Transcript Cell Theory - pams

Cell Theory and Microscopes
41. Explain with evidence how the theories about life
changed over time.
42. State the cell theory and explain how the invention
of the microscope helped the development of the
theory
S.C.H.1.4.1
S.C.H.1.4.2
S.C.H.1.4.3
S.C.H.3.4.2
B. Thomas
Intro to the light Microscope
Homework
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• INTRODUCTION TO THE LIGHT
MICROSCOPE --Internet Lab—
Familiarize yourself with the microscope,
run the tutorial and examine the parts you
will be working with.
Complete handout activities
http://www.udel.edu/biology/ketcham/micr
oscope/
Due Date: ____________
History of Cell Theory - Janssen
• Credit for the first
compound (more than
one lens) microscope is
usually given to
Zacharias Jansen, of
Middleburg, Holland,
around the year 1595.
• Janssen and his father
made a compound
microscope by placing
two convex lenses at
each end of a tube
History of Cell Theory - Hooke
• In 1663 an English
scientist, Robert Hooke,
discovered cells in a
piece of cork, which he
examined under his
primitive microscope
• Hooke observed small
empty like structures
which he named cells
• The cells that Hooke
observed were nonliving
History of Cell Theory - van
Leeuwenhoek
• Anton van Leeuwenhoek
was the first to observe
and describe magnified
living things with simple
microscope. (working
between 1670s-1680s)
Leeuwenhoek was the
first to see bacteria from
teeth scrapings and
animal-like protist from
pond water
History of Cell Theory - Brown
• Around 1833 Robert
Brown reported the
discovery of the
nucleus.
• In the course of his
microscopic studies of
the epidermis of
orchids, discovered in
these cells "an
opaque spot," which
he named the nucleus
History of Cell Theory - Schleiden
• It was the German professor of
botany at the University of Jena,
Dr. M. J. Schleiden, who
brought the nucleus to popular
attention, and to asserted its allimportance in the function of a
cell.(1838)
• He came to believe that the
nucleus is really the most
important portion of the cell, in
that it is the original structure
from which the remainder of the
cell is developed
History of Cell Theory - Schwann
•
The following year, Dr Theodor
Schwann (1839) who worked with
animals, stated that all animals are
made of cells.
•
Schwann published a book on
animal and plant cells. He
summarized his observations into
three conclusions about cells:
1) The cell is the unit of structure,
physiology, and organization in living
things.
2) The cell retains a dual existence as a
distinct entity and a building block in
the construction of organisms.
3) Cells form by free-cell formation,
similar to the formation of crystals
(spontaneous generation).
Question: Which of these three
conclusions do we know not to be
History of Cell Theory - Virchow
• We know today that the first two
tenets are correct, but the third is
clearly wrong.
• The correct interpretation of cell
formation by division was finally
promoted by others and formally
enunciated in Rudolph Virchow's
powerful 1859 proclamation,
"Omnis cellula e cellula"... "All cells
only arise from pre-existing cells“
• Rudolph Virchow proposed that
cells can only arise from previously
existing cells.
The Cell Theory
The modern tenets of the Cell Theory include:
1. All known living things are made up of cells.
2. The cell is structural & functional unit of all living things.
3. All cells come from pre-existing cells by division.
(Spontaneous Generation does not occur).
– Cells contains hereditary information which is passed from
cell to cell during cell division. (The first cell is the
exception because it could not have come from a
previously existing cell)
– All cells are basically the same in chemical composition.
– All energy flow (metabolism & biochemistry) of life occurs
within cells.
The Cell Theory is to Biology as Atomic Theory is to
Physics.
Journal Entry
• What are the implications of the cell
theory?
• Due: __________
Microscopes
• That gizmo pictured to the left
is a BIG deal. It literally
opened up worlds of
organisms and information to
scientists. It's importance in
the history of medicine and
our understanding of disease
should not be
underestimated.
• That gizmo is a compound
light microscope.
• For you, the biology student,
it is perhaps the most
important tool for you to
understand. . .
• In learning about the cell the
microscope is the most
Light Microscope lab
• In Pairs of two, examine your compound
light microscope.
• Label all the parts of your compound light
microscope on the sheet provided to you.
• You will be quizzed on the structure,
function and uses of the compound
microscope.
E- Microscope Lab
• Lab on the use of the
microscope
• Lab pairs of two.
• Complete Lab Activity
Sheet.