Meiosis

• What is meiosis?

  A type of cell division producing variation
• How many nuclear divisions occur in meiosis?

  Two nuclear divisions
• What type of cells does meiosis produce?

  Genetically different daughter cells
• What is the term for cells with one set of chromosomes?

  Haploid cells
• What does a diploid cell contain?

  Two copies of each chromosome
• How does meiosis differ from mitosis in terms of genetic variation?

  Meiosis introduces genetic variation, mitosis does not
• What are the two mechanisms that introduce variation in meiosis?

  Independent segregation and crossing over
• When do independent segregation and crossing over occur?

  During meiosis I
• What is independent segregation?

  Homologous chromosomes align randomly at the equator
• What does the term "homologous pair" refer to?

  Two chromosomes with the same genes
• What is the formula to calculate the number of possible combinations of chromosomes in gametes?

  $2^n$, where n is homologous pairs
• What happens during crossing over in meiosis?

  Chromatids exchange segments, creating new alleles
• What is the result of crossing over?

  New combinations of alleles in gametes
• How does meiosis produce haploid cells?

  By dividing a diploid parent cell twice
• How does the number of divisions in meiosis compare to mitosis?

  Meiosis has two divisions, mitosis has one
• What is the significance of meiosis in terms of genetic variation?

  It introduces genetic diversity in offspring
• What is the notation for diploid cells?

  2n
• What should you look for in a lifecycle diagram to identify meiosis?

  Where diploid cells become haploid cells
• Why might labeling gametes in a lifecycle diagram be misleading?

  Gametes can be formed by mitosis in some organisms
• Why are identical twins genetically identical?

  They originate from the same fertilized egg
• What are the key differences between meiosis and mitosis?

  • Meiosis has two nuclear divisions; mitosis has one.
  • Meiosis produces haploid cells; mitosis produces diploid cells.
  • Meiosis introduces genetic variation; mitosis produces identical cells.
• What are the two main processes that introduce genetic variation during meiosis?

  1. Independent segregation of homologous chromosomes
  2. Crossing over between homologous chromosomes
• How does fertilization contribute to genetic variation?

  • Random fusion of sperm and egg
  • Results in $2^n$ squared combinations