Final answer:
Meiosis I and Meiosis II comprise the processes that produce haploid gametes through two rounds of cell division. In Meiosis I, unique features like homologous chromosome pairing and crossing-over occur. Meiosis II resembles mitosis, with the separation of sister chromatids leading to the formation of four unique haploid cells.
Step-by-step explanation:
Key Features of Meiosis I and Meiosis II
Meiosis is a two-part cell division process that produces haploid gametes. There are distinct key features that are specific to Meiosis I and Meiosis II.
Meiosis I
- Prophase I: Homologous chromosomes pair up, crossing-over occurs, and the nuclear envelope begins to break down.
- Prometaphase I: Spindle fibers attach to the kinetochores of chromosomes.
- Metaphase I: Homologous chromosomes line up at the metaphase plate in tetrads.
- Anaphase I: Homologous chromosomes, now consisting of sister chromatids, are pulled to opposite poles.
- Telophase I: The nuclear envelope may reform, and the cell prepares to divide into two cells.
Meiosis II
- Prophase II: Chromosomes condense again, and the nuclear envelope breaks down if necessary.
- Prometaphase II: New spindle fibers attach to kinetochores of sister chromatids.
- Metaphase II: Chromosomes line up at the metaphase plate, similar to mitosis.
- Anaphase II: Sister chromatids are pulled apart to opposite ends of the cell.
- Telophase II: A nuclear envelope forms around each set of chromatids, now individual chromosomes.
Unlike mitosis, meiosis results in four unique haploid cells due to the reduction division in Meiosis I and the separation of sister chromatids in Meiosis II.