Structure and Replication of DNA

Cards (35)

  • Which of the following statements about DNA replication is correct?
    Polymerase adds nucleotides to the 3’ end of a DNA strand
  • During the polymerase chain reaction (PCR) samples of DNA are repeatedly heated and cooled. Why are the samples cooled?
    To allow primers to bind to target
    sequences
  • Nucleotide contains: deoxyribose sugar, phosphate group, and nitrogen base
  • Backbone composed by: sugar phosphate, nitrogen bases, and hydrogen bonds
  • The total number of deoxyribose sugars in a fragment of DNA is DOUBLE
  • A DNA molecule replicates three times during three cell division processes. How many of the 8 resulting DNA molecules will contain the original DNA strands?
    2
  • The number of sugar molecules to bases in a nucleotide is HALF
  • Name the type of bond which links the primer to backbone
    Hydrogen bond
  • Name the chemical group found at the 5’ end of a DNA strand
    Phosphate group
  • Strand B is replicated continuously while strand A can only be replicated in fragments. Explain why the strands are replicated in different ways.
    Nucleotides can only be added to the 3’ end (of a new strand/primer) OR DNA can only be replicated from 5’ to 3’
  • there are 3 amino acids in a single dna bond
  • State the function of PCR.
    amplification of DNA
  • what happens in the first stage of PCR?
    heated 92-98, denatures DNA, breaking hydrogen bonds to separate strands
  • what happens in the second stage of PCR?
    DNA cooled to 50-65, allow primers to bind to target sequences
  • what happens in the last step of PCR?
    heated to 70-80, heat-tolerant DNA polymerase replicates DNA, two strands form
  • During replication, what bonds between the two DNA strands
    are broken.
    hydrogen
  • what are the requirements for DNA replication?
    Nucleotides, DNA polymerase, primer, template DNA, and energy.
  • what is an original DNA template?
    double helix made of two complementary strands, each strand used as a template to create new DNA molecules
  • what is DNA polymerase?
    an enzyme that adds new nucleotides to a growing strand of DNA
  • what is a primer?
    short strand of nucleotides that will bind to 3' end of template strand allowing DNA polymerase to add free DNA nucleotides
  • Explain why DNA replication must take place before a cell
    divides.
    to maintain DNA chromosome compliment
  • Give the term used to describe the unit made up of sugar,
    phosphate and base.
    nucleotide
  • Name the sugar found in a strand of DNA.
    deoxyribose
  • Describe the directional arrangement of the two strands in
    DNA.
    Have an antiparallel structure.
    With deoxyribose at 3’ end and phosphate at 5’ end of each strand.
  • During DNA replication, hydrogen bonding is broken. Name the
    enzyme which does this.
    DNA polymerase.
  • Name the type of bond which links the base of one nucleotide
    to the base of another.
    hydrogen
  • What is the first event in the process of DNA replication?
    DNA untwists and strands separate.
  • Name the 2 enzymes involved in DNA replication and state
    their functions.
    DNA polymeraseadds nucleotides to 3’ end of primer
    DNA ligasejoins fragments of DNA.
  • State the name of the molecule required to begin DNA
    replication.
    primer
  • Herring and human have the same percentage of bases,
    yet are very different organisms. Suggest a reason for this.
    new cells have identical DNA to the original.
  • State the end of the strand to which DNA
    polymerase adds nucleotides.
    3'
  • Give one practical application of PCR.
    Paternity suits / forensics / genetic sequencing.
  • The diagram shows the contents of a tube used in PCR. Describe the contents of a suitable control tube designed to show that primers are needed in the reaction.
    Test tube with DNA, DNA nucleotides, enzyme and buffer (no primers).
  • State the structural difference between the 3’ and 5’
    end of a DNA strand.
    The 3’ end of the strand contains deoxyribose (sugar) and the 5’ end contains phosphate.
  • State the term which describes the production of
    multiple copies of DNA using PCR.
    amplification