Transcript 1- Cell Theory - WordPress.com

The Development of the
Cell Theory
Cell Biology
Prepared by: A. Abougabal
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
1600
1500
Ancient Times
• Ancient peoples are
always on the look-out
for
ways
that
organisms
can
be
used by them.
• Some
civilizations
support “great thinkers”
and philosophers, but
they rarely base their
thoughts on observation
or experiments.
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
1600
1500
334 B.C.E - Aristotle
• Greek
philosopher,
Aristotle,
begins
to
observe nature.
• He classifies all known
organisms as either a
Plant or and Animal.
• He writes that living
things
can
arise
spontaneously
from
non-living matter.
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
1600
1500
1268 – 1st Eyeglasses
• Roger Bacon, an
English friar makes
reference to a pair of
eye glasses.
• This means that glass
is being developed
and used in a way that
makes it easier to see
small things.
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
1600
1500
1590 – 1st Microscope
• Zacharias Janssen, a
Dutch eyeglass maker,
makes the 1st microscope
by placing two lenses on
top of one another to make
extra-large images.
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
1000
300 BCE
1600
1500
1800
1700
1900
1600’s
• People start to question the
origins of life.
• Many begin to suggest that life
can only come from other
forms of life rather than
through
spontaneous
generation (as was suggested
by Aristotle). This only took
about 2000 years!
• William Harvey says that
maggots do not come from
the meat itself but from tiny
eggs too small to be scene.
William Harvey
English Physician
1578-1657
Cell Theory and
the Scientists
Who Helped
Shape It
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
1600
1500
1800
1700
1674 – 1st Microscopic Beasties Seen!
• Anton van Leeuwenhoek (1632-1723)
reports being able to see tiny beasties (0.002
mm) using a simple single-lens microscope.
He is known as
the
“Father of
microscopy.”
1900
Anton van Leeuwenhoek
he documented unicellular organisms based on
observations of protozoa [1673] and bacteria [1683]
Robert Hooke
• Born: July 18, 1635
• Died: March 3, 1703
• Wrote and published
“Micrographia”
• Known as the
“English
http://www-groups.dcs.st-and.ac.uk/~history/PictDisplay/Hooke.html
Father of
microscopy”
Robert Hooke
Contributions:
– [1665]
He
observed
pieces of cork from the
bark of a cork tree under
the microscope.
– His observations led him
to coin the word “cell.” “Cell”
means
little
rooms in Latin
http://www.learner.org/channel/courses/essential/life/s
ession1/closer1.html
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
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1600
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1800
1700
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1667 – Species Defined
• John Ray (1627-1705)
defines a “species” as a set
of individuals that can
reproduce their own kind.
• The beginning of the end of
spontaneous generation!
William Harvey
English Physician
1578-1657
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
1000
300 BCE
1600
1500
1800
1700
1668 – 1st Experiments about origins of maggots
• Francesco Redi (1626-1697)
conducts experiments to prove
that maggots do not appear
in meat if flies cannot land
on it!
William Harvey
English Physician
1578-1657
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
1000
300 BCE
1600
1500
1700’s
• Microscope claimed to
be an instrument of evil
when a prominent person
was horrified by the sight
of a magnified flea!
• Scientists
begin
to
doubt
spontaneous
generation,
but
the
common people still
believe in it!
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
1600
1500
1800
1700
1770 – Advancement of microscopes
• Microscopes
become
sturdier and easier to use.
• Flaws in glass production
still causes images to be
blurry and have coloured
halos.
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
1000
300 BCE
1600
1500
1800
1700
1809 – 1st Science Texts for Students
• Jane
Haldimand
(1769-1858)
writes
textbooks for young
people to learn about
science.
• Terms
such
as
“cellular
system”
and
“Cellular tissue”
“cell”,
appear in the book.
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
1000
300 BCE
1600
1500
1800
1700
1825 – Book “Cells from Cells”
• Francois
Vincent
Raspail (1794-1878)
wrote a book called
(translated from Latin)
“Every cell is
derived from a
pre-existing
cell”.This
again
puts to rest the idea
of
spontaneous
generation.
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
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1830 – Cells are studied
• Biology is becoming an
important science and
the body of knowledge
is growing, especially
since the improvement
of microscopes.
• Scientists
begin
to
study
the
cell
extensively!
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
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1831 – Nucleus of Cell Found
• Robert Brown (1773-1858)
is the 1st to consider the
nucleus as a regular part
of a living cell.
• The nucleus is still hard to
see though without the
invention of the electric
light for his microscope.
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
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1838 – Plant cells!
• Matthias
Jacob
Schleiden (1804-1881)
makes the claim “All
plants are made of cells”.
• Cells are alive!
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
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1839 – Animal cells!
• Theodor
Schwann
(1810-1882) makes the
claim “All animals are
made of cells”.
• “All living things are
made of cells”
• Cells are the basic
building blocks of life!
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
1000
300 BCE
1600
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1845 – Cell Basic Unit of Life
• Alexander
Carl
Heinrich Braun (18051877) makes the claim:
“The cell is the basic
unit of life”.
• Cells are made of
protoplasm enveloped
by
a
flexible
membrane.
