26.3. Lipids http://www.ck12.org
26.3 Lipids
Lesson Objectives
- List various classes of lipids and explain their functions.
- Describe the digestion of lipids in the small intestine.
- List various classes of lipoproteins and explain their functions.
- Describe the utilization of stored triglycerides for biochemical energy.
- Explain the relationship between cholesterol and heart disease.
Lesson Vocabulary
- cholesterol
- chylomicron
- fatty acid
- glycerol
- lipid
- lipoprotein
- steroid
- triglyceride
Check Your Understanding
Recalling Prior Knowledge
- What is the structure of a carboxylic acid?
- What is the structure of an ester?
- What do enzymes do?
Classes of Lipids
In the lesson on carbohydrates, we saw that monosaccharides all have a similar structure, but with slight variations.
Many monosaccharides can then be linked together to form long polysaccharide chains. Similarly, amino acids
all share some of the same structural features, and linking many amino acids together results in the formation of
proteins. In contrast, lipids constitute a much broader class of compounds. Alipidis a biological molecule that is
soluble in nonpolar solvents. This also means that lipids are generally not very soluble in polar solvents, such as
water. Because of this characteristic, lipids in the body generally cluster together in order to minimize contact with
water, and transportation of lipid molecules throughout the body requires that they be reversibly attached to various
transport proteins. A lipid bonded to a protein is referred to as alipoprotein.