Understanding the Mitotic Cell Cycle

Aug 16, 2024

Detailed Mitotic Cell Cycle

Overview

  • Focus on the detailed stages of the mitotic cell cycle.
  • Builds on introductory concepts covered in previous videos.

Interphase

  • Newly Divided Cell: Undergoes growth and DNA replication.
  • Sub-stages of Interphase:
    • G1 Phase:
      • Increase in organelles (e.g., mitochondria, endoplasmic reticulum).
      • Size of the cell increases due to absorption of water and increase in cytoplasm volume.
      • Mature cells can perform specific functions (e.g., neurons send impulses, muscle cells move, white blood cells protect against infections).
      • Duration as a mature cell varies (e.g., skin cells a day, others indefinitely).
      • External signals can trigger continuation in the cell cycle.
    • S Phase:
      • DNA replication occurs, doubling the amount of DNA.
    • G2 Phase:
      • Correction of DNA replication errors to avoid mutations.
      • Increase in microtubule production for spindle fibers.

Mitosis (M Phase)

Prophase

  • Early Prophase:
    • Chromatin present.
    • Nuclear membrane intact.
  • End of Prophase:
    • Nuclear membrane disappears.
    • Chromatin condenses into visible sister chromatids.
    • Centrioles move to opposite poles.

Metaphase

  • Sister chromatids line up along the cell equator (or metaphase plate).
  • Spindle fibers attach to centromeres, ensuring equal separation.

Anaphase

  • Spindle fibers shorten.
  • Sister chromatids pulled apart, now individual chromatids.
  • Chromatids move to opposite poles, showing inertia of pull.

Telophase

  • Chromatids reach opposite poles.
  • Nuclear membrane reforms.
  • Chromatids uncoil, forming two nuclei.

Cytokinesis

  • Cell division occurs, producing two genetically identical cells.
  • Different processes in plant and animal cells (details in another video).

Cell Cycle Overview

  • Circular representation showing progression:
    • G1 Phase: Cell growth and organelle increase.
    • S Phase: DNA replication.
    • G2 Phase: Growth and error correction.
    • M Phase: Mitosis and cytokinesis.
  • Cells spend most time in interphase, particularly G1 and G2.
  • Mitosis and cytokinesis are relatively quick processes.

This comprehensive understanding of the mitotic cell cycle provides essential context for cellular growth, replication, and division, forming the foundation for further study into cellular biology.