1. Prokaryotes & EukaryotesBy
Diana L. Duckworth
Rustburg High School
Campbell County

2. Features in common All cells are surrounded by a plasma membrane
Inside membrane is semifluid substance called cytosol (cytoplasm)
All cells contain chromosomes carrying genes in form of DNA
All cells contain ribosomes (site of protein manufacture)

3. Prokaryotic Cells DNA found in region called nucleoid
No membrane isolates DNA from cytosol
No specialized organelles in cytosol
May have cilia or flagella for locomotion
Cell wall – rigid structure outside membrane
May have a capsule around cell wall

5. Eukaryotic Cell DNA combines with histones to form chromosomes
Inside a nuclear membrane (DNA isolated from cytoplasm)
Well defined nucleus
Numerous specialized organelles in cytoplasm
Many internal membranes
Much larger than prokaryotes

6. Plant Cell Animal Cell chloroplast Cell wall vacuole
vacuole
Plant Cell
Animal Cell

7. Why be small?
Cells must obtain nutrients & expel wastes across cell membranes
As size decreases, surface area increases.
Amount of surface area/volume increases.
Cell functions more efficiently.

8. Cell or Plasma Membranes
Phospholipid Bilayer
Hydrophobic lipid tails orient away from water in cytoplasm & outside cell
Hydrophyllic heads contain phosphate groups
Lipid tails either saturated or unsaturated

9. Electron Micrograph of Cell Membranes
8 nm thick
Cell membranes

10. Membrane Proteins Ends of proteins are hydrophyllic
Center is hydrophobic
Integral proteins go through membrane
Peripheral proteins are only on surface
Proteins have many functions (later)

11. Other Components of Membranes
Carbohydrate chains attached to proteins (glycoproteins) or lipids (glycolipids)
(blood types)
In animal cells cholesterol molecules are embedded in membrane
Keeps membrane fluid at low temps (homeostasis)
Membranes are fluid
Phospholipids move 10
million times/second
Some proteins move;
others don’t

12. Membranes are “sided” Selective permeability
Allow some things in and not others
Vacuoles expell some waste & proteins to outside
Vacuole membrane must merge with cell membrane
Inside of vacuole is same as outside of cell