Cell Theory
Prokaryotes and Eukaryotes
First Observations of Cells
• The invention of the microscope made it
possible for people to discover and learn
about cells.
Robert Hooke
One of the first people to observe cells was
English scientist and inventor Robert Hooke
who built his own compound microscope
and used it to look at thin slices of cork.
Anton van Leeuwenhoek
Leeuwenhoek was a businessman
who liked to make microscopes in
his spare time. He used them to
look at pond water, and scrapings
from his teeth. He found many tiny
moving organisms which he named
animalcules.
All plants
are made
of cells!
The Cell Theory
All
animals
are made
of cells!
Matthias Schleiden
Theodor Schwan
Inspired by the work of Hooke and
Leuwenhoek other scientists began to
use microscopes to study cells. Over
time, they developed the cell theory.
New cells are
formed only
from cells
that already
exist
Rudolf Virchow
The Cell Theory
• The cell theory states the following:
1. All living things are composed of cells.
2. Cells are the basic unit of structure and
function in living things.
3. All cells are produced from other cells.
CELLS
The basic unit of life
Every living thing is made up of one
or more cells!
TWO KINDS OF CELLS
1. PROKARYOTES
2. EUKARYOTES
Common Features of ALL cells:
• Cell Membrane
Common Features of ALL cells:
• Cell Membrane
• Cytoplasm
Common Features of ALL cells:
• Cell Membrane
• Cytoplasm
• DNA
Common Features of ALL cells:
• Cell Membrane
• Cytoplasm
• DNA
• Ribosomes
PROKARYOTES
1.
2.
3.
4.
All single celled organisms
Do not have a nucleus
All have a cell wall.
DNA is in a single circular ring, or loop in
the center of the cell.
EUKARYOTES
1. Can be single or multicellular
2. Has a nucleus which houses the cells DNA.
3. Contains many smaller parts called
organelles which each have a certain job in
the cell.
4. DNA is packaged into structures called
chromosomes.
TWO KINDS OF CELLS
1. PROKARYOTES
2. EUKARYOTES