1800
1700
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
1000
300 BCE
1600
1500
1800
1700
1860’s, The end of the “Spontaneous
Generation” debate
• Louis Pasteur (18221895)
• conducts a series of
experiments that once
and for all put to rest
the
idea
of
spontaneous
generation
and
concluding that living
organisms do not
arise from nonliving matter.
1900
Who came up
with the theory?
• Major Contributors:
• Matthias Schleiden
• Theodor Schwann
• Rudolph Virchow
1-Rudolph Virchow
• German pathologist
• He is known as the
Father of
Pathology.”
“
Born: October 13, 1821
Died: September 5, 1902
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory
500 BCE
300 BCE
1000
1600
1500
1800
1700
1900
Rudolph wirchow stated “omnis cellula a cellula ”
[all cells arise from pre-existing cells based on
observations of dividing cells [1855]
All cells
come from
pre-existing
cells!
• Cell Theory
Virchow
• that is still largely
accepted today.
proposed that cells were the fundamental units of plants
based on observations of plant tissue [1838]
2. Schleiden (1838)
All plants are
made of cells!
German botanist
Born: April 5, 1804
Died: June 23, 1881
Onion skin cells
Plant cells
Who came up with this theory?
proposed that cells were the fundamental units of animals
based on observations of animal tissue [1839]
3. Schwann
All animals are
made of cells!
• German zoologist
Born: December 7, 1810
Died: January 11, 1882
/
Human red blood cells
Blood
Sperm
Schleiden and Schwann
The Cell Theory [1839]
• All living things are made of cells.
• Cells exhibit the fundamental characteristics of life:
–
–
–
–
–
–
–
–
–
–
Obtain energy—photosynthesis, chemosynthesis, or digestion
Use energy—respire
Excrete Waste
Show Order
Homeostasis
Evolve
Reproduce
Move
Respond to changes in environment
Grow and repair damage to self
The Cell Theory States:
• As written by Rudolph Virchow (18211902):
– All living organisms are made of one or
more cells.
– Cells are the basic units of structure
and function in all organisms.
– All cells come from previously existing
cells.
– The activity of an entire organism
depends on the total activity of its
independent cells.
Definition
= Three part theory about cells
1. All living things are made of cells.
Part 2 of the Theory
2. The cell is the basic structural
and functional unit of life.
Part 3 of the Theory
3. All cells come from pre-existing
cells.
yeast cells dividing
How big are cells?
• Microscopic
(mostly)
• Measured in
microns µm
• (micrometers).
• A µm is one
millionth of a
meter =
• 10-9 m = one
thousandth of 1
mm.
How big are cells?
Smallest free-living cell =
Mycoplasma genitalium
Size = 0.2 to 0.3 µm
How big are cells?
• Bacteria e.g. Eschericia coli (aka
E.coli)
• Size=1 µm by 3 µm
How big are cells?
• Human red blood cell =
• 8 µm in diameter
How big are cells?
• Largest cell on
the human body
= ovum
• Size=
• 1000 µm in
diameter
(1 mm)
How big are cells?
• Smallest cell in the human body =
sperm cell.
How can we study cells?
Problem:
They are microscopic!
Solution:
Use a microscope!
Cell biology
• Cell biology is the study of cell structure and
function, and it revolves around the concept
that the cell is the fundamental unit of life.
• Focusing on the cell permits a detailed
understanding of the tissues and organisms that
cells compose.
• Some organisms have only one cell, while others
are organized into cooperative groups with huge
numbers of cells.
• On the whole, cell biology focuses on the
structure and function of a cell, from the most
general properties shared by all cells, to the
unique, highly intricate functions particular to
specialized cells.
Microscopes
A. COMPOUND
MICROSCOPE
1. Compound light
microscope
– Light passes
through lenses to
magnify image up
to 1000X
– Can observe
living cells
Light Microscope
Human Cheek Cell
Nerve Cells
B. STEREOMICROSCOPE
• Gives 3D images
of specimen
C. SCANNING ELECTRON
MICROSCOPE (SEM)
1. Uses electrons instead of
light to project surface
image of specimen
SCANNING ELECTRON
MICROSCOPE (SEM)
2. Electron
microscope
– Uses a beam of
electrons to
magnify image
> 1000X
– Kills cells being
observed
Scanning Electron
Microscope
Human Sperm
Insect Head
D. TRANSMISSION ELECTRON
MICROSCOPE (TEM)
1. Works like light
microscope except
uses electrons
Transmission Electron
Microscope
Plant Cell
Mitochondrion
Comaparison of Light and Electron
Microscopes
Microscopic measurements
mm – millimeters
μm – micrometer
nm - nanometers
1m = 1000mm = 1000,000μm=
1000,000,000nm
Assignment #1
which microscope can be
used to study the following
Sizes of Biological Structures
•
•
•
•
•
•
•
•
•
•
Thickness of leaf
Paramecium
Sharp end of pin
Plant cell
Animal cell
Mitochondrion
Bacterium
Ribosome
DNA molecule
Hydrogen atom
•
•
•
•
•
•
•
•
•
•
O.5mm
200μm
100 μm
40μm
20μm
1μm
0.5-1μm
20nm
2nm
0.04nm
Thanks
And That is the end
And, what about viruses?
• Are not composed of cells but
consist of a nucleic acid (DNA
or RNA) in a protein coat
• Yet conduct all of the cell
processes (although with help,
not independently)