Introduction to Cells
Dragonfly Book: Chapter 7-1
Ms. McCaughan
LSHS
The Discovery of Cells

Cells were not
described until
1665……….WHY?
1.
2.
Scientists did not begin
to use microscopes
until the mid-1600’s
Most cells are too
small to see without
the microscope!
The Discovery of Cells
A. Robert Hooke (1665)
1. English Biologist
2. Observed a thin slice
of cork (plant material)
using an early
microscope
3. Saw thousands of tiny
chambers which he
called “cells”
Draw what he
saw in the box
The Discovery of Cells
B. Anton van Leeuwenhoek (1674)
1. Dutch biologist
2. Observed tiny living organisms in drops of pond water
through a simple microscope.
C. Matthias Schleiden (1838)
1. German botanist concluded all plants are made of cells
D. Theodor Schwann (1839)
1. German biologist stated all animals are made of cells
E. Rundolph Virchow (1855)
1. Proposed all cells come from existing cells
Cell Theory
1.
2.
3.
The discoveries of all of the mentioned
biologists formed a fundamental concept
in biology known as CELL THEORY
All living things are composed of cells
Cells are the basic units of structure and
function in living things
New cells are produced from existing cells
Cells have common characteristics
A. DNA

Genetic material
B. Cell Membrane

Lipid bi-layer that controls what goes into and out
of the cell
C. Ribosomes

Structures used in protein synthesis
D. Cytoplasm

E. Cytoskeleton
The interior of the cell Fibers that give cells structure
Prokaryotic Cells
A.
B.
C.
D.

“Pro” = before, “karyotic” = nucleus
At least 3.5 billion years old
Simplest and smallest cells
No nucleus (Nucleiod region in the center to hold DNA)
No specialized organelles
(Still function as living: grow, reproduce and respond to
environment)
 Examples: Bacteria and blue-green algae
Prokaryotic
Cells
Eukaryotic Cells
A.
B.
C.
D.
E.
F.
“Eu” = true, “karyotic” = nucleus
Evolved about 1.5 billion years ago
Larger and more complex than
prokaryotes
Nucleus (DNA packaged in chromosomes)
Many specialized organelles
Examples: Plants, Animals, protist & fungi
Eukaryotic Cells
Plant Cell
Animal Cell
Comparison Chart
All Cells
•Found
in living
things
•Basic unit of life
•Produced from
existing cells
Contain:
•Cell
membrane
•DNA
•Ribosomes
•Cytoplasm
•Cytoskeleton
Prokaryotes
Eukaryotes
•Older
•Newer
•Smaller
•Larger
•Simple
•Complex
•No
•Nucleus
nucleus
Nucleoid region
•No
specialized
organelles
•Examples:
bacteria, algae
•Many
specialized
organelles
•Examples:
plants, animals,
protists, fungi