Desire 2 Learn (D2L) In ‘Content’ Area Syllabus, Handouts, PowerPoint slides, Pencasts Discussions - Group Lockers, Drop Boxes Announcements - Marauder email essential PLEASE - LOG OUT!!!

3. Handouts Syllabus Lecture Slides (available at D2L, not comprehensive) Lab Handouts *Alternative Transformation Protocol*

4. Chi-Chon Biological Study of Inheritance Inherited traits are determined by genes that are transmitted from parents to offspring during sexual reproduction. What is Genetics?

5. Areas of Study within Genetics Population Genetics, Quantitative Genetics Transmission Genetics Molecular Biology Cytogenetics

6. History of Genetics ~~ Agriculture, Breeding 1859 Charles Darwin - ‘Origin of the Species’, evolution, natural selection Gregor Mendel - Research published on inheritance in peas Friedrich Miescher - Discovered nucleic acids Hugo deVries, Carl Correns, Erich vonTschermak - Rediscovered Mendel

7. History of Genetics 1908 Archibald Garrod - ‘Inborn Errors of Metabolism’, defective enzymes cause human diseases 1928 Frederick Griffith - Phenotype transformation observed in bacteria 1944 Oswald Avery, Colin MacLeod, MacLyn McCarty - DNA is the genetic material in bacteria 1952 Alfred Hershey, Martha Chase - DNA is the genetic material in some viruses

8. History of Genetics 1950s Rosalind Franklin, Maurice Wilkins - Xray crystallography of DNA 1953 James Watson, Francis Crick - Deduced three dimensional structure of DNA 1970s Numerous investigators - Deciphered the genetic code Molecular Biology begins 1990s Human genome project initiated - Genomics, Proteomics, etc.,

9. Phenotype - outward appearance of an individual Examples Plant Height - Tall, Dwarf Hair Texture - Curly, Wavy Straight Yeast Metabolism - Produces ASN, Requires ASN Bacterial Resistance - Tetracycline, Ampicillin Gene expression determines phenotype

10. Classification of Phenotypes Wild type (+) = most common phenotype in population, ‘normal’ Whippets Mutant = unusual, variant form, due to changes (mutations) in gene(s) Examples: TraitWild typeMutant Eye color Red White, scarlet, brown Coloration Pigmented Albino

11. Location along a chromosome gene locus Sequences of bases in DNA 5’ ATCGCTGTCAGTCCTAGA 3’ OR 5’ ATCGCTCTCAGTCCTAGA 3’ What is a gene? Mendelian Cytogenetic Molecular Abstract unit of inheritance - A a B b

12. Discovery that DNA is the genetic material Genes - control phenotype, located on chromosomes Chromosomes - composed of DNA, RNA, protein 1940’s - Proteins favored as candidate - sufficiently complex Nucleic acids - too simple

13. Preliminary Evidence in favor of DNA Genes and chromosomes - in nucleus, not cytoplasm Proteins and RNA - in nucleus and cytoplasm DNA - mostly in nucleus

14. Preliminary Evidence in favor of DNA • [DNA]  # of chromatids G1 cells - 1 X [DNA] (unreplicated chromosomes) G2 cells -2X [DNA] (replicated chromosomes) [DNA] in diploid cells = 2x that in haploid cells

15. Preliminary Evidence in favor of DNA Chemical composition of DNA Consistent within each species Same in all cells of an individual RNA and Proteins differ substantially in different cells of the same individual

16. Preliminary Evidence in favor of DNA 4. UV light (260 nm) Wavelength of maximum absorbance for DNA Highly mutagenic

17. Griffith’s Transformation Experiment (1928) Diplococcus pneumoniae Antigen type (II or III) Colony shape Smooth (S) - encapsulated, virulent Rough (R) - no capsule, avirulent

18. Griffith’s Transformation Experiment What is going on?

19. Interpreting Griffith’s Transformation Experiment Could mutations in IIR cells transform them into IIIS? Probability of one mutation ~ 1 in 1,000,000 Probability of two mutations < 1 in 1012 Something from dead IIIS cells ‘transforms’ IIR into IIIS

