Cell Theory
KEY CONCEPT: Cells are the basic unit of life.
Many scientists contributed to the cell theory.
– examined thin slices of cork; 1st to identify cells and
name them “cells”
•Leeuwenhoek – observed cells in greater detail by looking at
pond water; saw first living cells “animalcules”
•Schleiden – (compound microscope) – looked at plant tissue;
plants made of cells
•Schwann – (compound microscope)- looked at animal cells;
concluded all living things made of cells
•Virchow – proposed all cells come from other cells
•Hooke
The cell theory grew out of the work of
many scientists and improvements in the
microscope.
Many scientists contributed to the cell
theory.
More was learned about cells
as microscopes improved.
The cell theory grew out of the work of
many scientists and improvements in the
microscope.
Many scientists contributed to the cell
theory.
More was learned about cells
as microscopes improved.
The cell theory is a unifying
concept of biology.
• Important technological advances led to the cell theory
Better lenses were crafted to solve problems like color distortion
and poor image resolution.
Microscopes became more sturdy and easier to handle.
Photography & photomicrographs
Stains – internal cell structures take up different dyes according to
their composition.
Mounting – use of cover glass and mounting media increased
clarity.
Lighting – the electric lamp revolutionized illumination giving a
uniform field.
Early studies led to the development of the
cell theory.
•
The Cell theory has three principles.
– All organisms are made of cells.
Early studies led to the development of the
cell theory.
•
The Cell theory has three principles.
– All organisms are made of cells.
– All existing cells are produced by other living cells.
Early studies led to the development of the
cell theory.
The Cell theory has three principles.
All organisms are made of cells.
All existing cells are produced by other living cells.
The cell is the most basic unit of life.
There are two cell types: eukaryotic cells
and prokaryotic cells.
All cells share certain characteristics.
There are two cell types: eukaryotic cells
and prokaryotic cells.
All cells share certain characteristics.
Cells tend to be microscopic.
Bacterium
(colored SEM; magnification 8800x)
There are two cell types: eukaryotic cells
and prokaryotic cells.
All cells share certain characteristics.
Cells tend to be microscopic.
All cells are enclosed
cell membrane
by a membrane.
Bacterium
(colored SEM; magnification 8800x)
There are two cell types: eukaryotic cells
and prokaryotic cells.
All cells share certain characteristics.
Cells tend to be microscopic.
All cells are enclosed
cell membrane
by a membrane.
All cells are filled with
cytoplasm.
cytoplasm
Bacterium
(colored SEM; magnification 8800x)
There are two cell types: eukaryotic cells and
prokaryotic cells.
Eukaryotic cells have:
A nucleus
nucleus
A cell membrane
Cytoplasm
Membrane-bound
organelles
organelles
cell membrane
There are two cell types: eukaryotic cells and
prokaryotic cells.
Prokaryotic cells:
Do not have a nucleus.
nucleus
Have cytoplasm.
Do not have
membrane-bound organelles.
Are microscopic single-celled
organisms.
organelles
cell membrane