Introduction to Cell Biology

Definition: Study of cells, their physiological properties, structure, organelles, interactions, and behavior.
Significance: Fundamental to understanding life processes and biological systems.

Prokaryotic Cells
- Lack a nucleus and membrane-bound organelles.
- Examples: Bacteria and Archaea.
- Generally smaller and simpler.
Eukaryotic Cells
- Contain a nucleus and membrane-bound organelles.
- Examples: Animal cells, plant cells, fungi, and protists.
- Larger and more complex.

Cell Membrane:
- Semi-permeable barrier that regulates entry and exit of substances.
Nucleus:
- Contains genetic material (DNA).
- Controls cell activities and reproduction.
Mitochondria:
- Powerhouse of the cell, site of ATP (energy) production.
Ribosomes:
- Sites of protein synthesis.
Endoplasmic Reticulum (ER):
- Rough ER: Studded with ribosomes; involved in protein synthesis and modification.
- Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.
Golgi Apparatus:
- Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
Lysosomes:
- Contain digestive enzymes; involved in waste disposal and recycling of cellular components.
Chloroplasts (in plant cells):
- Site of photosynthesis; contain chlorophyll.
Cytoskeleton:
- Network of fibers providing structural support, shape, and transport within the cell.

Cell Division:
- Mitosis: Process of cell division for growth and repair, resulting in two identical daughter cells.
- Meiosis: Specialized division for gamete formation, resulting in four genetically varied cells.
Cellular Respiration:
- Process of converting glucose and oxygen into energy (ATP), carbon dioxide, and water.
Photosynthesis (in plants):
- Conversion of light energy into chemical energy (glucose) using carbon dioxide and water.

Signal Transduction:
- Process by which cells respond to external signals (hormones, neurotransmitters) through receptors and intracellular pathways.
Cell Adhesion:
- Interaction between cells through adhesion molecules (e.g., cadherins, integrins) to form tissues.

Homeostasis:
- Maintenance of a stable internal environment within cells.
Cell Theory:
- All living organisms are composed of cells.
- Cells are the basic unit of life.
- All cells arise from pre-existing cells.

Medicine: Understanding diseases at the cellular level aids in the development of treatments.
Biotechnology: Genetic engineering, stem cell research, and drug development.
Ecology: Studying cellular interactions in ecosystems.

Study of cells encompasses their properties, structure, organelles, interactions, and behavior.
Understanding cell biology is essential for comprehending life processes and biological systems.

Prokaryotic Cells:
- Characterized by the absence of a nucleus and membrane-bound organelles.
- Examples include bacteria and archaea, generally smaller and simpler than eukaryotic cells.
Eukaryotic Cells:
- Feature a nucleus and membrane-bound organelles.
- Examples include animal cells, plant cells, fungi, and protists, which are larger and more complex.

Cell Membrane:
- Acts as a semi-permeable barrier regulating substance movement in and out of the cell.
Nucleus:
- Houses genetic material (DNA) and governs cell activities and reproduction.
Mitochondria:
- Known as the cell's powerhouse; key site for ATP (energy) production.
Ribosomes:
- Responsible for protein synthesis, can be free in cytoplasm or attached to the endoplasmic reticulum.
Endoplasmic Reticulum (ER):
- Rough ER: Studded with ribosomes; functions in protein synthesis and modification.
- Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification processes.
Golgi Apparatus:
- Modifies, sorts, and packages proteins and lipids for secretion or internal use.
Lysosomes:
- Contain digestive enzymes for waste disposal and recycling raw materials within the cell.
Chloroplasts (specific to plant cells):
- Site of photosynthesis, containing chlorophyll for absorbing light energy.
Cytoskeleton:
- A network of fibers providing structural support, shape, and facilitating transport within the cell.

Cell Division:
- Mitosis: Cell division process for growth and repair, producing two identical daughter cells.
- Meiosis: Special division for gamete formation, resulting in four genetically diverse cells.
Cellular Respiration:
- Converts glucose and oxygen into energy (ATP), producing carbon dioxide and water as byproducts.
Photosynthesis (occurs in plants):
- Process of converting light energy into chemical energy (glucose) using carbon dioxide and water.

Signal Transduction:
- Cells react to external signals (hormones, neurotransmitters) through receptors and intracellular signaling pathways.
Cell Adhesion:
- Cells interact via adhesion molecules (like cadherins and integrins) to form tissues.

Homeostasis:
- The ability to maintain a stable internal environment within cells.
Cell Theory:
- Asserts that all living organisms are composed of cells, which serve as the basic unit of life, and all cells arise from pre-existing cells.

Medicine:
- Enhances understanding of diseases at a cellular level, influencing treatment development.
Biotechnology:
- Encompasses genetic engineering, stem cell research, and drug discovery.
Ecology:
- Analyzes cellular interactions within ecosystems to understand complex biological networks.