Lesson #15 Meiosis

• What is the primary function of meiosis in sexual reproduction?

  To transmit genetic information through cycles of meiosis and fertilization

  
• What are the similarities between meiosis and mitosis?

  • Both use a microtubule-based spindle machine
  • Both segregate condensed DNA molecules into two daughter cells
  • Both include prophase, metaphase, anaphase, and telophase
• What are the key features that distinguish meiosis from mitosis?

  • Two rounds of division (Meiosis I and Meiosis II)
  • One round of DNA replication
  • Synapsis occurs in Meiosis I
  • Crossing over occurs between homologous chromosomes

  
• How many rounds of division occur in meiosis?

  Two rounds of division
• What is synapsis in meiosis?

  Association between homologous chromosome pairs in Meiosis I

  
• What is crossing over in meiosis?

  Homologous exchange of DNA segments between non-sister chromatids

  
• When does synapsis occur during meiosis?

  During early prophase I

  
• What is the significance of chiasmata in meiosis?

  They are the sites where crossing over occurs
• How does crossing over affect genetic variation?

  It allows alleles of genes that were formerly separate to be found on the same homologue
• What happens during Meiosis I?

  • Orientation of homologous chromosomes is random
  • Independent assortment occurs
  • Sister chromatids are no longer identical due to crossing over
• What occurs during Meiosis II?

  • Occurs after an interval of variable length
  • DNA replication is suppressed
  • Resembles a mitotic division with separation of sister chromatids

  
• What do gametes develop from in animals?

  They develop directly into gametes
• How do gametes develop in plants, fungi, and protists?

  They first reproduce mitotically to increase number
• What is nondisjunction in meiosis?

  It leads to aneuploid gametes with missing or extra chromosomes
• What is a common consequence of nondisjunction?

  It is a common cause of spontaneous abortion
• What are the benefits of meiosis despite potential errors?

  • Provides genetic variation
  • Enhances adaptability of species
  • Outweighs the risks of potential errors