Biology Chapter 7.1 Notes-Microscope
Chapter 7.1 Voc word List (include people):
People: Robert Hooke, Anton van Leeuwenhoek, Mathias Schleiden, Theodor Schwann
Voc. Words: Compound Light Microscope, Scanning Electron Microscope, Transmission Electron
Microscope, Scanning Tunneling Microscope, Cell theory, Prokaryotes, and Eukaryotes
Section 7.1: The Discovery of Cells
Cell Theory History/Microscopes
 Before microscopes people believed that diseases came from curses and supernatural
spirits.
 When microscopes were invented scientists found cells and microorganisms
Simple Light Microscope-one lens microscope
 Robert Hooke developed a gold-embossed leather case in 1665 for a simple
compound microscope
o English scientist
o He looked at cork cells (dead oak tree bark) and observed and drew the
structures he saw
o He called the structures- cells
 Anton van Leeuwenhoek designed and used simple light microscope in the late
1600’s –early 1700’s
o Dutch scientist
o By 1700 he developed 240 single-lens versions
o He was the first to discover and describe red blood cells and bacteria and is
often credited as the invention of a microscope-invented many years before
his birth
 Mathias Schleiden was a German scientist that studied a variety of plants under the
microscope in the 1830’s and determined that all plants are made of cells
 Theodor Schwann was another German scientist that studied a variety of animal
cells and determined all animals are made of cells
Microscopes were developed over the next 200 years with series of lenses to magnify objects
1 Compound Light Microscope- Uses light and more than one lens to look at
living cells (Can magnify up to 1500 times)
2 Scanning Electron Microscope- (SEM) sweeps a beam of electrons over the
surface of the specimen causing electrons to be emitted from the specimen
(3-D realistic pictures with magnification up to 20,000 times)
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3 Transmission Electron Microscope-(TEM) aims a beam of electrons through a
specimen
 Invented and developed in the 1930’s-1940’s
 Makes 2-D images
 Denser portions are darker
 Used to study details of cells
 Magnification up to hundreds of thousands times
4 Scanning Tunneling Microscope-(STM) invented in the 1980’s and
revolutionized microscopy because scientists were able to see atoms on the
surface of an object
 A very fine metal probe is place near the object.
 Electrons flow between the tip of the probe and the atoms on the
surface of the specimen
 Can see objects such as DNA molecules
 A computer makes the 3-D image
 Magnification can reach 100 million times
Cell Theory
1 All organisms are composed of one or more cells
2 The cell is the basic unit of structure and organization of organisms
3 All cells come from preexisting cells
Two basic types of cells
o All cells contain specialized parts known as organelles
 Many organelles are protected with membranes
 Each organelle as a specific function in the cell
1 Prokaryotes
a. These cells do not contain membrane bound organelles
b. Their nucleus is incomplete
c. Parts include: cell wall, one strand of DNA, plasma membrane, cytoplasm,
ribosomes
d. These cells are 0.001 mm to 0.1 mm in size
e. Usually unicellular bacteria
2 Eukaryotes
a. These cells do contain membrane bound organelles
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b. Most organisms with this type of cell are multicellular but a few like the amoeba
and some algae are unicellular
c. Parts include: Plasma membrane, cytoplasm, complete nucleus with
chromosomes, nucleolus, and organelles
d. These cells are 0.01 mm to 0.1 mm in size
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