Overview
This lecture explains the process of mitosis, its role in growth and repair, the steps it involves, and its relation to cancer and genetics.
Importance of Mitosis
- Mitosis is the process of cell division for most body cells.
- It is essential for growth, allowing organisms to increase in size by producing more cells.
- Mitosis repairs damaged tissues by replacing lost or damaged cells with identical ones.
- Mitosis creates identical daughter cells, necessary for maintaining tissue function.
Mitosis vs. Meiosis
- Mitosis produces body (somatic) cells, not sperm or egg cells.
- Meiosis is the separate process that creates sperm and egg cells.
DNA, Chromosomes, and the Nucleus
- The nucleus is the organelle that holds DNA, the cell's genetic information.
- DNA is organized into condensed units called chromosomes.
- Human body cells typically have 46 chromosomes in their nuclei.
- Before mitosis, DNA is duplicated during the interphase stage of the cell cycle.
Cell Cycle and Chromosome Duplication
- Cells spend most of their time in interphase, growing and duplicating DNA.
- When chromosomes duplicate, chromatids double but chromosome number (by centromeres) stays the same.
- After duplication, there are still 46 chromosomes but now 92 chromatids.
Stages of Mitosis (PMAT)
- Prophase: Chromosomes condense and become visible; nucleus is still present.
- Metaphase: Chromosomes align in the middle of the cell; nucleus is gone.
- Anaphase: Chromosomes are pulled away to opposite poles by spindle fibers.
- Telophase: Chromosomes arrive at poles and new nuclei form on each side.
- Cytokinesis follows mitosis, splitting the cytoplasm to create two separate cells.
Mitosis and Cancer
- Cancer results from uncontrolled cell growth, meaning mitosis occurs without regulation.
Key Terms & Definitions
- Mitosis — cell division process producing identical body cells.
- Meiosis — cell division process making sperm or egg cells.
- Nucleus — cell organelle containing genetic material.
- Chromosome — condensed DNA and protein unit in the nucleus.
- Interphase — cell cycle stage for growth and DNA replication.
- Chromatid — one of two identical halves of a duplicated chromosome.
- Spindle fibers — structures that move chromosomes during mitosis.
- Cytokinesis — division of the cytoplasm to form two cells.
Action Items / Next Steps
- Review stages of mitosis and the PMAT acronym.
- Watch suggested clips on the cell cycle and chromosome counting for deeper understanding.