Genetic Variation in Meiosis

• What does meiosis produce?

  Four daughter cells that are genetically different from each other, called gametes.
• How many nuclear divisions does meiosis involve?

  Two.
• What number of chromosomes do the daughter cells in meiosis have?

  The haploid number.
• What does a diploid cell have?

  Two complete sets of chromosomes.
• What does a haploid cell have?


  A single set of chromosomes.
• What does meiosis result in?

  Genetic variation.
• What mechanisms in meiosis introduce genetic variation?

  Independent segregation of homologous chromosomes, and crossing over between homologous chromosomes which both occur in meiosis 1.
• What is independent segregation?


  The large number of possible combinations of chromosomes in daughter cells that could be created from when the paternal and maternal chromosomes in homologous pairs are randomly lined up at the equator and then are separated.
• How do we calculate the possible combinations of chromosomes in daughter cells?

  Using 2^n where n is the number of homologous pairs.
• What is crossing over?


  When homologous pairs line opposite each other at the equator in meiosis 1 and the chromatids are twisted around each other, creating tension and causing them to break and recombine with the other, exchanging alleles.
• What does crossing over result in?

  New combinations of alleles.
• What are gametes used in?

  Sexual reproduction.