* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download DNA Structure
Survey
Document related concepts
Zinc finger nuclease wikipedia , lookup
DNA repair protein XRCC4 wikipedia , lookup
DNA sequencing wikipedia , lookup
Eukaryotic DNA replication wikipedia , lookup
Homologous recombination wikipedia , lookup
DNA profiling wikipedia , lookup
DNA nanotechnology wikipedia , lookup
DNA replication wikipedia , lookup
DNA polymerase wikipedia , lookup
United Kingdom National DNA Database wikipedia , lookup
Microsatellite wikipedia , lookup
Transcript
III. DNA AND CHROMOSOMES DNA Structure and Replication • 18th C: Friedrich Miescher (nuclei from WBC in pus…Material (nitrogen/phosphorus = “nuclein”) • 1928: Frederick Griffith: transformation experiments with bacteria (Genetic material = DNA) DNA (Deoxyribonucleic Acid) • • • • The “blueprint of life” Unique and unrepeatable Genes: bits of DNA Composed of nucleotides Sugar (deoxyribose) + phosphate + bases Covalent Bonds between S-P Complementary Base Pairs (AT, CG) Purines (A, G) Pyrimidines (C, T) A-T (2 hydrogen bonds) C-G (3 hydrogen bonds) Sugar (deoxyribose) + base = nucleoside • 1953: Rosalind Franklin (under the supervision of Maurice Wilkins): X ray diffraction Photo 51 • James Watson and Francis Crick Double Helix Model 1962 Nobel Prize (with Wilkins) • DNA coils around proteins called histones • Chromatin: DNA + 30% histones • Central Dogma of Molecular Genetics: • DNA makes RNA which makes protein • To be a genetic molecule, DNA must: replicate, store info, express info, vary by mutation The Race for the DNA Model King’s College London Cavendish Lab London Rosalind Franklin James Watson Francis Crick (X ray Diffraction Studies) Photo #51 Maurice Wilkins Nobel Prize 1962 (Double Helix Model) Semi-Conservative Replication • 1957: Meselson and Stahl labeled bacterial DNA with 15N 2 new DNA (1 old strand/1 new strand) Steps of DNA Replication • Helicases (enzymes) unwind DNA Repair errors in replicated DNA • Replication fork: where DNA opens Hydrogen bonds between base pairs break Replicon: length of DNA to be replicated • Primase (enzyme) attracts complementary bases to build a short piece called a primer • DNA polymerase (enzyme) adds more bases to primer • Ligase (enzyme) seals S-P backbone, building the new strand (Okazaki fragments) • Technology called Polymerase Chain Reaction (PCR): used DNA polymerase to rapidly produce millions of copies of a specific DNA sequence of interest Forensics: establish blood relationships, identify remains, convict criminals, evaluate those falsely accused Weakness of PCR: sensitivity Strength of PCR: works on crude samples of rare, old, minute sequences