Lecture on Mitosis

Introduction

• Speaker: Professor Dave
• Topic: Mitosis
• Occurs during the cell cycle, facilitating cell division.

Importance of Mitosis

• Mitosis is the process of cell division creating two identical cells.
• It's happening throughout the body, enabling growth and repair.
• All somatic cells are produced by mitosis, except the first fertilized egg cell.

Phases of Mitosis

Mitosis is divided into five main phases: prophase, prometaphase, metaphase, anaphase, and telophase, followed by cytokinesis.

1. Prophase

• Chromatin condenses into chromosomes with sister chromatids connected by a centromere.
• Mitotic spindle begins to form from centrosomes and microtubules.
• Centrosomes push apart as the cytoskeleton disassembles.

2. Prometaphase

• Nuclear envelope breaks down.
• Microtubules invade the nuclear area and attach to kinetochores on centromeres.

3. Metaphase

• Chromosomes align at the metaphase plate.
• Centrosomes are at opposite poles.
• Metaphase checkpoint ensures chromatids are ready for separation.

4. Anaphase

• Shortest phase of mitosis.
• Enzyme separase cleaves cohesins, separating sister chromatids.
• Chromatids move to opposite ends as microtubules shorten and the cell elongates.

5. Telophase

• Nuclear membranes reform around two sets of chromosomes.
• Chromosomes decondense.
• Microtubules disassemble.

Cytokinesis

• Division of the cytoplasm into two separate cells.
• Cleavage furrow forms, pinching the cell into two distinct cells.

Contextual Importance

• Mitosis is crucial for replacing cells, growth, and healing.

Additional Note

• The first somatic cell arises from a fertilized egg, with gametes produced by a different process (meiosis).

Conclusion

• Mitosis is an essential biological process for cellular replication and organismal development.