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DNA Structure and Replication - General Biology

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이 집합의 용어 (21)

  • Watson & Crick Model of DNA
    DNA is a double helix with antiparallel strands held together by hydrogen bonds between complementary bases (A-T, G-C).
  • Purpose of DNA Replication
    To ensure genetic information is accurately passed to daughter cells during cell division.
  • Griffith's Transformation Experiment
    Showed that a transforming principle from dead pathogenic bacteria could genetically alter live non-pathogenic bacteria.
  • Hershey-Chase Experiment
    Used radioactive isotopes to show that DNA, not protein, is the genetic material injected by phages into bacteria.
  • Chargaff's Rules
    1. Base composition of DNA varies between species. 2. In any species, % of A = T and % of G = C.
  • Role of Rosalind Franklin
    Produced X-ray crystallographic images of DNA that enabled Watson and Crick to deduce the double helix structure.
  • Telomeres
    Special nucleotide sequences at the ends of eukaryotic chromosomes that postpone shortening during replication.
  • Telomerase
    An enzyme that lengthens telomeres in germ cells; inactive in most somatic cells but active in many cancer cells.
  • Chromatin
    Complex of DNA and histone proteins; includes euchromatin (loosely packed, active) and heterochromatin (densely packed, inactive).
  • Semi-Conservative Model of DNA Replication
    Each new DNA molecule has one old (parental) strand and one newly synthesized strand.
  • Replication Fork
    Y-shaped region where DNA strands are separated and replication occurs.
  • Key Enzymes in DNA Replication
    Helicase unwinds DNA; Primase synthesizes RNA primer; DNA polymerase adds nucleotides; Topoisomerase relieves strain; DNA ligase joins fragments.
  • Direction of DNA Synthesis
    DNA polymerase adds nucleotides only to the 3’ end, synthesizing DNA in the 5’ to 3’ direction.
  • Leading vs Lagging Strand
    Leading strand is synthesized continuously; lagging strand is synthesized discontinuously as Okazaki fragments.
  • Okazaki Fragments
    Short DNA fragments synthesized on the lagging strand during DNA replication.
  • DNA Polymerase Proofreading
    DNA polymerases proofread newly made DNA, replacing incorrect nucleotides to reduce errors.
  • Mismatch Repair
    Enzymes correct errors missed by DNA polymerase to maintain DNA integrity.
  • Nucleotide Excision Repair
    Removes and replaces damaged DNA segments caused by chemical or physical agents.
  • DNA Cloning
    Inserting DNA into plasmids to create recombinant DNA using restriction enzymes and cloning vectors.
  • Polymerase Chain Reaction (PCR)
    Technique to amplify specific DNA segments using cycles of denaturation, annealing, and extension with heat-stable DNA polymerase.
  • CRISPR-Cas9 System
    A genome editing tool using guide RNA to direct Cas9 nuclease to target DNA sequences for cutting and modification.