Cell Biology Overview

Prokaryotic Cells:
- Lack a nucleus and membrane-bound organelles.
- Example: Bacteria and Archaea.
Eukaryotic Cells:
- Have a nucleus and membrane-bound organelles.
- Example: Animal, Plant, Fungi, and Protist cells.

Plasma Membrane:
- Semi-permeable barrier that regulates the movement of substances in and out of the cell.
Cytoplasm:
- Jelly-like fluid inside the cell where organelles are located.
Nucleus:
- Contains the cell's genetic material (DNA) and controls cellular activities.
Mitochondria:
- Powerhouse of the cell; site of ATP (energy) production.
Ribosomes:
- Sites of protein synthesis; can be free-floating or attached to the endoplasmic reticulum.
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 delivery to other organelles.
Lysosomes:
- Contain digestive enzymes to break down waste materials and cellular debris.
Cytoskeleton:
- Network of fibers that provide structure, shape, and movement to the cell.

Mitosis:
- Process by which a eukaryotic cell divides to produce two identical daughter cells.
- Stages: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
Meiosis:
- Specialized form of cell division that produces gametes (sperm and eggs).
- Involves two rounds of division (Meiosis I and II) resulting in four non-identical daughter cells.

Cellular Respiration:
- Process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.
- Stages: Glycolysis, Krebs Cycle, Electron Transport Chain.
Photosynthesis (in plant cells):
- Process by which plants convert light energy into chemical energy (glucose) using carbon dioxide and water.
- Occurs in chloroplasts; involves light-dependent and light-independent reactions (Calvin Cycle).

Cells communicate through signaling pathways involving:
- Receptors: Proteins on the cell surface that bind to signaling molecules (ligands).
- Signal Transduction: Series of molecular events and reactions that lead to a cellular response.
- Types of Signaling: Autocrine, Paracrine, Endocrine, and Juxtacrine signaling.

Passive Transport: Movement of molecules across the membrane without energy (e.g., diffusion, osmosis).
Active Transport: Movement of molecules against their concentration gradient requiring energy (e.g., sodium-potassium pump).

Cell cycle is regulated by proteins called cyclins and cyclin-dependent kinases (CDKs).
Checkpoints ensure proper cell division and DNA integrity. Major checkpoints: G1, G2, and M phase.

Undifferentiated cells with the potential to develop into different cell types.
Types:
- Embryonic Stem Cells: Can differentiate into any cell type.
- Adult Stem Cells: Limited to differentiating into a narrower range of cell types.

Prokaryotic Cells:
- Do not possess a nucleus or organelles with membranes.
- Examples include Bacteria and Archaea.
Eukaryotic Cells:
- Contain a nucleus and membrane-bound organelles.
- Examples include Animal cells, Plant cells, Fungi, and Protists.

Plasma Membrane:
- A semi-permeable layer regulating substance movement.
Cytoplasm:
- Gel-like fluid housing organelles within the cell.
Nucleus:
- Houses genetic material (DNA) and oversees cell functions.
Mitochondria:
- Known as the cell's powerhouse; responsible for ATP production.
Ribosomes:
- Sites of protein synthesis; can exist freely or on the endoplasmic reticulum.
Endoplasmic Reticulum (ER):
- Rough ER: Has ribosomes; involved in protein synthesis.
- Smooth ER: Lacks ribosomes; focuses on lipid synthesis and detoxification.
Golgi Apparatus:
- Modifies, sorts, and packages proteins and lipids for transport.
Lysosomes:
- Contain enzymes for digesting waste and cellular debris.
Cytoskeleton:
- A network of fibers providing the cell with structure and shape.

Mitosis:
- Eukaryotic cell division producing two identical daughter cells.
- Stages include Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
Meiosis:
- Specialized division creating gametes, resulting in four non-identical cells through two division rounds (Meiosis I and II).

Cellular Respiration:
- Converts glucose and oxygen into ATP, producing carbon dioxide and water.
- Involves Glycolysis, Krebs Cycle, and Electron Transport Chain.
Photosynthesis (in plants):
- Converts light energy into glucose using carbon dioxide and water.
- Takes place in chloroplasts, with light-dependent and light-independent phases (Calvin Cycle).

Cellular signaling involves:
- Receptors: Surface proteins that bind to ligands.
- Signal Transduction: A series of reactions leading to a cellular response.
- Types of Signaling: Autocrine, Paracrine, Endocrine, and Juxtacrine signaling.

Passive Transport:
- Occurs without energy, involving diffusion and osmosis.
Active Transport:
- Requires energy to move molecules against their gradient, exemplified by the sodium-potassium pump.

Undifferentiated cells capable of forming various cell types.
Types:
- Embryonic Stem Cells: Can differentiate into any cell type.
- Adult Stem Cells: Have a limited ability to differentiate.