Tools of Biology:

light microscope

simple, compound

hand lens

stereo-microscope

phase contrast microscope

dissecting

Magnification

ratio of image size to object size

Resolution

closest distance two points can be that the microscope can see as two points.

For light the limit is

0.2 micrometers

(0.0000002 m)

due to the physics of light and lenses the smaller the the better the resolution

Metric review:

KHDODCM

Microscope parts-

optical system

lenses

light system

light, diaphragm

mechanical system

focus, stage

[Anton van Leewenhoek

first compound microscope

animalcules]

Since light must pass through the specimen, it must be thin and usually stained

Specimens are

fixed

stained

embedded in wax

and sectioned

Microtome-slices thin sections in embedded in wax

Phase contrast allows light to see some contrast in living specimens

Stereoscope

-two eyepieces

Dissecting scope

-two eyepieces & large stage

Micro dissecting tools:

tiny probes that can move parts of a cell around while on a microscope stage

electron microscope

Uses electrons rather than light

(much lower )

BUT-

A great deal of specimen prep necessary.

EMS operate in a vacuum-

SO-

specimens

dried

sectioned to 1 micron

stained with heavy metals

specimens can be magnified 250,000X

or more

Scanning EM

coat surface of object with gold, build image from reflected electrons

(Surface picture)

3D

Not as great resolution as EM, but 3D pictures

chromatography

separate materials based on mobility (density) in a solvent

chemical and physical properties

(usually on a gel or filter)

electrophoresis

separate materials based on mobility in a gel under electric field

(separates by size and charge)

centrifugation

separate materials based on density

ultra centrifuge (100,000 rev/sec)

can separate parts of cells

Spectrophotometry

light absorption by different chemicals is different at different wavelengths

Computers-

process data and present in understandable form

(raster of SEM; CAT scan)

Additional tools as noted in your text are also important