26.3. Lipids http://www.ck12.org
26.3 Lipids
Lesson Objectives
- Describe the structure of a triglyceride.
- Distinguish between saturated and unsaturated fats.
- Describe the structure of a phospholipid and a lipid bilayer.
- Describe the structure and properties of waxes.
Vocabulary
- lipid
- triglyceride
- saturated fat
- unsaturated fat
- phospholipid
- wax
Check Your Understanding
Recalling Prior Knowledge
- What is an esterification reaction?
- Are polar molecules more soluble in polar solvents or nonpolar solvents?
Certain large molecules, known as fats, are an essential component of a healthy body, though excessive consumption
of fats is unhealthy. Fats are one member of a class of biological compounds known as lipids. In this lesson, you
will learn about the structure and function of various lipids.
Triglycerides
Lipidsare a class of water-insoluble compounds that includes oils, fats, and waxes. Oils and fats are based on the
same general structure, but fats are solids at room temperature, while oils are liquids. Butter is an example of a fat
that is derived from animals. Some oils include olive oil and canola oil, which are obtained from plants. Lipids are
an essential part of a healthy diet, though excess dietary fat can be harmful. Lipids store energy in the body and are
also needed to keep cell membranes healthy.
One type of lipid is called atriglyceride, which isan ester derived from the condensation reactions of three fatty
acid molecules with one molecule of glycerol.