Meiosis

• What are the stages of cell division discussed in the video?

  Meiosis and mitosis
• What is the outcome of cell division by meiosis?

  Four haploid gametes
• Why is it important that gametes are haploid cells?

  They fuse to form a diploid zygote
• Where does cell division by meiosis occur?

  In sex organs
• What type of cells are produced by meiosis?

  Gametes, such as sperm and eggs
• What is a key difference between mitosis and meiosis?

  Meiosis produces genetically different cells
• What are homologous chromosomes?

  Chromosome pairs from each parent
• What do homologous chromosomes have in common?

  They have the same genes
• What can differ between homologous chromosomes?

  The alleles inherited from each parent
• What is crossing over in meiosis?

  Exchange of DNA between chromatids
• What are the points where chromatids are joined called?

  Chiasmata
• What are recombinant chromosomes?

  Chromosomes that have exchanged DNA
• How does crossing over contribute to genetic variation?

  It allows alleles to be exchanged
• What are the key ideas about meiosis and genetic variation?

  • Meiosis produces four genetically different gametes
  • Gametes are haploid, allowing diploid zygote formation
  • Crossing over exchanges DNA between homologous chromosomes
  • Alleles can be different between homologous chromosomes
• What is the significance of homologous chromosomes in meiosis?

  • They contain the same genes
  • They can have different alleles
  • They undergo crossing over during meiosis
  • They contribute to genetic diversity in offspring
• What are the stages of meiosis that will be covered in the next video?

  • Prophase I
  • Metaphase I
  • Anaphase I
  • Telophase I
  • Prophase II
  • Metaphase II
  • Anaphase II
  • Telophase II
• What type of reproduction produces genetically dissimilar offspring?

  Sexual reproduction
• What process is required for sexual reproduction?

  Meiosis
• What are the special reproductive cells called?

  Gametes
• What happens during fertilization?

  Two gametes fuse to produce a zygote
• What is the chromosome number in each gamete?

  Haploid
• What is a diploid cell?

  A cell with the full number of chromosomes
• What are the stages of meiosis?

  1. Prophase I
  2. Metaphase I
  3. Anaphase I
  4. Telophase I
  5. Prophase II
  6. Metaphase II
  7. Anaphase II
  8. Telophase II
• What occurs during Prophase I of meiosis?

  Chromosomes shorten, fatten, and form bivalents
• What is crossing over?

  Swapping of DNA sections between chromatids
• What forms at points called chiasmata?

  Chromatids wrap around each other
• What happens during Metaphase I?

  Bivalents arrange randomly on the cell equator
• What is the role of spindle fibers in Anaphase I?

  They pull homologous chromosomes to opposite poles
• What occurs during Telophase I?

  Nuclear envelopes reform and cytokinesis occurs
• What happens during Prophase II?

  Nuclear envelopes break down and spindle fibers form
• What is the arrangement of chromosomes during Metaphase II?

  Chromosomes align on the equator of each cell
• What occurs during Anaphase II?

  Chromatids are pulled to opposite poles
• What is formed at the end of Telophase II?

  A tetrad of four haploid cells
• What is the role of interphase in meiosis?

  The cell rests until the next meiotic division
• How does meiosis increase genetic variation?

  • Crossing over during Prophase I
  • Random distribution of chromosomes
  • Random mutation
  • Random variation from fertilization
• What is the significance of crossing over during Prophase I?

  It introduces genetic variation by shuffling alleles
• How many crosses over occur on average per chromosomal pair?

  Two or three crosses over
• What happens at chiasmata during crossing over?

  Chromatids can swap sections of DNA
• What is the result of crossing over in terms of alleles?

  New combinations of alleles on chromatids
• What is the overall outcome of meiosis?

  • Four haploid cells
  • Genetic variation introduced
  • Essential for sexual reproduction