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Unformatted text preview: 204-325 1 Summary of the Last Lecture Conjugation is the unidirectional transfer of DNA from F+ donor to F- recipient through a physical bridge between bacterial cells. Transformation is the transfer of extracellular "naked" DNA into organisms. Transduction is the transfer of DNA between bacteria mediated by bacteriophages. Genetic mapping in bacteria and bacteriophages is based on recombination as well. Intragenic recombination demonstrated that the unit of mutation and recombination is the base pair in DNA.
2 Today's Topics 1. The Search for the Genetic Material:
Avery Experiment Hershey-Chase Experiment 2. The Molecular Structure of DNA and RNA 3. Packaging of DNA into Chromosomes 4. Centromere and Kinetochore 3 Topic 1 The Search for the Genetic Material
Avery Experiment Hershey-Chase Experiment
4 The Question What is the Chemical Nature of the Genetic Material?
DNA? RNA? Protein? Polysaccharide?
5 Streptococcus Pneumoniae 6 Griffith's Transformation Experiment 7 DNA, not RNA, is the Transforming Principle 8 Animation 1: Avery Experiment 9 Bacteriophage T2 10 Hershey-Chase Experiment 11 Animation 2: Hershey-Chase Experiment 12 Tobacco Mosaic Virus (TMV) 13 RNA is the Genetic Material for TMV 14 DNA or RNA is Genetic Material Genetic Material is Nucleic Acids Cellular Organism: DNA Virus: DNA or RNA 15 Topic 2 The Molecular Structure of DNA and RNA
16 Deoxyribose and Ribose, and Bases in DNA and RNA
Sugar Base 17 Backbone and Polarity 5' Base Polarity Sugar Sugar-Phosphate Backbone
18 3' Chemical Structures of DNA and RNA
, , 19 Components of DNA and RNA 20 X-ray Diffraction 21 Franklin and the DNA Diffraction Pattern 22 DNA Double Helix (1953) 23 Complementary Base Pairs and Chargaff's Rule Chargaff's Rule [A]=[T] [G]=[C] 24 Molecular Structure of DNA
right hand helix
2 nm bases inside antiparallel backbones 25 End View and Side View of DNA 26 A, B and Z Forms of DNA 27 Topic 3 Packaging of DNA into Chromosomes
28 Different Levels of Genetic Material DNA Gene Chromosome Genome
29 From DNA to Chromosome Viral Chromosomes Prokaryotic Chromosomes Eukaryotic Chromosomes 30 Bacteriophage 31 Phage Chromosome Changes from Linear to Circular Form
Virus Chromosomes: RNA or DNA Single stranded or double stranded Circular or Linear Single or Multiple Chromosomes 32 Supercoil of Circular DNA Supercoil of DNA 33 Animation 3: Supercoil 34 Looped Domains in Bacterial Chromosome Negative Supercoiled in E. coli 35 E. Coli Chromosome 36 Chromosome Released from a Lysed E. coli 37 Challenge: Fit all the DNA into a Cell 38 From DNA to Metaphase Chromosome in Eukaryote nucleosome 39 Histones and DNA Form Nucleosomes in Eukaryotes Histone Protein Core
40 Nucleosome Histone Proteins 41 "Beads-on-a-String" Form of Chromatin = Chromatin = DNA + histones + other proteins (~1:1:1 in weight)
42 Condensation by H1 Binding 43 The 30-nm Chromatin Fiber 1 2 6 4 5 3 Top View Side View 44 Looped Domains Anchored to the Scaffold 45 Further Condense during Metaphase of Mitosis
30 nm fiber 46 Many Orders of Chromatin Packing
Decondensation 30 nm Chromatid Condensation
47 Metaphase Chromosome without Histone 48 Topic 4 Centromere and Kinetochore
49 Centromere and Telomere
Telomere Telomere 50 Centromere Holds Sister Chromatids Together 51 DNA Sequence of Yeast Centromere R=A or G CEN
CEN is divided into 3 CDEs (Centromere DNA Element) 52 Kinetochore (Protein Structure) Connects Centromere to Spindle CDEI CDEII CDEIII 53 Summary The cellular genetic material is DNA. The viral genetic material is either DNA or RNA. DNA molecules exist in double helix structures, with anti-parallel backbones and hydrogenbonds between complementary base pairs. RNA is structurally similar to DNA, but the sugar and one of the base is different from DNA. Cellular chromosomes are packed by supercoiling and folding of DNA. Histone proteins and DNA form nucleosome in eukaryotes The centromeric regions of eukaryotic chromosomes contain repeated sequence bound by kinetochore during cell division.
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