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Learning Goal 9.4 – 8.15
• Students will describe how continuous
investigations and new scientific
information influenced the
development of the cell theory.
http://www.sikharchives.com/wp-content/uploads/2010/02/nerve_cell.jpeg
http://www.environmentalgraffiti.com/featured/images-inside-human-body-images/8292?image=13
http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm
Topic 3: Cells
3.1 Cell Theory
ENDURING UNDERSTANDING:
The cell’s structure and function act together providing the
homeostatic unit of life.
ESSENTIAL QUESTIONS:
What are cells and how were they discovered?
ESSENTIAL QUESTIONS:
What does the cell theory tell us about cells?
History
• 1665 – Robert Hooke
builds a compound
microscope and
observes thin slices of
cork
• Coins term “cells” to
describe the boxlike
structures
• What he actually saw
was cell wall remains
of dead plant cells.
Learning goal: Students will describe how continuous investigations and
new scientific information influenced the development of the cell theory.
History
• 1673 – Anton von
Leeuwenhoek reports
observations of
microorganisms in pond
water
• He built a sophisticated
simple microscope
http://www.ucmp.berkeley.edu/history/leeuwenhoek.html
History
• He calls them “animalcules”
• He observed protists,
bacteria, spermatozoa & red
blood cells
History
Schleiden
http://vlp.mpiwg-berlin.mpg.de/people/data?id=per134
• 1839 – Matthias
Schleiden and
Theodor Schwann
propose the first two
parts of the cell
theory:
Schwann
http://vlp.mpiwg-berlin.mpg.de/people/data?id=per136
– All organisms are
made up of one or
more cells
– Cells are the
fundamental and
structural unit of life
Learning goal: Students will describe and/or explain the cell theory.
History
• 1858 – Rudolph
Virchow proposed
that all cells come
from pre-existing cells
This image is a work of the National Institutes of Health, part of the United States Department of Health and Human
Services. As a work of the U.S. federal government, the image is in the public domain.
Cell Theory:
• All organisms are
made up of one or
more cells.
• Cells are the
fundamental and
structural unit of
life.
• All cells come from
pre-existing cells.
Evidence for the cell theory
• Following invention of the microscope:
– Schleiden recognized that all plant cells were
composed of cells
– Schwann recognized that all animal tissues
were also composed of cells
– Since that time, more organisms have been
examined, all consisting of cells
Evidence for the cell theory
• Prior to the addition of “all cells come
from pre-existing cells”, or abiogenesis:
– Redi performed an experiment that
disproved spontaneous generation of flies on
rotting meat; supporting the idea that life
comes from pre-existing life (and life is made
of cells).
Evidence for the cell theory
• Prior to the addition of “all cells come
from pre-existing cells”, or abiogenesis:
– Spallazani disproved Needham’s hypothesis
of spontaneous generation of microbes in
soup – discovering that soup that was kept
sealed did not have microbes present and
that they must come from the air.
Evidence for the cell theory
• Prior to the addition of “all cells come
from pre-existing cells”, or abiogenesis:
– Later, Pasteur repeats Spallazani’s
experiment, proving that microbes were in
the air with a unique S-shaped flask which
caught the microbes.
Evidence for the cell theory
• Since the discovery of cells:
– Nucleus was discovered (Brown)
– Inheritance was figured out (Mendel,
Weismann))
– Chromosomes were discovered (Walter
Fleming)
Works Cited
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http://www.ucmp.berkeley.edu/history/leeuwenhoek.html
www.microimaging.ca
http://candaceb.myweb.uga.edu/Binary%20Fission.html
http://vlp.mpiwg-berlin.mpg.de/people/data?id=per134
http://vlp.mpiwg-berlin.mpg.de/people/data?id=per136
http://www.timeline-help.com/the-cell-theory-timeline.html
http://kentsimmons.uwinnipeg.ca/cm1504/15lab42006/lb4pg7.htm
http://www.fungalcell.org/hyphal-tip-growth-and-branching-image-gallery
http://www.funsci.com/fun3_en/protists/exhibition.htm
http://www.cs.tufts.edu/~frisken/chainMail-Enhanced.pdf
http://www.kidsmathgamesonline.com/pictures/numbers/number1.html
http://www.kidsmathgamesonline.com/pictures/numbers/number2.html
http://www.iconspedia.com/icon/arrow-16128.html