Lecture Notes on Mitosis

Introduction

• Observations in daily life can illustrate mitosis:
  • Healing of cuts
  • Growth of nails
  • Increase in body size from childhood to adulthood
• These processes are linked by mitosis, a type of cell division.

Importance of Mitosis

• Growth: Essential for increasing body size by making more cells.
• Repair: Replaces damaged cells (e.g., healing cuts).
• Key Characteristics:
  • Produces identical cells
  • Does not create sperm or egg cells (that is meiosis)

What Mitosis Is Not

• Not the process of making gametes (sperm or egg cells).
• Differences between mitosis and meiosis.

Mitosis and the Cell Cycle

• Cell Cycle:
  • Cells spend most time in interphase, not dividing, but growing and replicating DNA.
  • Mitosis is a short phase where actual cell division happens.

The Role of the Nucleus and DNA in Mitosis

• Nucleus: Contains the genetic material (DNA).
• DNA:
  • Must be identical in new cells.
  • Organized into chromosomes for division.

Chromosomes

• Humans have 46 chromosomes per cell nucleus.
• Chromosomes must be duplicated before mitosis.
• Interphase:
  • Duplicating DNA to prepare for mitosis.
  • Results in 46 chromosomes but 92 chromatids due to duplication.

Steps of Mitosis (PMAT)

• P for Prophase:
  • Beginning stage
  • Nucleus is present; chromosomes condense and become visible.
• M for Metaphase:
  • Chromosomes line up in the middle of the cell.
  • The nucleus disassembles.
• A for Anaphase:
  • Chromosomes move 'away' to cell poles.
  • Spindles facilitate movement.
• T for Telophase:
  • Chromosomes at opposite ends; new nuclei form.
  • End goal: two identical cells.

Cytokinesis

• Final separation into two cells by splitting the cytoplasm.
• Completes after PMAT.

Importance of Understanding Mitosis

• Understanding growth and repair processes.
• Critical for cancer research (uncontrolled mitosis).

Conclusion

• Curiosity about cell processes like mitosis is encouraged.