Overview
This lecture covers the fundamental concepts of cell division, including the main types, key processes, and their biological significance.
Types of Cell Division
- There are two main types of cell division: mitosis and meiosis.
- Mitosis results in two genetically identical daughter cells.
- Meiosis produces four genetically diverse gametes, each with half the number of chromosomes.
The Cell Cycle
- The cell cycle includes interphase (G1, S, G2) and the mitotic (M) phase.
- Interphase is when the cell grows and DNA is replicated.
- The mitotic phase consists of karyokinesis (nuclear division) and cytokinesis (cytoplasm division).
Stages of Mitosis
- Mitosis includes prophase, metaphase, anaphase, and telophase.
- Prophase: Chromosomes condense and spindle fibers form.
- Metaphase: Chromosomes align at the cell's equator.
- Anaphase: Sister chromatids are pulled apart to opposite poles.
- Telophase: Nuclear membranes reform and chromosomes decondense.
Stages of Meiosis
- Meiosis has two rounds: meiosis I and meiosis II.
- Meiosis I separates homologous chromosomes; meiosis II separates sister chromatids.
- Crossing over during prophase I increases genetic variation.
Importance of Cell Division
- Cell division is essential for growth, repair, and reproduction.
- Errors in cell division can result in genetic disorders or cancer.
Key Terms & Definitions
- Mitosis — Division of a cell's nucleus producing genetically identical cells.
- Meiosis — Division producing gametes with half the chromosome number.
- Interphase — Cell cycle phase of growth and DNA replication.
- Chromatid — Each of two identical halves of a duplicated chromosome.
- Cytokinesis — Division of the cytoplasm after nuclear division.
- Crossing Over — Exchange of genetic material between homologous chromosomes during meiosis.
Action Items / Next Steps
- Review diagrams of mitosis and meiosis stages.
- Complete assigned reading on cell division in your textbook.
- Practice labeling phases of the cell cycle and their key events.