Cell Biology Overview

Cell biology is the study of cells, their physiological properties, structure, the organelles they contain, interactions, and their behavior in different environments.

Prokaryotic Cells:
- No nucleus or membrane-bound organelles.
- Example: Bacteria and Archaea.
Eukaryotic Cells:
- Contain a nucleus and membrane-bound organelles.
- Example: Animal, plant, fungi, and protist cells.

Cell Membrane:
- Composed of a phospholipid bilayer; controls the movement of substances in and out of the cell.
Nucleus:
- Contains genetic material (DNA); responsible for controlling cellular activities.
Cytoplasm:
- Gel-like fluid inside the cell where organelles are suspended.
Organelles:
- Mitochondria: Powerhouse of the cell; site of ATP production.
- Ribosomes: Protein synthesis; can be free-floating or attached to the endoplasmic reticulum.
- Endoplasmic Reticulum (ER):
  - Rough ER: Studded with ribosomes; synthesizes proteins.
  - Smooth ER: Lacks ribosomes; synthesizes lipids and detoxifies chemicals.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or use in the cell.
- Lysosomes: Contains digestive enzymes to break down waste materials.
- Chloroplasts (in plant cells): Site of photosynthesis; contains chlorophyll.
- Cell Wall (in plant cells): Provides structure and protection; made of cellulose.

Mitosis:
- Process of cell division that results in two genetically identical daughter cells.
- Phases: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
Meiosis:
- Specialized cell division that reduces chromosome number by half; produces gametes (sperm and egg).
- Involves two rounds of division: Meiosis I and Meiosis II.

Cellular Respiration:
- Process of converting glucose and oxygen into energy (ATP), carbon dioxide, and water.
- Stages: Glycolysis, Krebs Cycle, and Electron Transport Chain.
Photosynthesis:
- Process by which green plants, algae, and some bacteria convert light energy into chemical energy (glucose).
- Takes place in chloroplasts; involves light-dependent and light-independent reactions.
Transport Mechanisms:
- Passive Transport: Movement of substances across cell membrane without energy (e.g., diffusion, osmosis).
- Active Transport: Movement of substances against concentration gradient using energy (e.g., sodium-potassium pump).

Cell Signaling:
- Mechanisms by which cells communicate with each other through signaling molecules (e.g., hormones, neurotransmitters).
Receptors:
- Proteins on cell surfaces or inside cells that bind to signaling molecules and initiate a response.

Understanding cellular processes is crucial for advancements in medicine, genetics, biotechnology, and environmental science.

Study of cells encompassing their properties, structure, organelles, interactions, and behaviors in various environments.

Prokaryotic Cells:
- Lack a nucleus and membrane-bound organelles; primarily found in bacteria and archaea.
Eukaryotic Cells:
- Feature a nucleus and membrane-bound organelles; examples include animal, plant, fungi, and protist cells.

Cell Membrane:
- Comprises a phospholipid bilayer that regulates the entry and exit of substances.
Nucleus:
- Houses genetic material (DNA) and orchestrates cellular activities.
Cytoplasm:
- Gel-like matrix where organelles reside.
Organelles:
- Mitochondria: Produces ATP, the cell's energy currency.
- Ribosomes: Sites of protein synthesis; can be found free in cytoplasm or bound to the endoplasmic reticulum.
- Endoplasmic Reticulum (ER):
  - Rough ER: Ribosome-studded, involved in protein synthesis.
  - Smooth ER: Lacks ribosomes, synthesizes lipids, and detoxifies harmful substances.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or intracellular use.
- Lysosomes: Contain enzymes to degrade waste and cellular debris.
- Chloroplasts (plant cells): Perform photosynthesis, converting light energy into glucose; contain chlorophyll.
- Cell Wall (plant cells): Offers structural support and protection; primarily made of cellulose.

Mitosis:
- Results in two genetically identical cells; consists of Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
Meiosis:
- Reduces chromosome number by half; essential for gamete formation (sperm and egg) through two rounds of division: Meiosis I and Meiosis II.

Cellular Respiration:
- Converts glucose and oxygen into energy (ATP), carbon dioxide, and water; stages include Glycolysis, Krebs Cycle, and Electron Transport Chain.
Photosynthesis:
- Converts light energy into chemical energy (glucose); occurs in chloroplasts with light-dependent and light-independent stages.
Transport Mechanisms:
- Passive Transport: Does not require energy; includes diffusion and osmosis.
- Active Transport: Requires energy to move substances against their concentration gradient (e.g., sodium-potassium pump).

Cell Signaling:
- Involves communication between cells through signaling molecules, including hormones and neurotransmitters.
Receptors:
- Proteins that bind to signaling molecules, triggering a response within the cell.

Essential for advancements in fields such as medicine, genetics, biotechnology, and environmental science. Understanding cellular functions underpins research and innovation in these areas.