1. Cell History

2. Cell History All life is made of cells
Cells discovered after microscope invented
1665: Robert Hooke first observed cork (dead tree bark)
Boxes he saw reminded him of tiny rooms
He named the empty boxes “cells”
Cell History
Most likely not a picture of Robert Hooke. No known pictures have survived.
Cork cells are dead. That’s why they look empty. All that remains is the outer cell wall.
Cork is the bark of a type of oak tree. Lets zoom in…

3. Cell Theory Three Parts: 1) All organisms are made of 1 or more cells
Matthias Schleiden
Theodore Schwann
Rudolf Virchow
Cell Theory
Three Parts:
1) All organisms are made of 1 or more 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?
Rudolf Virchow
German doctor
Concluded that cells arise from preexisting cells.
Matthias Schleiden,
German botanist
Concluded that the structure of plants were composed of cell.
Theodore Schwann,
German physiologist
Extended Schleiden’s view. All life is composed of cells.
Cells have smaller parts.
So why is the cell the basic unit of life and not the smaller parts?
Where did the 1st ever cell come from?

4. Cell Diversity Shape depends upon function Typical Plant Cell Diagram
Typical Animal Cell Diagram

5. Cell Diversity B A Shape depends upon function Nerve Cell
Shape: Elongated branching
Function: Sends messages to and from brain
Advantage: Signals can travel a variety of directions B A
Could you get from City A to City B, if Interstate 80 were suddenly closed?

6. Cell Diversity Vein Shape depends upon function Nerve Cell
Shape: Elongated branching
Function: Sends messages to and from brain
Advantage: Signals can travel a variety of directions
Red Blood Cell
Shape: Disc-like
Function: Carries O2 throughout blood
Advantage: Roll through narrow veins & arteries
Vein
RBC
RBC
RBC

7. Cell Diversity Shape depends upon function Nerve Cell
Shape: Elongated branching
Function: Sends messages to and from brain
Advantage: Signals can travel a variety of directions
Red Blood Cell
Shape: Disc-like
Function: Carries O2 throughout blood
Advantage: Roll through narrow veins & arteries
Skin Cell
Shape: Flat & broad
Function: Covers and protects the body
Advantage: Overlapping layers cover more area
Skins cells act like the shingles on a roof.

8. Cell Categories
1) Prokaryote: Cells without a nucleus and other membrane-bound organelles
First cells/life on Earth (oldest fossils = ~3.5 b.y.o)
AKA: Bacteria

9. Amoeba (type of protista)
Cell Categories
Amoeba (type of protista)
Mushroom
(type of fungi)
Tree
(type of plant)
Frog
(type of animal)
2) Eukaryote: Cells with a nucleus & membrane bound organelles
More complex cells
Evolved from prokaryotes
Ex: Protists, Fungi, Plants, Animals

10. Prokaryotes vs. Eukaryotes

11. Eukaryote Evolution
Endosymbiosis Theory: Chloroplast & mitochondria were free-living organisms
Evidence: Mitochondria & chloroplast contain own DNA, replicate, contain own ribosomes
The Process
Larger cell engulfed chloroplast & mitochondria
Larger cell has an advantage
Each continued to multiply
Over time, each has become dependent on the other
Chloroplast ancestor

12. Review 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?
How do prokaryotes and eukaryotes differ?
Which organelles are associated with the endosymbiosis theory?
What evidence exists that the organelles from #8 were once free-living?