Cell Biology Basics

Prokaryotic Cells
- Lack a nucleus.
- Smaller and simpler (e.g., bacteria).
- Genetic material is located in the nucleoid region.
Eukaryotic Cells
- Have a nucleus.
- Larger and more complex (e.g., plant and animal cells).
- Contain membrane-bound organelles (e.g., mitochondria, endoplasmic reticulum).

Cell Membrane
- Semi-permeable barrier that controls movement in and out of the cell.
- Composed of a phospholipid bilayer with embedded proteins.
Nucleus
- Contains genetic material (DNA).
- Controls cellular activities and gene expression.
Mitochondria
- Powerhouse of the cell, site of ATP (energy) production.
- Involved in cellular respiration.
Ribosomes
- Sites of 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.
Golgi Apparatus
- Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
Lysosomes
- Contain digestive enzymes to break down waste materials and cellular debris.
Cytoskeleton
- Network of fibers providing structural support.
- Involved in cell movement and transport within the cell.

Mitosis
- Division of the nucleus resulting in two identical daughter cells.
- Phases: Prophase, Metaphase, Anaphase, Telophase.
Cytokinesis
- Division of the cytoplasm following mitosis, resulting in two separate cells.
Meiosis
- Specialized form of cell division that produces gametes (sperm and eggs).
- Reduces chromosome number by half, introducing genetic diversity.

Cells communicate through chemical signals (e.g., hormones).
Cell receptors bind to signaling molecules to initiate responses.
Types of signaling:
- Autocrine: Cell targets itself.
- Paracrine: Cell targets nearby cells.
- Endocrine: Signals travel through the bloodstream to distant cells.

Passive Transport
- Diffusion: Movement of molecules from high to low concentration.
- Osmosis: Diffusion of water across a semi-permeable membrane.
Active Transport
- Requires energy (ATP) to move substances against their concentration gradient.
- Includes pumps (e.g., sodium-potassium pump) and vesicular transport (endocytosis, exocytosis).

Prokaryotic Cells
- Lack a nucleus or membrane-bound organelles
- Simpler and smaller
- Example: Bacteria
Eukaryotic Cells
- Have a nucleus and membrane-bound organelles
- More complex and larger
- Example: Animal and plant cells

Cell Membrane
- Controls what goes in and out of a cell
- Made of a phospholipid bilayer with embedded proteins
Nucleus
- Contains DNA, which is the cell's genetic material
- Controls cellular activities and gene expression
Mitochondria
- The "powerhouse" of the cell, producing energy (ATP)
- Involved in cellular respiration
Ribosomes
- Manufacture proteins for the cell
- Can be free-floating in the cytoplasm or attached to the ER
Endoplasmic Reticulum (ER)
- Rough ER: Makes proteins, covered in ribosomes
- Smooth ER: Makes lipids, detoxifies, and lacks ribosomes
Golgi Apparatus
- Processes and packages proteins and lipids
- Prepares these molecules for secretion or use within the cell
Lysosomes
- Contain digestive enzymes to break down waste and cellular debris
Cytoskeleton
- Provides structural support for the cell
- Involved in cell movement and transport within the cell

Mitosis
- Division of the nucleus resulting in two identical daughter cells
- Four phases:
  - Prophase
  - Metaphase
  - Anaphase
  - Telophase
Cytokinesis
- Division of the cytoplasm after mitosis, leading to two separate cells
Meiosis
- Specialized cell division that produces gametes (sperm and eggs)
- Reduces the chromosome number by half, introducing genetic diversity

Cells communicate through chemical signals like hormones
Cell receptors bind to signaling molecules to trigger responses
Types of signaling:
- Autocrine: Cell targets itself
- Paracrine: Cell targets nearby cells
- Endocrine: Signals travel through the bloodstream to distant cells

Passive Transport
- Diffusion: Movement of molecules from high to low concentration
- Osmosis: Movement of water across a semi-permeable membrane
Active Transport
- Requires energy (ATP) to move substances against their concentration gradient
- Examples:
  - Pumps like the sodium-potassium pump
  - Vesicular transport (endocytosis, exocytosis)