Overview
This lecture explains the differences between prokaryotic and eukaryotic cells, covering key structures, functions, and their relevance to health and classification of life.
Infection Example: Fungus vs. Bacteria
- Ringworm is caused by a fungus, not a worm.
- Fungal infections are treated with antifungal agents, not antibiotics.
- Antibiotics specifically target bacteria by disrupting their vital processes.
Cell Theory and Domains of Life
- Modern cell theory states all living things are made up of one or more cells.
- There are three domains: Bacteria, Archaea (both prokaryotes), and Eukarya (eukaryotes).
- Prokaryotes are always unicellular; eukaryotes may be unicellular or multicellular.
Prokaryotic vs. Eukaryotic Cells: Similarities
- Both cell types contain DNA as genetic material.
- Both have ribosomes to produce proteins.
- Both contain cytoplasm, the jelly-like cell fluid.
- Both are surrounded by a cell (plasma) membrane.
Prokaryotic vs. Eukaryotic Cells: Differences
- Prokaryotic cells are usually smaller and simpler.
- Prokaryotic cells have no nucleus; their DNA floats freely.
- Prokaryotic cells lack membrane-bound organelles.
- Eukaryotic cells have a nucleus enclosing DNA.
- Eukaryotic cells contain membrane-bound organelles (e.g., nucleus, mitochondria).
- Not all eukaryotic cells have cell walls; animal cells do not, but plant and fungal cells often do.
- Prokaryote = "no" nucleus, Eukaryote = "do" have nucleus.
Importance of Cell Type Identification
- Classifying cell types helps identify organisms (bacteria, archaea, protists, fungi, plants, animals).
- Knowing if a pathogen is prokaryotic or eukaryotic guides proper treatment.
Key Terms & Definitions
- Antibiotic — Medicine that kills or inhibits bacteria.
- Antifungal — Medicine that kills or inhibits fungi.
- Prokaryote — Unicellular organism without a nucleus or membrane-bound organelles (bacteria, archaea).
- Eukaryote — Organism with cells that have a nucleus and membrane-bound organelles (protists, plants, animals, fungi).
- Ribosome — Organelle that builds proteins.
- Cytoplasm — Jelly-like fluid inside cells.
- Cell Membrane (Plasma Membrane) — Structure regulating entry/exit of cell substances.
- Membrane-bound Organelle — Organelle surrounded by its own membrane (e.g., nucleus, mitochondria).
- Cell Wall — Rigid outer layer (not present in all cell types).
Action Items / Next Steps
- Practice comparing and contrasting prokaryotic and eukaryotic cells using vocabulary terms.
- Review the domains of life and examples of each cell type.