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Biology LibreTexts

5.3: Lipids

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  • Lipids

    Lipids include oils, fats, and waxes. Lipids provide stored energy, are essential components of cell membranes and are the building blocks of certain hormones. Dietary lipids are insoluble in water and cannot be utilized by the body unless broken down into smaller molecules. The body digests lipids by breaking them down into tiny components by emulsification with bile salts and by enzymes called lipases. The emulsification of lipids occurs in the small intestine.



    Emulsification of lipids


    • test tubes and rack
    • vegetable oil
    • water


    1. Draw a line at the 1 cm mark and the 2 cm mark on 2 test tubes.
    2. Add vegetable oil to the 1 cm mark in both test tubes.
    3. Add an additional cm of water to each test tube.
    4. Add 10 drops of detergent to one of the tubes
    5. Cover the tubes with parafilm and shake vigorously about 30 times (instructor will demonstrate).


    1. Describe the results (do not include the presence of foam) with respect to lipid

    2. Identify the experimental variable in the lipid experiment.

    3. Which tube represents the control group in the lipid experiment?

    4. List 3 controlled variables in this experiment

    5. What is the dependent variable in the experiment?