Cell Biology: Cell Theory and Structure

Prokaryotic Cells
- Lack a nucleus and membrane-bound organelles.
- Smaller and simpler in structure.
- Examples: Bacteria and Archaea.
Eukaryotic Cells
- Contain a nucleus and membrane-bound organelles.
- Larger and more complex.
- Examples: Plant cells, animal cells, fungi, and protists.

Plasma Membrane
- Phospholipid bilayer that regulates the movement of substances in and out of the cell.
Nucleus
- Contains genetic material (DNA).
- Controls cell activities through gene expression.
Cytoplasm
- Jelly-like substance where organelles are suspended.
- Site of metabolic processes.
Organelles
- Mitochondria: Powerhouse of the cell; site of ATP (energy) production.
- Ribosomes: Synthesize proteins; found free in cytoplasm or attached to the endoplasmic reticulum.
- Endoplasmic Reticulum (ER):
  - Rough ER: Studded with ribosomes; involved in protein synthesis and processing.
  - Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.
- Lysosomes: Contain digestive enzymes; break down waste materials and cellular debris.
- Chloroplasts (in plant cells): Site of photosynthesis; contain chlorophyll.

Mitosis
- Process of cell division that results in two identical daughter cells.
- Stages: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
Meiosis
- Specialized form of cell division that produces gametes (sperm and eggs).
- Reduces chromosome number by half; involves two rounds of division.

Cellular Respiration
- Process of converting glucose and oxygen into ATP, carbon dioxide, and water.
- Involves glycolysis, the Krebs cycle, and the electron transport chain.
Photosynthesis
- The process by which plants, algae, and some bacteria convert light energy into chemical energy (glucose).
- Occurs in chloroplasts; involves light-dependent and light-independent reactions (Calvin cycle).

Passive Transport: Movement of substances across the membrane without energy, e.g., diffusion and osmosis.
Active Transport: Movement of substances against their concentration gradient; requires energy (ATP).

Network of protein filaments and tubules providing structural support, shape, and movement.
Composed of microfilaments, intermediate filaments, and microtubules.

All living organisms consist of one or more cells, establishing the foundation of biological life.
Cells function as the basic unit of life, organizing biological processes.
Cells originate from pre-existing cells, ensuring continuity in life.

Prokaryotic Cells:
- No nucleus or membrane-bound organelles, making them less complex.
- Smaller in size, primarily bacteria and archaea.
Eukaryotic Cells:
- Feature a nucleus and various organelles, allowing for compartmentalization.
- Larger and more complex, includes plant cells, animal cells, fungi, and protists.

Plasma Membrane:
- A phospholipid bilayer that selectively regulates the entry and exit of substances.
Nucleus:
- Houses genetic material (DNA) and regulates cell functions through gene expression.
Cytoplasm:
- A viscous fluid that contains organelles and is the site for metabolic activities.
Organelles:
- Mitochondria: Key role in energy production via ATP synthesis.
- Ribosomes: Protein synthesis site, distributed freely or attached to the endoplasmic reticulum.
- Endoplasmic Reticulum (ER):
  - Rough ER: Involved in the synthesis and processing of proteins due to ribosome presence.
  - Smooth ER: Facilitates lipid synthesis and detoxification processes.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport or secretion.
- Lysosomes: Contain enzymes for breaking down waste and cellular debris.
- Chloroplasts (in plant cells): Conduct photosynthesis and contain chlorophyll for light absorption.

Mitosis:
- Results in two identical daughter cells through stages: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
Meiosis:
- Produces gametes (sperm and eggs), reducing chromosome number by half, involving two division cycles.

Cellular Respiration:
- Converts glucose and oxygen into ATP, with byproducts of carbon dioxide and water.
- Involves glycolysis, the Krebs cycle, and the electron transport chain for energy conversion.
Photosynthesis:
- Plants, algae, and select bacteria convert light energy into glucose, occurring in chloroplasts.
- Comprises light-dependent reactions and the light-independent Calvin cycle.

Passive Transport:
- Substances move across the membrane without energy, through processes like diffusion and osmosis.
Active Transport:
- Movement of substances against a concentration gradient that necessitates energy (ATP).

A structural network of protein filaments and tubules that maintains cell shape and supports movement.
Composed of three components: microfilaments, intermediate filaments, and microtubules.