B. Types of Cells and Organelles
➢ Invention of electron microscopes allowed scientists to figure out the exact functions of cells
➢ Prokaryotic cells
- Only in domains Bacteria and Archaea
- Smaller
- Simpler
- Circular DNA
■ In nucleoid region
■ NO NUCLEUS - Cell wall
■ Made up of peptidoglycans that surround a lipid layer called the plasma membrane - Filled with semi-fluid cytosol
- Have ribosomes
- Can have flagella
■ Long projections used for motility - May have a thick capsule outside their cell wall to give them extra protection
- No membrane-bound organelles
➢ Eukaryotic cells - More complex
- Organized into smaller structures called organelles
- DNA in nucleus bounded by a membranous nuclear envelope
- Cytoplasm between plasma membrane and nucleus