Cell Biology Basics

Cell Theory

• The cell theory states that all living things are made up of one or more cells.
• All living things are made of cells, and all cells originate from pre-existing cells.

Prokaryotic vs Eukaryotic Cells

• Prokaryotic cells lack a nucleus and other membrane-bound organelles.
• Eukaryotic cells have a nucleus and other membrane-bound organelles.

Cell Composition

• All cells are composed of four main organic molecules: carbohydrates, lipids, proteins, and nucleic acids.

Essential Cell Structures

• Almost all cells have a plasma membrane, cytoplasm, and genetic material (DNA or RNA).

Plasma Membrane

• The plasma membrane is a thin, flexible barrier that surrounds the cell.
• It's composed of a phospholipid bilayer, with hydrophilic heads facing outward and hydrophobic tails facing inward.

Organelles and Their Functions

• Mitochondria: Powerhouse of the cell, responsible for ATP production through cellular respiration.
• Ribosomes: Sites of protein synthesis, responsible for translating mRNA into proteins.
• Rough Endoplasmic Reticulum (RER): Network of interconnected membranes studded with ribosomes, involved in protein synthesis and modification.
• Smooth Endoplasmic Reticulum (SER): Network of interconnected membranes without ribosomes, involved in lipid synthesis, detoxification, and calcium storage.
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport within or outside the cell.
• Lysosomes: Contain enzymes that break down cellular waste products and foreign materials.
• Peroxisomes: Contain enzymes that break down fatty acids and toxic substances.
• Cytoskeleton: Network of protein filaments that provides structural support, facilitates movement, and helps with cell division.
• Centrioles: Involved in the formation of microtubules and spindle fibers during cell division.
• Nucleus: Contains the cell's genetic material (DNA), controls cellular activities.
• Nucleolus: Site of ribosome synthesis within the nucleus.
• Cell wall: Rigid outer layer that provides structural support and protection, found in plant cells.
• Chloroplasts: Site of photosynthesis in plant cells, containing chlorophyll pigment.
• Central Vacuole: Large, fluid-filled sac in plant cells, responsible for storage, turgor pressure, and waste disposal.
• Motor proteins: Move along cytoskeletal tracks to transport vesicles containing molecules.
• Vesicles: Small, membrane-bound sacs that transport molecules within the cell.

Plant vs Animal Cells

• Plant cells have cell walls, chloroplasts, and central vacuoles.
• Animal cells lack these structures.

Additional Terms

• Organelle: Specialized structure within a cell that performs a specific function.
• Phospholipid bilayer: The double layer of phospholipids that forms the plasma membrane.
• Cytoplasm: The gel-like substance that fills the cell, excluding the nucleus.
• ECF: Extracellular fluid, the fluid outside of the cell.
• ICF: Intracellular fluid, the fluid inside of the cell.
• IF: Intermediate filaments, a type of cytoskeletal filament.