WHAT ARE SOME THE IMPORTANT DISCOVERIES MADE BY
SCIENTISTS?
The cell theory resulted from the invention of the microscope
1. Robert Hooke: Improved the first microscope and observed cork cells
and named then “Cells” because they looked like the cells of a
monastery. He observed dead plant cells (cell wall)
2. Anton Van Leeuwenhoek: Made a simple microscope (270x) one lens
and observed pond water and saw microscopic organisms: paramecium,
euglena, amoeba etc…
3. Matthias Schleiden: Theorized plants are made of cells
4. Theodor Schwann: Theorized animals are made of cells
5. Rudolf Virchow: All cells come from preexisting cells.
Where did I come from?
What is the CELL THEORY?
1) All living things (organisms) are made up of one or more cells
2) All cells carry on their own life functions: Unit of function and structure
for all living things.
3) New cells arise from other living cells by cell division
What are the exceptions to the cell theory?
1. Where does the first cell come from? This is questionable.
2. Viruses: Not made up of cells, However:
They have DNA and need a host to reproduce
3. Mitochondria and Chloroplasts: behave like cells but are not cells.
They have their own genetic material.
Types of Microscope:
simple microscope has one lens similar to a magnifying glass
Compound microscope multiple lenses (eyepiece & objective lenses)
1. Stereomicroscope: 3D image
2. Electron microscope: Most powerful microscope magnifies up to
1,000.000x there are 2 types SEM (scanning electron microscope)
produces a realistic 3D image only on surface of the specimen and
TEM (transmission electron microscope) produces a 2D image of a
thinly sliced specimen.