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Discovery and study of cells
Unit 2 part1
Packet 4
Cell biology pioneers
Robert Hooke (1665)
Examined cork under a simple
microscope…described what
he saw as “little rooms”
(cellulae, Latin)
Anton van Leeuwenhoek (1674)
Also used rudimentary microscope to examine many
things…blood, pond water, scrapings of plaque from
teeth.
Described what he saw as animicules…the first
descriptions of bacteria and protists.
Light Microscopes
Magnification vs. Resolution
 Magnification increase in size
 Resolution measure of
clarity
Electron Microscopes
 Use a beam of
electrons instead of
light
 SEM and TEM
Transmission Electron Microscope
(TEM): for studying the internal structure of cells
Spinach Cell Chloroplast
Scanning Electron Microscope (SEM):
for studying the surfaces of cells
Cells are covered in metal, then reflect electrons.
SEM
A View of the Cell
We’ve come a
long way since
the time of Hooke
(1665) thanks to
more
sophisticated
microscopes.
By the mid-1800s
there was an
established cell
theory.
Cell Theory
 Cells are the basic unit of organization of
living things
 Every living organism is made of one or
more cells
 All cells come from other cells already in
existence
Types of cells
 Two major categories:
 Prokaryotic
 Eukaryotic
Two subcategories:
Plant
Animal
Organisms made of eukaryotic
cells can be unicellular or
multicellular