Cell Biology Study Notes for PCMB 11 and 12

Cell Biology Study Notes for PCMB 11 and 12

Key Concepts

• Cell Theory

  • All living organisms are composed of cells.
  • Cells are the basic unit of life.
  • All cells arise from pre-existing cells.

• Cell Structure

  • Prokaryotic Cells: Lack a nucleus; DNA is in the nucleoid region.
    • Examples: Bacteria and Archaea.
  • Eukaryotic Cells: Have a nucleus; more complex structures.
    • Features: Membrane-bound organelles (mitochondria, endoplasmic reticulum).

• Cell Membrane

  • Composed of phospholipid bilayer.
  • Proteins embedded for transport and signaling.
  • Semi-permeable; regulates entry and exit of substances.

Organelles and Their Functions

1. Nucleus

   • Controls cell activities; houses genetic material (DNA).

2. Mitochondria

   • Powerhouse of the cell; site of ATP (energy) production through cellular respiration.

3. Endoplasmic Reticulum (ER)

   • Rough ER: Studded with ribosomes; synthesizes proteins.
   • Smooth ER: Lacks ribosomes; synthesizes lipids, detoxifies substances.

4. Golgi Apparatus

   • Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.

5. Lysosomes

   • Contains enzymes for digestion of macromolecules; involved in waste removal.

6. Ribosomes

   • Sites of protein synthesis; can be free in the cytoplasm or attached to the ER.

7. Cytoskeleton

   • Structure and support for the cell; involved in intracellular transport and cell division.
   • Composed of microfilaments, intermediate filaments, and microtubules.

Cell Division

• Mitosis

  • Process of somatic cell division; results in two identical daughter cells.
  • Stages: Prophase, Metaphase, Anaphase, Telophase.

• Meiosis

  • Process of gamete formation; results in four genetically diverse daughter cells.
  • Two stages: Meiosis I and Meiosis II.

Cellular Metabolism

• Metabolism Overview

  • The sum of all chemical reactions in a cell; includes anabolic (building) and catabolic (breaking down) pathways.

• Ex. of Metabolic Pathways

  • Glycolysis: Breakdown of glucose to produce energy.
  • Krebs Cycle: Produces electron carriers for the electron transport chain.

Cellular Communication

• Signal Transduction Pathways

  • Mechanisms by which cells respond to signals from the environment.
  • Involves receptors, second messengers, and cellular responses.

• Types of Cell Signaling

  • Autocrine: Cells respond to signals they secrete.
  • Paracrine: Signals act on neighboring cells.
  • Endocrine: Hormonal signals travel through the bloodstream.

Additional Concepts

• Cell Cycle Regulation

  • Checkpoints ensure proper progression; dysfunction can lead to cancer.

• Apoptosis

  • Programmed cell death; crucial for development and maintaining cellular health.

• Stem Cells

  • Undifferentiated cells with the potential to develop into various cell types; important for regeneration and repair.

These notes encapsulate essential components of cell biology relevant to PCMB 11 and 12, emphasizing structure, function, processes, and regulation within cells.

Cell Theory

• All living organisms are made of cells.
• Cells are the fundamental unit of life.
• Cells arise from pre-existing cells.

Cell Types

• Prokaryotic cells: Lack a nucleus; DNA is in the nucleoid; examples include bacteria and archaea.
• Eukaryotic cells: Possess a membrane-bound nucleus and complex organelles; examples include animal and plant cells.

Cell Membrane

• Phospholipid bilayer structure.
• Embedded proteins facilitate transport and signaling.
• Selectively permeable, controlling substance passage.

Organelles & Functions

• Nucleus: Houses DNA; controls cell activities.
• Mitochondria: ATP production via cellular respiration; the "powerhouse" of the cell.
• Endoplasmic Reticulum (ER):
  • Rough ER: Protein synthesis (ribosome-studded).
  • Smooth ER: Lipid synthesis and detoxification.
• Golgi Apparatus: Protein and lipid modification, sorting, and packaging.
• Lysosomes: Contain digestive enzymes; involved in waste breakdown.
• Ribosomes: Protein synthesis; found free in cytoplasm or bound to ER.
• Cytoskeleton: Provides structural support; aids in intracellular transport and cell division; composed of microtubules, microfilaments, and intermediate filaments.

Cell Division

• Mitosis: Somatic cell division; produces two genetically identical daughter cells. Stages include prophase, metaphase, anaphase, and telophase.
• Meiosis: Gamete (sex cell) formation; yields four genetically diverse daughter cells. Involves two divisions: Meiosis I and Meiosis II.

Cellular Metabolism

• Metabolism: All chemical reactions within a cell; encompasses anabolic (building) and catabolic (breaking down) pathways.
• Examples: Glycolysis (glucose breakdown); Krebs cycle (generates electron carriers for the electron transport chain).

Cellular Communication

• Signal Transduction: Mechanisms enabling cellular responses to environmental signals; involves receptors, second messengers, and downstream effects.
• Signal Types:
  • Autocrine: Cell responds to its own signals.
  • Paracrine: Signals affect nearby cells.
  • Endocrine: Hormones travel via the bloodstream.

Additional Concepts

• Cell Cycle Regulation: Checkpoints ensure orderly progression; malfunctions can cause cancer.
• Apoptosis: Programmed cell death; essential for development and maintaining cellular health.
• Stem Cells: Undifferentiated cells capable of differentiating into various cell types; crucial for tissue repair and regeneration.