Download The Microscope

The Microscope
And the cell theory
Robert Hooke (1665)
• First discovered cells
• He looked at a slice of cork under a
“primitive” microscope
• The cells looked like honeycomb
shaped structures
• Hooke used the word “cell” to
describe those shapes
Anton van Leeuwenhoek
• Observed living blood cells, and
bacteria a few years later
• Leeuwenhoek is called the “father of
microscopy”
• A few years later, Robert Brown ,
looked at plant cells and described a
dark sphere at their center, the
nucleus
Cell Theory
• 1) All living things are composed of
cells.
• 2) Cells are the smallest unit of life.
• 3) All cells come from pre-existing
cells.
• Brain Pop
– Microscopes
– Cell Structure
Compound Microscopes
• An important development to
microscopes was adding the second lens
• The eye piece (occular lens) magnifies
the image 10x
• By adding a second lens that also
magnifies by 10x the total magnification
becomes 100x (10 x 10)
• By how much is an object magnified when
viewing it under high power (40 x)?
Transmission Electron
Microscopes
• Today TEMs can magnify objects by
2 000 000 times
• Instead of light, TEMs use beams of
electrons to magnify images
• TEM’s have two limitations
– 1. They can’t magnify specimens that
contain many layers of cells
– 2. They can only magnify dead cells
Scanning Electron
Microscopes
Microscopes
• Can magnify thick specimens
• Provide a 3-D image
• Limitations
– Cannot magnify as much as TEMs
– Resolution (focus) is not as good as
TEMs
Proper Use of a Microscope
1. Always carry with one hand on the
arm and one hand on the base
2. Always begin on low power
3. Never use coarse adjustment on
high power
Bacteria
• Bacteria, Germs and viruses are some
things that we can use microscopes to
investigate
• Bacteria are one celled microorganism
• They can be beneficial- yogurt
• They can be harmful- tetanus and
pneumonia
Bacteria
Cell City- Project
• From your knowledge of cell organelles
and the descriptions on the worksheet,
match up the cells that do the correct
function.
• Today you just have to correctly match up
the worksheet
• Tomorrow we will be creating “Cell City
Maps” on Art Paper
• This will help you remember the different
parts of each organelle
• Two people to a group
• Bring Markers and Pencil Crayons !