Tools of a Biologist

Microscopes• Micro= Scope=– Small -to view

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

In biology it is used to view living….cells and unicellular organisms.

Compound Light MicroscopeEyepiece / Ocular lens

X10Nose

Arm

Course Adjustment knob:

Moves stage up and down

Stage and Stage clips

Fine adjustment knob:

Fine focuses the image for your eyes

Revolving lenses

Low power objective lens.

Shortest lensRed in colorX4

Medium power objective lens

Medium in lengthYellow in colorX 10

High power objective

Longest in lengthBlue in colorx40

Light source

Base

Diaphragm: regulates the amount of light that passes through the stage

There are 3 types of microscopes are 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 x10

med objective x10-------------- x100

high power:ocular lens x10

high 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.

StainingIs a method of adding color to a cell so that the cell and its structures can be seen more clearly through a microscope.

Limit of ResolutionThe 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 to 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.