Cell Division Overview

Cell Division Overview

• 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

Mitosis

• 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

Meiosis

• 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

Regulation of Cell Division

• 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 Overview

• 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

Mitosis

• Mitosis occurs in somatic cells for growth, repair, and maintenance
• It results in two genetically identical daughter cells
• The process consists of four stages:

Prophase

• Chromatin condenses
• Nuclear envelope breaks down
• Spindle fibers form

Metaphase

• Chromosomes align at the center of the cell

Anaphase

• Sister chromatids separate and move to opposite poles

Telophase

• Nuclear envelope reforms
• Chromatin uncondenses

Cytokinesis

• Cytoplasm divides
• The cell splits into two daughter cells

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

Regulation of Cell Division

• 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