Lipids

Background: Lipids are a heterogeneous group of compounds synthesized by organisms that are

present in all biological tissues. These compounds are characterized as being sparingly soluble in

water, but highly soluble in nonpolar solvents (e.g., chloroform, ether, hexane, etc.). We can use

this solubility difference to extract and separate lipid constituents from the many polar

compounds that are contained in biological tissues. Lipids can be classified by a number of

schemes, but looking at them according to their biological function is most useful. Triglycerides

(or triacylglycerols) are fats and oils that serve as storage and transport forms of metabolic

energy. These compounds contain fatty acids (generally 3 molecules of saturated and unsaturated

in various combinations) that are esterified to a 3-carbon glycerol molecule. Waxes (long chain

fatty acids esterified to a long chain alcohol), hydrocarbons (long chain alkanes) and fatty

alcohols form protective surfaces on many plant and animal tissues. Lipids that are membrane

components are usually amphipathic and complex (phospholipids, sphingolipids, glycolipids).

Finally, there are a large group of low molecular weight, non-polar compounds that are not

derived from fatty acids (e.g., steroids, vitamins, carotenoids, quinones, etc.) and function as

hormones, vitamins, photopigments and other specialized roles. In the first part of the

experiment, you will obtain a crude lipid fraction from either plant and/or animal tissues. You

will analyze the lipids contained in your extracts using two dimensional (2-D) thin layer

chromatography (TLC) and measure the cholesterol content by spectrophotometry.

Metodes:

In eksperiment een word die Na2S2O3-oplossing gestandardiseer om die konsentrasie daarvan te bepaal. Voeg eerstens 10 mL 10% KI-oplossing in twee afsonderlike 250 mL Erlenmeyerflesse. Voeg 40 mL gedistilleerde water en 10 mL 50% H2SO4 by elke fles. Pipetteer presies 10.00 mL KMnO4-oplossing...