1.1 + 1.2 - Structure and Replication of DNA

Cards (49)

  • A?
    phosphate
  • B?
    deoxyribose sugar
  • C?
    base
  • How is the sugar and phosphate bonded in DNA structure?
    strong covalent bond
  • How are the bases held together in DNA structure?
    weak hydrogen bond
  • Leading strand runs from 5’ to 3’
  • Lagging strand runs from 3’ to 5’
  • DNA can be described as antiparallel
  • Define DNA structure?
    a double stranded helix with anti parallel strands
  • The base sequence of DNA forms the genetic code
  • Adenine bonds to thymine
  • Cytosine bonds to guanine
  • What is a prokaryote?
    organisms that do not have a membrane bound nucleus (bacterial cells)
  • What is a eukaryote?
    organisms that have a membrane bound nucleus (animal, plant, fungal)
  • How is DNA arranged in prokaryotes ?
    • one circular chromosome
    • smaller circular plasmids to contain extra genes
  • How is DNA arranged in eukaryotes?
    • linear chromosomes in the nucleus packaged with histones to prevent tangling
    • circular chromosomes in mitochondria and chloroplasts
    • yeast also has plasmids
  • define dna replication ?
    process where DNA makes an identical copy of itself
  • dna replication always precedes mitosis
  • What 5 things are required for dna replication?
    DNA template
    enzymes (DNA polymerase)
    ATP
    DNA nucleotides
    Primers
  • what is the function of a primer?
    to initiate DNA replication
  • what is a primer?
    a short strand of nucleotides which binds to the 3’ end of the template DNA strand
  • What is the first stage of DNA replication?
    double helix is unwound by the enzyme helicase
  • stage 2 of DNA replication ?
    hydrogen bonds break between bases to form 2 template strands and a replication fork is formed
  • A?
    leading strand
  • B?
    lagging strand
  • What direction does DNA polymerase add DNA nucleotides in?
    3’ to 5’
  • the leading strand of DNA is replicated continuously
  • The lagging strand of DNA is replicated in fragments
  • why is the lagging strand replicated in fragments?
    DNA nucleotides must be added from the 3’ end
  • What happens during stage 3 of DNA replication?
    primers initiate DNA replication by binding to the 3’ end of the leading strand and at several sites of the lagging strand
  • What happens during stage 4 of DNA replication?
    DNA polymerase adds free DNA nucleotides continuously to the 3’ end of the lead strand in fragments to the 3’ end of the lag strand
  • what happens during stage 5 of dna replication?
    fragments of DNA in lag strand joined together by ligase
  • what is PCR (Polymerase chain reaction)?
    a laboratory technique used to amplify DNA using complimentary primers for specific target sequences
  • What apparatus is used in PCR?
    Thermocycler
  • What are the 3 stages of PCR?
    Denaturation, annealing, extension
  • stage 1 of PCR?
    DNA is heated between 92 and 98 °C to separate the strands
  • stage 2 of PCR?
    DNA is cooled to between 50 and 65 °C to allow primer to bind to target sequences
  • stage 3 of PCR?
    DNA is heated to between 70 and 80 °C for heat-tolerant DNA polymerase to replicate the region of DNA
  • A?
    DNA denaturation
  • B?
    primer annealing