Name: ___________________________________
Period: ________
Due Date: ____________
The Cell Theory and the Scientists Behind the Theory: Read and Respond
Human understanding of nature
often follows the invention and
improvement of instruments that
extend human senses.
In 1590,
Zacharias Jansen, with the help of his
father, Han, was a Dutch spectacle
(eye glass lens) maker.
By putting several lenses in a tube, the pair discovered the
object near the end of the tube appeared to be greatly enlarged,
much larger than any simple magnifying class could achieve by
itself! Thus, the Jansen’s are credited with the invention of the first
microscope.
1. Who invented the first microscope?
Once people understood the physics behind the microscope,
improvements were made. Robert Hooke was an English scientist
who was interested in a lot of subjects, including nature. In 1665,
Hooke used a microscope similar to the one in the picture to observe
and study cork, which lies just under the bark of the cork oak tree.
The drawing that Hooke produced of the thin slice of cork looked a
lot like a honeycomb with a lot of little “compartments” that he
called cells. Hooke was actually observing the cell walls of dead
plant cells. Many more observations by many more scientists were
needed to understand the importance of Hooke’s discovery.
3. Who is credited with coming up with the
name “cell?”
Though he owned his own drapery business, Anton van
Leeuwenhoek was also an expert lens grinder. After seeing a copy of
Robert Hooke’s illustrated book, Micrographia, van Leeuwenhoek
began building his own microscopes. Unlike current microscopes
that used 2 lenses that magnified objects by 20 or 30 times, van
Leeuwenhoek was able to produce single lens microscopes capable
of magnifying objects up to 200 times!
5. Why is Anton van Leeuwenhoek referred
to as the “Father of Microbiology?”
Van Leeuwenhoek’s single lens
microscopes were very small (only 3-4
inches long), but so were the specimens
that he studied. Von Leeuwenhoek studied,
“animalcules”, unicellular organisms from
pond water.
Anton van Leeuwenhoek is often called the “Father of
Microbiology” because he is the first person to observe, draw, and
describe microorganisms with a microscope.
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2. How did the invention of the microscope
improve human understanding of the
world?
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4. What substance did Hooke study and
which organism produces it?
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6. How was Anton van Leeuwenhoek’s
microscope different from the
microscope that Robert Hooke used?
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After van Leeuwenhoek’s published
discoveries, people became more interested in
the world around them. In 1831, Scottish
botanist, Robert Brown is the first to discover
the dense structure inside of epidermal cells of
orchid plants and named the structure the
nucleus. Papers written by Brown suggested
that the nucleus was the center of cellular
creation.
7. Who discovered and named the nucleus
of the cell?
In 1838, after studying various plant
tissues from many different plants,
Matthias Schleiden, a German botanist,
concluded that all plant tissues are made up
of cells. He further proposed that an
embryonic plant arose from a single cell.
Schleiden further stated that the cell is the
basic building block of all plant matter. Both
of his observations were fundamental to
the cell theory.
8. What are the two contributions that
Schleiden made to the cell theory?
In 1839, German zoologist, Theodor
Schwann, concluded that all animal tissue
was composed of one or more cells. As a
professor
of
physiology,
Schwann
demonstrated that mature animal tissues
are traceable to embryonic cells.
10. What contribution did Theodor Schwann
make to the cell theory?
In 1855, taking Brown's original
description of nuclei and observations
by Karl Nägeli on cell division, the
German
physiologist,
physician,
pathologist, and anthropologist Rudolf
Virchow was able to add a third tenet to
the cell theory: “Omnis cellula e
cellula,” or all cells develop only from
existing cells. Working as a pathologist,
Virchow was the first person to
demonstrate that the cell theory
applied to diseased tissue as well as
healthy tissue, diseased cells arose from
healthy cells of normal tissue.
11. What was Rudolf Virchow’s contribution
to the cell theory?
The cell theory is one of the most important theories in the
field of biology and is comprised of three fundamental statements:
1.) All living things are made up of one or more cells 2.)Cells are the
basic units of structure and function, and 3.) New cells are produced
from existing cells.
13. What are the three statements of the
cell theory?
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9. What is the overall shape of a typical
plant cell?
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12. What important discovery about
diseased tissue was Virchow able to
demonstrate in his work?
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