Meiosis and Mitosis

Mitosis

• Definition: Mitosis is the process of cell division that results in two genetically identical daughter cells from a single parent cell.

• Phases:

  1. Prophase

     • Chromatin condenses into chromosomes

     • Nuclear envelope breaks down

     • Mitotic spindle begins to form

  2. Metaphase

     • Chromosomes align along the metaphase plate

  3. Anaphase

     • Sister chromatids are pulled apart to opposite poles

  4. Telophase

     • Nuclear envelope re-forms around each set of chromosomes

     • Chromosomes begin to de-condense

• Cytokinesis: Division of the cytoplasm, resulting in two separate cells.

Meiosis

• Definition: Meiosis is a specialized form of cell division that reduces the chromosome number by half, resulting in four genetically diverse gametes (sperm or eggs).

• Phases:

  1. Meiosis I:

     • Prophase I: Homologous chromosomes pair and exchange genetic material (crossing over).

     • Metaphase I: Paired homologous chromosomes align at the metaphase plate.

     • Anaphase I: Homologous chromosomes are pulled apart to opposite poles.

     • Telophase I: Nuclear envelope may reform; cytokinesis follows, resulting in two haploid cells.

  2. Meiosis II: Similar to mitosis, resulting in separation of sister chromatids.

     • Prophase II

     • Metaphase II

     • Anaphase II

     • Telophase II: Final products are four genetically diverse haploid cells.

Key Differences Between Mitosis and Meiosis

• Mitosis

  • Produces 2 identical cells

  • Asexual reproduction

  • Occurs in somatic (body) cells

• Meiosis

  • Produces 4 genetically diverse cells

  • Sexual reproduction

  • Occurs in germ cells (gametes)

Importance

• Mitosis is crucial for growth, development, and tissue repair.

• Meiosis ensures genetic diversity and is essential for reproduction.

Summary

• Understanding the processes of mitosis and meiosis is essential for grasping fundamental biological principles, including how organisms grow, reproduce, and evolve.

9. Meiosis II: Similar to mitosis, resulting in separation of sister chromatids.

• Prophase II: The nuclear envelope breaks down if it reformed during telophase I, and the spindle apparatus forms in each haploid cell.

• Metaphase II: Chromosomes align along the metaphase plate in each haploid cell.

• Anaphase II: Sister chromatids are pulled apart and move toward opposite poles of the cell.

• Telophase II: Nuclear envelope reforms around each set of chromosomes, and cytokinesis occurs, resulting in four genetically diverse haploid cells.

Interphase is the longest phase of the cell cycle, during which the cell grows and prepares for division. It consists of three stages: G1 Phase (cell growth and normal functions), S Phase (DNA synthesis and replication), and G2 Phase (preparation for mitosis). Interphase is crucial for the proper duplication of the cell's genetic material and organelles, ensuring that the daughter cells receive the necessary components for functionality after division.