1. Structure & Function of Cells

2. Cell Theory The cell is the basic unit of living things
All organisms are made of cells
Cells come only from other cells
(left to right) Euglena and E. coli shown on top

3. Microscopes: Visualizing Cells
Compound Light Microscope
First compound microscope made by Hans & Zacharias Janssen (circa 1595)
Objective lens
Has 2 main lenses: eyepiece and ocular lens
Eyepiece

4. Microscopes: Visualizing Cells
Today’s compound light microscope; same concept with 2 lenses
Objective lenses vary in magnification power

5. Microscopes: Visualizing Cells
Resolving power is the most important factor of a microscope’s ability to view small objects
Limited by diffraction
Lower diffraction =
higher resolution
Resolving power: its ability to distinguish the separateness of two objects that are close together
Diffraction: scattering of light as it passes through the lens; reduced diffraction increases resolution

6. Microscopes: Visualizing Cells
Adding an oil immersion to light microscopes resolves objects 0.2 μm

7. Microscopes: Visualizing Cells
Transmission Electron Microscope (TEM)
Oil immersion resolves objects to μm
Can “see” objects 1000x smaller than light microscope

8. Microscopes: Visualizing Cells
Scanning Electron Microscopes (SEM)

9. Types of Cells Prokaryotic (bacteria) Eukaryotic (plant & animal)
Both can be between 5 and 50 micrometers (µm)

10. Prokaryotic Cells Have Lack
Cell wall (with peptidoglycan, NOT cellulose)
Cell membrane
Ribosomes
Nuclear area w/ circular loop chromosomes (nucleoid)
Often have cilia or flagella
Mesosome?
Lack
Membrane-bound organelles
True nucleus

11. Cell Parts and Functions
Mesosome (Prokaryotic only)
Invaginations of the plasma membrane
Exist only during preparation with chemical fixation (for electron microscopy)
Damage during chemical fixation?

12. Eukaryotic Cells Unicellular Multicellular protists Animal Plant Fungi
Unique structures (centriole, lysosomes, more mitochondria)
Plant
Unique structures: cell wall (w/ cellulose), large vacuole & plastids
Fungi
Cell wall made of chitin