Overview
This lecture introduces modern cell theory, compares prokaryotic and eukaryotic cells, and explains the structure and function of key organelles found in animal and plant cells.
The Modern Cell Theory
- The cell is the smallest living unit in all organisms.
- All living things are made of one or more cells (unicellular or multicellular).
- All cells come from pre-existing cells.
Types of Cells: Prokaryotes vs. Eukaryotes
- Prokaryotes (bacteria, archaea) have no nucleus or membrane-bound organelles.
- Eukaryotes (plants, animals, fungi, protists) have a nucleus and membrane-bound organelles.
- Both cell types have genetic material, cytoplasm, ribosomes, and cell membranes.
Basic Cell Structures Shared by All Cells
- The cell membrane (plasma membrane) is selectively permeable, maintaining homeostasis.
- Cytoplasm is the jelly-like material surrounding internal structures.
- Ribosomes make proteins and are found in both prokaryotes and eukaryotes.
- The cytoskeleton provides structural support and helps with cell movement.
Eukaryotic Cell Organelles and Their Functions
- Nucleus: contains DNA and controls cell activities; includes nucleolus for ribosome production.
- Endoplasmic Reticulum (ER): processes and transports molecules; rough ER has ribosomes for protein production, smooth ER is involved in detoxification and lipid production.
- Golgi Apparatus: modifies, sorts, and packages molecules for delivery inside or outside the cell.
- Mitochondria: generate ATP energy through cellular respiration using glucose and oxygen.
- Vesicles: transport materials between ER, Golgi apparatus, and other locations.
Differences Between Animal and Plant Cells
- Plant cells have chloroplasts for photosynthesis (make glucose using light energy).
- Plant cells have a large central vacuole for storage; animal cells have smaller vacuoles.
- Plant cells have a cell wall for additional protection and shape; animal cells do not.
Key Terms & Definitions
- Cell Theory — foundational principles stating cells are the basic unit of life, all living things are made of cells, and cells arise from existing cells.
- Prokaryote — a cell without a nucleus or membrane-bound organelles (e.g., bacteria).
- Eukaryote — a cell with a nucleus and membrane-bound organelles (e.g., plants, animals).
- Organelle — specialized structure within a cell that performs a specific function.
- Ribosome — small structure that synthesizes proteins.
- Nucleus — membrane-bound structure holding genetic material in eukaryotes.
- Endoplasmic Reticulum (ER) — network for protein and lipid processing and transport.
- Golgi Apparatus — organelle for modifying, sorting, and packaging proteins and lipids.
- Mitochondria — organelle producing ATP energy via cellular respiration.
- Chloroplast — organelle in plant cells for photosynthesis.
- Vacuole — storage sac inside cells; large in plants.
- Cell Wall — rigid layer outside plant cells for support.
Action Items / Next Steps
- Review and compare organelles and their functions in prokaryotic and eukaryotic cells.
- Research additional eukaryote organelles for deeper understanding.