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Genetics: DNA Structure and Analysis

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Terms in this set (20)

  • Requirements for genetic material
    Information storage, replication, expression, and variation by mutation are the four key criteria a molecule must fulfill to serve as genetic material.
  • Central dogma of molecular genetics
    Information flows from DNA to RNA to protein through transcription and translation.
  • Tetranucleotide hypothesis
    Early 20th-century idea that DNA was composed of repeating units of four nucleotides in equal amounts, leading to the belief DNA was too simple to be genetic material.
  • Griffith's transformation experiment
    Showed that a "transforming principle" from dead virulent bacteria could convert live avirulent bacteria into virulent form.
  • Avery, MacLeod, and McCarty experiment
    Identified DNA as the transforming principle by showing only DNA could transform avirulent bacteria into virulent forms after enzymatic digestion.
  • Hershey-Chase experiment
    Used bacteriophages labeled with radioactive isotopes to prove DNA, not protein, is the genetic material entering bacteria during infection.
  • Nucleotide components
    Each nucleotide consists of a pentose sugar (deoxyribose in DNA), a nitrogenous base (purines or pyrimidines), and a phosphate group.
  • Phosphodiester bond
    Covalent bond linking the 5' phosphate of one nucleotide to the 3' hydroxyl of the next, forming the sugar-phosphate backbone.
  • Watson and Crick DNA model
    DNA is a double helix with two antiparallel strands; adenine pairs with thymine via two hydrogen bonds, guanine pairs with cytosine via three.
  • Chargaff's rules
    In DNA, the amount of adenine equals thymine, and guanine equals cytosine; the (A+T)/(G+C) ratio varies among species.
  • Role of Rosalind Franklin's X-ray diffraction
    Provided critical evidence of DNA's helical structure and periodicity, supporting the double helix model.
  • Differences between DNA and RNA sugars
    DNA contains deoxyribose, while RNA contains ribose.
  • Differences in nitrogenous bases between DNA and RNA
    DNA uses thymine; RNA uses uracil instead of thymine.
  • Strandedness of DNA vs RNA
    DNA is usually double-stranded; RNA is usually single-stranded.
  • Main classes of RNA and their functions
    mRNA carries genetic info, rRNA forms ribosome structure, tRNA brings amino acids during protein synthesis.
  • RNA as genetic material in viruses
    Some viruses, like retroviruses, use RNA as genetic material and replicate via reverse transcription to DNA.
  • DNA denaturation and melting temperature (Tm)
    Denaturation separates DNA strands; Tm is the temperature where half the DNA is denatured.
  • Molecular hybridization
    Process where complementary single strands from different sources anneal; basis for techniques like FISH.
  • Electrophoresis in nucleic acid analysis
    Technique that separates DNA or RNA fragments by size using an electric field.
  • RNA world hypothesis
    Proposes RNA was the original genetic material due to its ability to store information and catalyze reactions.