1. CHAPTER 6 - CELLS
Section 6.1 & 6.2

2. Importance of cells
An organism’s basic unit of structure & function is the cell
Everything we do occurs fundamentally at the cellular level
Thinking
Moving
Maintaining homeostasis
Cells discovered by Robert Hooke in 1665

3. Studying Cells How do we understand cells if we can’t see them?
Microscopes allow us to see the inner workings of cells
Two main types of Microscopes
Light Microscope (LM) – 1665-present
Electron Microscope (EM) – 1950’s-present

4. Light Microscopes
Allow us to see plant & animal cells and the nucleus.
Can also see bacteria cells.
Light passes through the specimen and lenses, bends the light to magnify the image.
Magnification: ratio of an object’s image to its real size (max. about 1,000x)
Resolution: measure of the clarity of the image (max. about 200nm – size of bacteria)

6. Electron Microscopes
Rapidly advance our understanding of cells because we could see subcellular structures
Focuses a beam of electrons through the specimen
Two types:
Scanning electron microscope (SEM)
Gives a 3D image of the surface of the specimen
Transmission electron microscope (TEM)
Used to study internal stux – gives a cross section

7. Advantages & Disadvantages
Light Microscopes
Advantage: Can study living organisms
Disadvantage: Can’t see organelles in detail
Electron Microscopes
Advantage: Can see organelles in detail
Disadvantage: Specimens are killed in preparation process (not for living tissues)

8. Cell Fractionation
Goal: take cells apart and separate the major organelles from one another
Process:
Centrifuge spins test tubes at various speeds
Cell components separate by size and density
Result:
Bulk quantity of cellular organelles to study composition and function

9. Section 6.2 Two types of cells
Prokaryotic found in Domain _______ & _______
Eukaryotic found in Domain _______
What 4 Kingdoms contain organisms with Eukaryotic cells?
1. Animal
2. Plant
3. Protist
4. Fungi

10. Similarities & Differences
All Cells contain:
Plasma membrane made up of a __________
Phospholipid bilayer
Cytosol (cytoplasm)
DNA
Ribosomes
Differences:
Eukaryotic cells contain membrane bound organelles and the DNA is contained in the nucleus.

11. Prokaryotic cells: DNA located in nucleoid region
Prefix: pro means “before”
Suffix: karyon means “kernel” (nucleus)
No membrane bound organelles in cytoplasm
Smaller & simpler
Cilia and flagella for locomotion
Some have cell wall surrounding plasma membrane

12. Prokaryotic cells

13. Cell Size Cellular metabolism sets a limit on how large a cell can get
The cell needs to bring in oxygen & nutrients and needs to get rid of waste
Cell needs to maintain a high surface area to volume ratio to exchange the materials it needs to
Larger organisms do not have larger cells just more of them (we have trillions of cells!)

14. Surface area to volume ratio

15. Plasma membrane

16. Eukaryotic cells Contain membrane bound organelles
Larger than prokaryotic cells and more complex
Animal & Plant cells
Draw a diagram of an animal and a plant cell