1. The smallest units of life Chapter 3
Cells
The smallest units of life
Chapter 3

2. Cell Theory All living things are made of cells.
New cells are created from existing cells.
Cells are the basic building units of life.

3. All cells must have… a MEMBRANE to control what enters and leaves
fluid called CYTOPLASM
genetic material (DNA, RNA or both)

4. All cells (except bacteria)
2 Types of Cells
Prokaryote = no nucleus
Bacteria
Eukaryote = nucleus
All cells (except bacteria)

5. Prokaryotes bacteria No nucleus (DNA loose) Missing most organelles
Unicellular  each bacterium is 1 cell in size

6. Eukaryotes plants, animals, fungi, protozoans
Nucleus (DNA inside)
Various membrane bound organelles
Unicellular or Multicellular
(one cell) (many cells)

7. Viruses Viruses are made of genetic material and protein.
Debate exists today of whether viruses are “alive.”
Viruses depend on host cells for their survival.
8% of our human genome consists of viruses that inserted themselves in our DNA.