chromosome mutations

• Who is the presenter of the A Level Biology video on chromosome mutations?

  1. Stroke
• What are chromosome mutations?

  Changes in the number of chromosomes
• What process causes chromosome mutations?

  Nondisjunction in meiosis
• What is nondisjunction?

  Failure of chromosomes to separate equally
• In which phases of meiosis can nondisjunction occur?

  Meiosis 1 and Meiosis 2
• What are the two types of effects of nondisjunction?

  Polyploidy and aneuploidy
• What does polyploidy mean?

  Many sets of chromosomes
• What happens to gametes in polyploidy?

  They can become triploid or tetraploid
• Why is polyploidy fatal in humans?

  It prevents successful fetal development
• What is the result of nondisjunction in meiosis 1 for polyploidy?

  All chromosomes fail to separate equally
• What is the result of meiosis 2 after nondisjunction in polyploidy?

  Diploid gametes are produced
• What happens when a diploid gamete fuses with a haploid gamete?

  It results in a triploid zygote
• What is aneuploidy?

  Change in the number of one chromosome
• How does nondisjunction affect gametes in aneuploidy?

  It results in gametes with extra or missing chromosomes
• What does n minus 1 indicate in gametes?

  Missing one chromosome
• What does n plus 1 indicate in gametes?

  Having one extra chromosome
• What happens when n plus 1 gametes fuse with normal gametes?

  It results in a diploid zygote with an extra chromosome
• What happens when n minus 1 gametes fuse with normal gametes?

  It results in a diploid zygote missing one chromosome
• Can nondisjunction occur in meiosis 2?

  Yes, it can occur in meiosis 2
• What is the outcome of nondisjunction in meiosis 2?

  It can produce n minus 1 and n plus 1 gametes
• What are the key differences between polyploidy and aneuploidy?

  • Polyploidy:
  • Affects all chromosomes
  • Results in multiple sets of chromosomes
  • Common in plants, fatal in humans
  • Aneuploidy:
  • Affects only one chromosome
  • Results in extra or missing chromosomes
  • Associated with conditions like Down syndrome
• How does nondisjunction lead to different types of chromosome mutations?

  • Nondisjunction in meiosis 1:
  • All chromosomes fail to separate
  • Leads to polyploidy
  • Nondisjunction in meiosis 2:
  • Only some chromatids fail to separate
  • Leads to aneuploidy