Tools of a Biologist

Microscopes: number one tool of a biologist

• Micro= Scope=– Small -to view

A microscope is an instrument used to view very small objects.

In biology we will use it to view…. living cells and unicellular organisms.

Compound Light Microscope

There are 3 types of microscopes used in biology:

1. Compound light microscope-Compound-

look through 2 lenses at the same time in order to properly magnify the organism.

Total magnification:

low power:ocular lens x10low objective x4

-------------- x40

medium power:ocular lens x10low objective x10

-------------- x100

high power:ocular lens x10low objective x40

-------------- x400

Compound light microscope:

-light -light must pass through the diaphragm and through the

object.

-object must be “thin” or transparent so the light can

pass through it.-Diaphragm:

regulates the amount of light that can pass through.-Best setting of the diaphragm is #2

StainingThe purpose is to:

add color to a cell so that the cell and its structures can be seen more clearly through a microscope.

Limit of Resolution-is the point at which you see an item most clearly.

Any magnification above or below that point will results in the object looking blurry.

Type 2: Stereoscope-Used to view the surface of objects which are too large for light to pass through them.

-Uses 2 lights to illuminate the surface of the object.

-Stereo means “3 dimensional”

-Provides a 3-D detailed look at the surface of an object.

-look through2 ocular lenses

-magnifies between x10 to x60

Type 3: Electron Microscopes Uses electrons to form an image and NOT lightHas a very high limit of resolution.

-can see items very clearly at any magnification-can magnify up to 500,000x and still be clear

Object is placed in a vacuumNo airNo oxygenOrganism is DEAD

• Produces a 2-D, black and white image of inside of a cell.

Two types of electron microscopes:

1. T.E.M. ~ Transmission Electron Microscope

2. S.E.M. ~ Scanning Electron MicroscopeProduces a 3-D, black and white image of the surface of an object.

Additional tools of a biologist:

• Chromatography:Tool used to separate the components of a mixture by their different densities.

Link to graphing