Practicals

• A mole is the gram molecular weight of an element / compound and comprised of 6.023 x 10^23 atoms or molecules (Avogadro's number)
• Molarity is the unit used to describe the number of moles of a chemical or compounds in one litre of solution
• To make a 2M sodium chloride solution: Multiply the FW of sodium chloride (58.44) by 2 moles per litre
• The Biuret Assay, Bradford Assay or Lowry method can be used to test for proteins
• Biuret Assay: Blue to purple - Positive, No colour change - Negative
• Spooling of Salmon Sperm DNA: Pipette 0.5 ml of DNA solution into test tube, slowly pipette 0.5 ml 3M sodium acetate solution, mix by swirling, slowly pipette 2 ml of absolute ethanol, mix by inverting, observe precipitation, spool with glass rod
• Gel electrophoresis of dyes: Pipette 10 μl of each dye sample into each well of the agarose gel, a voltage of 100 volts is applied to the gel for 20 minutes, the dyes are pulled by the positive charge at varying speeds based on size
• Testing for oils: Pipette 1 ml of oil & 1 ml of ethanol into tube 1 & shake, pipette 2 ml of distilled water into tube 2, carefully pour tube 1 into tube 2, oil appeared suspended in water as a cloudy white emulsion (milk control dissolved)
• Testing for presence of lipids: draw 4 squares onto brown paper and swab 3 lipids into separate squares and water onto a fourth as a control, wipe off excess and leave dry, lipids leave a translucent spot behind
• Benedict's test for monosaccharides: Pipette 2 ml of glucose solution into test tube 1, pipette 2 ml of sucrose solution into test tube 2, pipette 2 ml of starch into test tube 3, pipette 1 ml of benedict's solution into each, incubate tubes in a 50 degree water bath for 10 minutes, colour change from blue to brick red for tube 1 shows positive, no colour change for tubes 2 & 3 shows negative
• Iodine test for starch: Pipette 2 ml of glucose solution into test tube 1, pipette 2 ml of sucrose solution into test tube 2, pipette 2 ml of starch into test tube 3, pipette 2 ml of pasta into test tube 4, add 3-4 drops iodine to each, brick red to bluish black colour change for starch and pasta is positive