SPECTROPHOTOMETRY, MICRO DISSECTION AND MICROMETRY

SPECTROPHOTOMETRY

DEFINITION
Spectrophotometry is the measure of amount of light that passes through the sample can be calculated that how much light was absorbed by the sample.
SPECTROPHOTOMETER
A spectropohtometer is a photometer that can measure intensity of wave length of light source.
OPTICAL DENSITY
Ability of specimen to absorb or block the passage of light.
FACTORS
The cell mass is directly proportional to the optical density. The amount of light passes through the solution is indicative of the concentration of certain chemicals that do not allow light to pass through.
APPLICATIONS
Spectrophotometry can be used to determined the wave length of light that take part 1 photosynthesis.

MICRO DISSECTION
It refers to a variety of techniques in which microscope is used for the dissection of cells or its organelles.
TYPES
Different kinds of techniques involve in micro dissection.
*) CHROMOSOME MICRO DISSECTION
To remove a portion from a complete chromosomes, a fine glass needle is being used under a microscope.
*) LASER MICRO DISSECTION
Use of a laser through a microscope for the dissection of selected cells.
*) LASER CAPTURE MICRO DISSECTION
Use of a laser through a microscope to cause selected cells to adhere to a film is called laser capture micro dissection.

MICROMETRY

DEFINITION
Measuring the size of microscopic objects is called micrometry.
This can be done by using specially designed scales.
(1) OCULAR MICROMETER
One of the scales is placed in eyepiece called ocular micrometer.
(2) STAGE MICROMETER
Other on the stage (stage micrometer) The micrometer have equally spaced divisions.
Before using the eyepiece micrometer to measure a particular structure, you will have to find out the real width of each unit on the scale at each magnification. In other words you have to calibrate the micrometer. This can be done by replacing the specimen with the stage micrometer, and to measure the eyepiece units at each magnification.