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Chapter 7: Cell Structure & Function
I. Life is Cellular
A. The Discovery of the Cell
Famous Scientists & the Cell Theory :
1. Robert Hooke – (1665) English
scientist who used an early
compound microscope to
look at thin slices of cork.
-1st used the word “cell”,
referring to tiny, empty
chambers that make up plant cork.
2. Anton van Leeuwenhoek – Dutch
scientist who used a single-lens
microscope to view pond water &
other things. Was a lens-maker.
Famous Scientists & the Cell Theory
3. Matthias Schleiden – (1838)
German botanist who 1st
concluded that all plants are
made of cells.
4. Theodor Schwann – (1839)
German biologist who 1st
concluded that all animals
are made up of cells.
-Said all living things are made
of cells.
5. Rudolf Virchow – (1855)
German physician who
concluded that new cells only
come from existing cells.
Famous Scientists & the Cell Theory
*Work done by these scientists
led to the development of the
cell theory.
The cell theory states :
1. All living things are made of
cells.
2. Cells are the basic unit of
structure function in living
things.
3. New cells are produced from
existing cells.
B. Exploring the Cell
*New techniques & microscopes
are now used to explore the cell
closely.
Techniques :
1. Fluorescent labeling – follows
molecules moving through a cell.
2. Confocal light microscopy –
scans cells w/ laser beam; used
to build 3-D images of cells & cell
parts.
3. High-resolution video technology
- produces movies of cells as
they grow, divide, & develop.
Types of Electron Microscopes
1. TEMs – (transmission electron
microscopes) used to study cell
structures & protein molecules.
2. SEMs – (scanning electron
microscopes) scan
surfaces of specimens & make
3-D images.
3. Scanning probe microscopes –
trace surfaces of samples with
a fine probe. Great for
surfaces; can view single
atoms.
C. Prokaryotes and Eukaryotes
All cells have 2 characteristics :
1. Have a cell membrane.
2. Contain DNA.
2 Major Divisions of Cells :
Eukaryotic – cells that contain a
nucleus and many organelles, ex :
plant & animal cells.
-Larger/complex cells that are
highly specialized (parts = specific
functions).
-Nucleus stores genetic material
separately from the rest of the cell.
-Have great variety; can be single
or multicellular.
Prokaryotic – cells with no nucleus
& few organelles, ex : bacterial cells.
-Usually smaller/simple & have
genetic material that isn’t
contained in a nucleus.