1. Cells Cells have many different sizes, shapes, and functions
Most are microscopic
Some are large - egg cell
Some are long - nerve cell (nerve cell in giraffe leg is 2+ meters long!)
Flat cells – skin cells cover the body
Long cells – nerve cells transmit messages to different areas
Shape changers – white blood cells move through narrow openings to track down diseases.
Cells contain many small organs or organelles (“elle” = small/tiny)
Like organs in a body, they all have specific functions.
Ex: Brain controls body, nucleus in cell controls cell.

2. Prokaryotic Cells “Pro” – before, “karyo” – nucleus
Does NOT have a membrane-enclosed nucleus
Has 1 long, circular chromosome not contained within a nucleus
Does NOT have membrane-enclosed organelles
Have organelles: Cell Wall, Cell Membrane, Ribosomes, Flagella, Cytoplasm, & Chromosome
Cell size is usually small
Less complex cells
First cell on earth, 3.5 billion years ago
Bacteria is the only type of prokaryote currently living

3. Eukaryotic Cells “Eu” – true, “karyo” – nucleus
Contains a “true” nucleus – nucleus is membrane enclosed
DNA is wrapped with proteins to make chromosomes
Most organelles are membrane enclosed
Cell size is generally larger than prokaryotic cells
Complex cells
Evolved 1.5 billion years ago
Evolved from prokaryotic cells
All cells other than bacteria