Topic 1 and 2 Notes (1)

Meiosis and Genetic Diversity

• End Product of Mitosis: Produces two genetically identical diploid daughter cells (2n).

• Genetics: Study of heredity and hereditary variation; traits are transmitted via genes from parents to offspring.

• Reproduction Types:

  • Asexual: Clonal offspring via mitosis; variations arise from mutations.

  • Sexual: Offspring have unique gene combinations from two parents, enhancing genetic diversity.

• Chromosomes:

  • Homologous Chromosomes: Paired chromosomes from each parent with the same genetic information.

  • Karyotype: Visual display of chromosomes arranged in pairs.

  • Somatic Cells: Diploid cells (2n); example: humans (46 chromosomes).

  • Gametic Cells: Haploid cells (n); example: gametes (23 chromosomes).

• Life Cycle: Sequence of reproductive stages; fertilization and meiosis alternate in sexual reproduction, creating diploid zygotes.

• Meiosis: Cell division that produces four genetically unique haploid gametes (n); involves two rounds of division (Meiosis I and II).

• Key Events in Meiosis:

  • Prophase I: Crossing over occurs.

  • Metaphase I: Tetrads align; independent orientation happens.

  • Anaphase I: Homologous pairs separate.

  • Meiosis II: Results in four unique haploid cells.

• Genetic Variation Sources:

  • Crossing Over: Exchanges genetic material.

  • Independent Assortment: Random orientation of chromosomes.

  • Random Fertilization: Enhances diversity by mixing alleles.

• Importance: Meiosis with fertilization promotes genetic diversity, crucial for adaptation and evolution.