Lecture on Mitosis

Introduction to Cloning and Cell Division

Fictional idea of human cloning for daily tasks
Reality: Human cloning not possible
- Cells, however, can clone themselves continuously
- Essential for growth, development, healing, and survival

Definition: The process of cell division allowing one cell to split into two genetically identical cells
Functions:
- Growth (e.g., from baby to child)
- Repair (e.g., healing cuts, replacing damaged liver cells)
- Can also lead to unregulated growth (e.g., tumors)
Occurs approximately 10 quadrillion times in a human lifetime

Humans have trillions of cells, each containing DNA in the nucleus
Chromosomes: DNA organized into 46 chromosomes in 23 pairs
- Diploid cells: 46 chromosomes (somatic cells)
- Haploid cells: 23 chromosomes (sex cells, formed by meiosis)
Mitosis focuses on diploid cells

Interphase
- Cells are in a state of growth and normal functioning
- DNA exists as chromatin, loosely coiled
- Centrosomes duplicate
Prophase
- Chromatin condenses into visible chromosomes
- Chromatids form: X-shaped structures where two identical copies join at the centromere
- Nuclear envelope disintegrates
- Centrosomes move to opposite cell ends
Metaphase
- Chromosomes attach to microtubules at centromeres
- Chromosomes align in the cell center
- Motor proteins (e.g., dynein) aid in chromosome alignment
Anaphase
- Chromatids pulled apart into individual chromosomes
- Chromosomes migrate to opposite ends of the cell
Telophase
- Nuclear membranes reform around each set of chromosomes
- Chromosomes relax back into chromatin
- Cleavage furrow forms, preparing for cell split
Cytokinesis
- Final separation into two genetically identical daughter cells