Understanding Cell Cycle and Mitosis

Sep 14, 2024

Genetics and Heredity: Cellular Reproduction

Introduction

  • Focus on genetics and hereditary concepts.
  • Two interconnected lectures:
    • Cellular division.
    • Connection to cancer development.

Cellular Reproduction

  • Dynamics of one cell becoming two.
  • Involves new terminology (e.g., chromosome, chromatin, centromere).

Cancer and Cell Growth

  • Balance between cell growth and cell death.
  • Excessive cell growth leads to cancer.
  • Excessive cell death leads to organ failure, aging effects.
  • Apoptosis (programmed cell death) is crucial for normal development.
    • Avoids webbed fingers/toes, aids brain development.

The Cell Cycle

  • Cell Cycle: Overall process of cell growth and division.
  • Mitosis: Specific phase where one cell divides into two.
  • Meiosis: Process related to sexual reproduction, forming cells with half the genetic material.

Mitosis

  • Applications of Mitosis:
    • Growth and development.
    • Repair and regeneration of tissues.
    • Asexual reproduction in plants, fungi.
  • Key Processes in Mitosis:
    • Chromosome duplication.
    • Formation of sister chromatids.

Chromosomes and DNA

  • Human cells have 46 chromosomes.
  • Chromosomes composed of chromatin (DNA + proteins).
  • Duplication results in sister chromatids joined by a centromere.
  • Different organisms have varied chromosome numbers.

Chromosomal Anomalies

  • Deviations in chromosome number often fatal.
  • Exceptions: Extra chromosome 21 (Down syndrome), extra sex chromosomes.

Haploid vs. Diploid

  • Diploid: Full set of chromosomes (46 in humans).
  • Haploid: Half the set, essential in sexual reproduction.

Phases of Mitosis

  1. Prophase:
    • Chromatin condenses into visible chromosomes.
    • Nuclear envelope disintegrates.
    • Mitotic spindle forms, attaches to centromeres.
  2. Metaphase:
    • Chromosomes align at cell's equator.
  3. Anaphase:
    • Sister chromatids pulled apart to opposite cell poles.
  4. Telophase:
    • Opposite of prophase.
    • Chromatids uncoil, nuclear envelope reforms, spindle breaks down.

Cytokinesis

  • Division of cytoplasm, final step forming two separate cells.
  • Animal Cells: Pinch cytoplasm (contractile ring).
  • Plant Cells: Form new cell plate (cell wall formation).

Conclusion

  • Understanding cell cycle and mitosis is critical for comprehension of growth, development, repair, and genetic stability.