Mitosis Lecture Notes

Overview of Mitosis

• Mitosis is a process of cell division essential for:
  • Regeneration of body parts
  • Separation of nuclear chromosomes into two identical daughter nuclei

Phases of Mitosis

• Mitosis is divided into four key phases:
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
• An additional phase, Cytokinesis, occurs after nuclear division.

Interphase

• Before entering mitosis, the cell undergoes a growth and rest period called Interphase.
• In this phase, genetic material increases.

Detailed Phases of Mitosis

Prophase

• Chromatin condenses to form chromosomes (short and thick).
• Each chromosome consists of two sister chromatids joined at the centromere.
• The nucleolus disappears, and the nuclear membrane breaks down.
• Centrosomes move to opposite poles, forming a spindle between them.

Metaphase

• Microtubules of the spindle interact with chromosomes.
• Chromosomes align along the equatorial plate (middle of the cell).
• Sister chromatids are held together at the centromere by kinetochores.

Anaphase

• Sister chromatids separate at the kinetochore.
• Daughter chromosomes move toward opposite poles as microtubules shorten.
• Anaphase is complete when chromosomes are fully separated into two sets.

Telophase

• Daughter chromosomes arrive at the poles.
• Chromatin begins to decondense.
• Nuclei and nucleoli reform, and nuclear membrane reformation is triggered.

Cytokinesis

• Cytokinesis is the division of the cytoplasm.
• In animals, a cleavage furrow forms in the plasma membrane, deepening to divide the cytoplasm into two daughter cells.
• In plants, a cell plate forms at the center, growing outward to meet existing walls, leading to two daughter cells.

Summary

• Mitosis is crucial for cell division, involving four phases: Prophase, Metaphase, Anaphase, and Telophase.
• Key processes include chromatin condensation, chromosome alignment, sister chromatid separation, and reformation of nuclei and cytoplasm division.