httpswwwyoutubecomwatchv4OpBylwH9DU 6 min Lets review Cell Theory 3 Main Ideas All living things are composed of cells Cells are the basic units of structure and function in living things ID: 649135
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Slide1
Cell TheorySlide2
Wacky History of Cell Theory
https://www.youtube.com/watch?v=4OpBylwH9DU
(6 min)
Let’s review…Slide3
Cell Theory: 3 Main Ideas
All
living
things are composed of cells
Cells are the basic units of structure and function in living things
All cells are produced from other cellsSlide4
The Role of Microscopes
Many centuries ago Greek philosophers thought that organisms appeared from non-living or rotting material, and idea called
spontaneous generation
Example: A Recipe for Bees
(Roman, 2000 years old)
Kill a bull during the first thaw of winter
Build a shed
Place the dead bull on branches and herbs inside the shed
Wait for summer. The decaying body of the bull will produce beesSlide5
In 1665 Robert Hooke created and used a simple microscope to observe a piece of cork – noticed it was made up of air-filled sacs that he called
cells
. Slide6
In 1838, with more advanced microscopes, German biologists
Schleiden
and
Schwann
recognized that all plant and animal cells have a
nucleus and other key organelles. They proposed cells as the basic unit of life. Slide7
Finally Rudolf Virchow
(and Robert
Remak
) observed
cells and cell division, and determined that all cells come from other cells.
Our understanding of cell theory is dependent on
the microscope
! Slide8Slide9
Microscopes
Microscopes are devices that produce
magnified images
of structures that are too small to see with the “naked eye”
Two main types:Light microscopes which produce magnified images by focusing visible
light rays
Electron microscopes produce magnified images by focusing
beams of electronsSlide10
Light Microscopes
Most commonly used microscopes (the ones we have in the lab)
Can produce clear images of objects at
1000
times the magnification
Compound Light Microscopes allow light to pass
through
the specimen and use two lenses to form the image
Can observe cells and tiny organisms while they are
still aliveSlide11
Light Microscopes
Chemical
stains
and fluorescent
dyes
can be used to highlight structures and processes inside cells
Video cameras and computer processing can produce moving 3D imagesSlide12
Electron Microscopes
To study objects smaller than
0.2
micrometers (one fiftieth the diameter of a cell), an electron microscope must be used.
Can produce images 1000 times more detailed than a light microscopeSlide13
Two Main Types
Transmission
Electron Microscopes (TEM) send electrons
through
a specimen
Shows
detail inside the
cell
Scanning
Electron Microscopes (SEM) send electrons across the
surface
of a
specimen
Produces realistic three-dimensional images of objects
Both require a
vacuum
environment, so samples must be preserved and dehydrated
Therefore
cannot
be used to observe living cells.Slide14
Microscope Parts
Use the Information on
pg
1070 to fill out the diagram of the compound microscope