1. Cells Chapter 6-1

2. What is a Cell? Cells are the basic individual units of life
All organisms are made of cells
Organisms can be either unicellular or multicellular
Most cells cannot be seen without magnification

3. Microscope development increased our understanding of cells.
1665 Robert Hooke first used the term “cell” (oak bark)
1683: Aton Van Leeuwenhoek observed organisms in pond water using a light microscope that had been fitted with high powered lenses (called them animalcules)
: Schleiden and Schwann observed cells in every plant and animal cell they examined. This led to the development of the CELL THEORY.

4. Cell Theory A Fundamental Concept of Biology
All living things are composed of one or more cells
Cells are basic units of structure and function in living things
New cells are produced from existing cells

5. Technology & Science
Compound Light Microscope magnifies images 1000x their actual size (good for bacterium or larger organisms/structures)
Electron microscopes (1940’s) using magnets that direct a beam of electrons
Transmission Electron Microscope (TEM)
magnifies images 500,000x explores internal structure of cell
Scanning electron microscopes (SEM) Explores surface of cell and gives a 3D image
Scanning tunneling microscope (STM)
Uses charged probe and can magnify live specimens

6. Technology & Science

7. The Microscope
Arm
Light Source

8. Discovery of Cell

9. Cell Diversity Surrounded by cell (plasma) membrane
All cells have 3 characteristics in common
Surrounded by cell (plasma) membrane
Contain DNA (stores genetic information)
Contain cytoplasm

10. Two Categories of Cells
Depends on whether or not cell contains a nucleus
Nucleus
Large membrane-enclosed structure
Contains cell’s genetic material (DNA)
Controls cell activities
“karyon” = “kernel” or nucleus
“eu” = true
“pro” = before

11. Two Categories of Cells
Eukaryotes
Prokaryotes
Cells that contain nucleus
Cells that don’t contain nucleus

12. Prokaryotes

13. Prokaryotes Generally smaller than eukaryotes
Have genetic material NOT contained in nucleus
3. Less complex than eukaryotes
4. No membrane bound organelles
5. Bacteria are prokaryotes

14. E.Coli

15. Streptococcus mutans
Helicobacter
Bacillus anthracis

16. Eukaryotes Larger than prokaryotes More Complex
Contain many internal structures (organelles)
Highly specialized
Genetic material contained inside nucleus, separated from rest of cell
Great variety of eukaryotes
Single-celled organisms (amoeba)
Large multicellular organisms (plants, animals, fungi, protists)