Bio Tech-Talks by Dr. Abhimannue

  Spectrophotometry – Basic Instrumentation Objective: To understand the basic principle of spectrophotometry and the working of a UV-Vis spectrophotometer by measuring absorbance of a colored solution at a specific wavelength.   Principle: Spectrophotometry is based on the principle that molecules absorb light at specific wavelengths. The amount of light absorbed is proportional to the concentration of the solution (Beer-Lambert Law). Beer-Lambert Law : A = ε c l Where:   A = Absorbance ,  ε =  Molar absorptivity (L·mol⁻¹·cm⁻¹),  c  = Concentration (mol·L⁻¹),  l  =  Path length (cm)   Materials Required: ·           UV-Visible Spectrophotometer ·           Cuvettes (quartz or plastic, depending on wavelength) ·           Distilled water ·           C...

  Experiment No: Study of Cell Structure by Temporary Mounts of an Onion Peel   Objective: To prepare a stained temporary mount of an onion peel and to record observations and draw labeled diagrams. Apparatus and materials required: Onion, glass-slide, watch glass, cover slip, forceps, needles, brush, blade, filter paper, safranin, glycerine, dropper, water, and a compound microscope.   Theory: All living organisms are made up of cells. The shape, size and the number of these units vary in organisms. The three major components of a cell are the cell membrane, cytoplasm and nucleus. In a plant cell, a cell wall surrounds the cell membrane.   Procedure: 1.   Take an onion and remove its outer most peel. 2.   Now cut a small part from an inner scale leaf with the help of a blade. 3.    Separate a thin, transparent peel from the convex surface of the scale leaf with the help of forceps. 4.   Keep this peel in a watch g...