Cell Division Overview

Study Notes

Cell division is the process by which a cell becomes two daughter cells
It is a fundamental process in multicellular organisms, allowing for growth, repair, and reproduction
There are two main types of cell division: mitosis and meiosis

Occurs in somatic cells (non-reproductive cells) for growth, repair, and maintenance
Results in two genetically identical daughter cells
Consists of four stages:
1. Prophase: Chromatin condenses, nuclear envelope breaks down, and spindle fibers form
2. Metaphase: Chromosomes align at the center of the cell
3. Anaphase: Sister chromatids separate and move to opposite poles
4. Telophase: Nuclear envelope reforms, and chromatin uncondenses
5. Cytokinesis: Cytoplasm divides, and the cell splits into two daughter cells

Occurs in reproductive cells (gametes: sperm and egg cells) for sexual reproduction
Results in four genetically unique daughter cells with half the number of chromosomes as the parent cell
Consists of two successive cell divisions (meiosis I and meiosis II)
Key features:
- Crossing over: Genetic recombination between homologous chromosomes
- Independent assortment: Random alignment of chromosomes during metaphase
- Random fertilization: Combination of gametes from different parents increases genetic diversity

Cell division is tightly regulated to ensure proper growth, development, and maintenance
Checkpoints and regulatory mechanisms prevent uncontrolled cell growth and division
Key regulators:
- Cyclin-dependent kinases (CDKs): Enzymes that drive the cell cycle forward
- Cyclin-dependent kinase inhibitors (CKIs): Proteins that inhibit CDK activity
- Retinoblastoma protein (Rb): A tumor suppressor that regulates the G1/S checkpoint

Cell division is essential for growth, repair, and reproduction in multicellular organisms
It involves the reproduction of cells, resulting in two daughter cells
There are two primary types of cell division: mitosis and meiosis

Meiosis occurs in reproductive cells (gametes) for sexual reproduction
It results in four genetically unique daughter cells with half the number of chromosomes as the parent cell
The process involves two successive cell divisions (meiosis I and meiosis II)
Key features of meiosis include:
Crossing over: Genetic recombination between homologous chromosomes
Independent assortment: Random alignment of chromosomes during metaphase
Random fertilization: Combination of gametes from different parents increases genetic diversity

Cell division is tightly regulated to ensure proper growth, development, and maintenance
Checkpoints and regulatory mechanisms prevent uncontrolled cell growth and division
Key regulators of cell division include:
Cyclin-dependent kinases (CDKs): Enzymes that drive the cell cycle forward
Cyclin-dependent kinase inhibitors (CKIs): Proteins that inhibit CDK activity
Retinoblastoma protein (Rb): A tumor suppressor that regulates the G1/S checkpoint