Overview
This lecture covers the basics of cell theory, the differences between prokaryotic and eukaryotic cells, and the main functions of major cell organelles.
Modern Cell Theory
- The cell is the smallest living unit in all organisms.
- All living things are made up of one or more cells.
- All cells come from pre-existing cells.
Prokaryotes vs. Eukaryotes
- Prokaryotes include bacteria and archaea; they have no nucleus or membrane-bound organelles.
- Eukaryotes include plants, animals, fungi, and protists; they have a nucleus and membrane-bound organelles.
- Both prokaryotes and eukaryotes contain genetic material, cytoplasm, ribosomes, and a cell membrane.
Major Cell Structures and Organelles
- The cell (plasma) membrane is selectively permeable and maintains homeostasis.
- Cytoplasm is a jelly-like substance surrounding internal cell structures; found in all cells.
- Cytoskeleton is a network of fibers providing support and aiding movement.
- Ribosomes (not membrane bound) make proteins and are found in all cells.
- Nucleus (in eukaryotes) stores genetic material (DNA) and controls cell activities.
- The nucleolus (inside the nucleus) produces ribosomes.
- Endoplasmic reticulum (ER) processes and transports molecules; rough ER has ribosomes and handles protein production, smooth ER is involved in detoxification and lipid production.
- Golgi apparatus modifies, sorts, and packages molecules for transport or secretion.
- Mitochondria produce ATP energy from glucose and oxygen via cellular respiration.
- Chloroplasts (in plant cells) perform photosynthesis to make glucose.
- Vacuoles store materials; plant cells have a large central vacuole, animal cells have several small vacuoles.
- Plant cells have a cell wall for additional protection and shape.
Key Terms & Definitions
- Cell Theory — the principle that all living things are made of cells, the cell is the smallest living unit, and all cells come from existing cells.
- Prokaryote — a cell without a nucleus or membrane-bound organelles.
- Eukaryote — a cell with a nucleus and membrane-bound organelles.
- Organelle — specialized cell structure with a specific function.
- Ribosome — organelle that assembles proteins.
- Nucleus — organelle that contains DNA and controls cell functions.
- Mitochondria — organelle producing cellular energy (ATP).
- Chloroplast — plant organelle for photosynthesis.
- Cell Membrane — barrier controlling entry and exit of substances.
- Cytoskeleton — internal cell framework for support and movement.
Action Items / Next Steps
- Review key differences between prokaryotic and eukaryotic cells.
- Learn additional cell organelles not covered in this overview.
- Watch videos on the cell membrane and cytoskeleton for deeper understanding.