DNA, Genetics, Replication

  1. How is genetic variation achieved through meiosis? 2 ways.
    • Independent assortment
    • Crossing over
  2. What is independent assortment?
    • Various combinations of chromosomes are arranged
    • During meiosis 1
    • Homologous chromosomes line up in pairs
    • Arrangement of pairs is random -> division into the daughter cells is random
  3. What happens during crossing over?
    • Pairs of chromosomes line up and exchange some of their genetic material.
    • One chromosome may swap places with the same part of its homologous pair leading to a different combination of alleles on the gene
  4. What are the stages of meiosis?
    • Meiosis 1 - homologous chromosomes pair up, crossing over at the chiasmata may take place
    • Cell divides, each daughter cell contains one chromosome from each homologous pair
    • Meiosis 2 - chromatids of each chromosome are separated 4 haploid daughter cells produced
  5. What happens during a substitution mutation?
    A nucleotide base is replaced with another
  6. What happens during a insertion mutation?
    • An extra nucleotide base is inserted into the sequence
    • Causes ‘frameshift’ -> all the subsequent bases are shifted down 1 place relative to the twin DNA strand
  7. What happens during a deletion mutation?
    • Absence of a nucleotide
    • Causing ‘frameshift’ -> all the subsequent bases are shifted back 1 place relative to the twin DNA strand
  8. Why may a DNA mutation be harmful?
    • May result in change in order of bases
    • Changes amino acid(s) coded for
    • Final tertiary protein + its active site is deformed -> cannot fulfil function
Card Set
DNA, Genetics, Replication
The genetics and DNA make-up of organisms, including replication and mutations.