1. Cell
History
van Leeuwenhoek
Hooke

2. Cell History All life is made of cells
Discovered after microscope invented
1665: Robert Hooke first observed cork (dead plant bark)
Cork reminded him of tiny rooms
He named the empty boxes “cells”

3. Cell Theory Schleiden Schwann Virchow Three Parts:
1) All organisms are made of cells
2) The cell is the most basic unit of life
3) Cells come from other cells
What’s the big problem with this theory?
Schwann
Virchow

4. Cell Diversity Shape depends upon function
Nerve Shape: Elongated branching
Function: Sends messages to and from brain
Red Blood Shape: Disc-like shape prevents clogging
Function: Carries O2 throughout blood
Skin Shape: Flat & broad; layers overlap
Function: Covers and protects the body

5. Cell Categories
1) Prokaryote: Cells without a nucleus and other membrane-bound organelles
Oldest cells known (~4 billion years old)
Believed to have evolved first (oldest fossils)
AKA: Bacteria

6. 2) Eukaryote: Cells with a nucleus & membrane bound organelles
Cell Categories
2) Eukaryote: Cells with a nucleus & membrane bound organelles
More complex cells
Evolved from prokaryotes
Ex: Protists, Fungi, Plants, Animals

7. Quiz Who first identified cells? What was he/she examining?
Name the three parts to the cell theory.
Explain how the shape of a blood cell allows it to perform it’s job better.
Which category of cells contain nuclei?
Why are bacteria considered the oldest forms of life on Earth?