20. What is Griffith’s Transforming Principle? Avery, MacLeod, McCarty (1944) Extract from virulent (S) bacteria isolated

21. Is it DNA or RNA? RNase DNase Avery, Macleod, McCarty Experiment Extract from III S protease

22. Hershey & Chase Experiment Experimental organism - T2 bacteriophage - composed of protein and DNA

23. Hershey & Chase Experiment Life cycle of T2 bacteriophage

24. Hershey & Chase Experiment Phage inject genetic information into bacteria Is it their DNA or their protein?

25. Hershey & Chase Experiment Allow infection, separate bacteria from phage Centrifuge Centrifuge

26. Identity of Genetic Material Established Most organisms - DNA Some viruses - RNA

27. Chemical Composition and Structure DNA and RNA - polymers of nucleotides Each nucleotide - sugar, base, phosphate Different functional group at carbon #2

28. Chemical Composition and Structure Nitrogenous Bases Purines Pyrimidines

29. Chemical Composition and Structure DNA Nucleosides: deoxyadenosine deoxyguanosine deoxycytidine deoxythymidine Nucleotides: -monophosphate dAMP, etc.

30. Chemical Composition and Structure RNA Nucleotides adenosine monophosphate, uridine monophosphate, etc. AMP, UMP, etc.

31. Chemical Composition and Structure DNA and RNA polymers of nucleotides 3’-5’ phosphodiester linkage

32. RNA is normally single-stranded Secondary structures - intrastrand H-bonding Ex. Stem and Loop

33. Evidence that DNA is double-stranded Chemical composition Chargaff (1947) [C] = [G] [A] = [T]

34. Evidence that DNA is helical Physical chemistry - Franklin & Wilkins (1952)

35. Xray diffraction helical structure 20 A diameter highly ordered repeating units 3.4 A 34 A Note: 1 A = 0.1 nm O O O Evidence that DNA is helical O

36. Watson and Crick Model building to deduce structure (1953)

37. Watson and Crick Model for DNA DNA B right-handed

38. Specific Base Pairing in DNA Hydrogen Bonding A with T C with G

39. Arrangement of DNA strands Antiparallel Complementary 5’ TGTA 3’ 3’ ACAT 5’

40. Different Forms of DNA A-DNA B-DNA Z-DNA left-handed loose coiling right-handed tight coiling

41. Organization of Chromosomes - Viruses dsDNA, ssDNA, dsRNA, ssRNA circular, linear single chromosome, segmented genome T-even phages (T2, T4, T6) - dsDNA, 1 linear chromosome X174 - ssDNA, one circular chromosome Lambda () - dsDNA, alternates linear and circular

42. Organization of Chromosomes - Prokaryotes Most - single circle, dsDNA Some - linear Extra chromosomes, Plasmids Cells Divide by Binary Fission 42

43. Organization of Chromosomes - Prokaryotes A. tumefaciens - 1 circular + 1 linear chromosome (3.0 Mb) (2.1 Mb) E. coli - 1 circular chromosome + circular plasmids (4.6 Mb) 43

44. Organization of Chromosomes - Prokaryotes DNA supercoiled into nucleoid region of cell

45. Organization of Chromosomes - Eukaryotes Replicated metaphase chromosome

46. Organization of Chromosomes - Eukaryotes DNA supercoiled to fit into chromosomes Relaxed DNA in haploid (1n) human cell = 1 meter long DNA in largest chromosome = 82 mm long Metaphase chromosome = 10 m long Analogy: 25 miles of rope coiled into 2 ft x 16 ft canoe 46

47. Chromatin - DNA supercoiled with proteins Histones - small, basic (+), bind DNA (-) H1, H2A, H2B, H3, H4 Nonhistones - all other associated proteins - many acidic (+), bind histones - include those for repair, replication, etc. Organization of Chromosomes - Eukaryotes

48. Nucleosome Structure DNA (147 bp) wrapped around histone octamer 10 nm chromatin fiber - string of nucleosomes

49. Chromatin Structure 10 nm chromatin fiber - condensed with H1 30 nm chromatin fiber - solenoid model

50. Metaphase chromosome with histones removed Nonhistone scaffold Chromatin in Metaphase Chromosome