Before your Museum Visit: Microscopes
How do we know about the cells in our bodies?
How small is small?
Teacher information
As you know, we need microscopes to see both individual cells and microbes. A microbiologist might report that a poliovirus is 30 nanometers in diameter and that an E. coli cell is 3 micrometers long. Scientists use these measurement terms because microbes are so small, they cannot be measured using the more familiar inches or millimeters. (A micrometer is a thousand times smaller than a millimeter and a nanometer is one million times smaller than a millimeter.)
Try the Let's Get Small activity on Microbe World to investigate how small microbes are.
Uses of Microscopes
Discuss:
Why would a scientist need a microscope? Review the interview with Billie Juni. What things did she look at under a microscope?
Scientists use microscopes to see individual cells and the organelles in cells. Microscopes help scientists understand how all those parts in the cell work together and how cells come together to form tissues (like skin or muscles). Microscopes are also used to count cells when scientists are setting up experiments. Microbiologists like Billie Juni use microscopes to help identify bacteria.
Teacher information
Magnification
Not all microscopes magnify the same amount. If a microbiologist wanted to see a single skin cell they would use a compound light microscope. This kind of microscope can be used to see things ranging from 1millimeter to 1 micrometer. This size range includes all sorts of bacteria too, such as E. coli, which is 3 micrometers long.
If that same scientist wanted to see a virus like the influenza virus, which causes the flu, they would have to use microscope that could magnify over a thousand times more because the flu virus is only 80 nanometers. E. coli is almost 50 times bigger than the flu virus. This type of microscope is an electron microscope. Using an electron microscope scientists are able to see objects as small as a single atom - only 1 angstrom across. In fact electron microscopes can be used to see things in high resolution and give a three dimensional pictures for objects ranging from 10 micrometers to one angstrom in size. An angstrom is 10,000 times smaller than a micrometer. So, a single atom is more than thirty thousand times smaller than an E. coli bacterium. As you can see, there is some overlap in what microscopes can magnify.
For more information on microscopes try these websites:
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