Meiosis

• What is meiosis?

  A form of nuclear division
• What is the result of meiosis?

  Production of haploid cells from diploid cells
• What type of cells does meiosis produce?

  Gametes
• How does meiosis differ from mitosis?

  Meiosis has two divisions, mitosis has one
• What are the stages of meiosis?

  • Meiosis I
  • Prophase I
  • Metaphase I
  • Anaphase I
  • Telophase I
  • Meiosis II
  • Prophase II
  • Metaphase II
  • Anaphase II
  • Telophase II
• What happens during prophase I of meiosis?

  DNA condenses into visible chromosomes
• What is a bivalent?

  A pair of homologous chromosomes
• What is crossing over in prophase I?

  Exchange of alleles between non-sister chromatids
• What is the chiasma?

  The point where crossing over occurs
• What happens during metaphase I?

  Bivalents line up along the spindle equator
• What is independent assortment?

  Random positioning of maternal and paternal chromosomes
• How does anaphase I differ from anaphase II?

  Homologous pairs separate in anaphase I
• What occurs during telophase I?

  Nuclear envelopes form around chromosomes
• What is cytokinesis?

  Division of the cytoplasm
• How does cytokinesis differ in plant and animal cells?

  Animal cells form a cleavage furrow; plant cells form a cell plate
• What is the end product of cytokinesis in meiosis I?

  Two haploid cells
• What happens in meiosis II?

  It resembles mitosis without DNA replication
• What occurs during prophase II?

  Nuclear envelope breaks down and chromosomes condense
• What happens during anaphase II?

  Centromeres divide and chromatids are pulled apart
• What is the result of telophase II?

  Nuclear membranes form around chromosomes
• What is the significance of meiosis?

  It increases genetic diversity in offspring
• How does crossing over contribute to genetic diversity?

  It exchanges alleles between non-sister chromatids
• What is the formula for calculating combinations of chromosomes?

  $2^n$
• How many combinations of chromosomes are possible in humans?

  8,324,608 combinations
• What is random fusion of gametes?

  Any male gamete can fuse with any female gamete
• Why is genetic variation important in sexual reproduction?

  It enhances adaptability and survival of species
• What are the mechanisms that increase genetic diversity in meiosis?

  • Crossing over
  • Independent assortment
  • Random fusion of gametes
• Where does crossing over occur?

  Prophase 1
• Where does independent segregation occur?

  Metaphase 1 and Metaphase 2