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

Nucleus
- Controls cell activities; houses genetic material (DNA).
Mitochondria
- Powerhouse of the cell; site of ATP (energy) production through cellular respiration.
Endoplasmic Reticulum (ER)
- Rough ER: Studded with ribosomes; synthesizes proteins.
- Smooth ER: Lacks ribosomes; synthesizes lipids, detoxifies substances.
Golgi Apparatus
- Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
Lysosomes
- Contains enzymes for digestion of macromolecules; involved in waste removal.
Ribosomes
- Sites of protein synthesis; can be free in the cytoplasm or attached to the ER.
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.