Concept 5.3: Lipids are a diverse group of hydrophobic molecules

Flashcards from Concept 5.3 of Pearson's Campbell Biology, Twelfth Edition.

Lipids

The one class of biological molecules that do not include true polymers, unified by their poor mixture with water

• Consist mostly of hydrocarbon regions

• Biologically important types include fats, phospholipids, and steroids

Fats

Type of lipid constructed from glycerol and fatty acid molecules

Glycerol

A three-carbon alcohol with a hydroxyl group attached to each carbon

Saturated fats

Fats with the maxiumum number of hydrogen atoms and no double bonds

• Solid at room temperature

• Includes most animal fats

• Can cause cardiovascular disease through plaque deposits

Unsaturated fats

Fats with one or more double bonds and fewer hydrogen atoms

• Liquid at room temperature

• Includes plant fats and fish fats

Hydrogenation

The process of converting unsaturated fats to saturated fats by adding hydrogen

• This leads to trans fats with double bonds in vegetable oils that can contribute to cardiovascular disease

Adipose cells

Cells used for storage in humans and other mammals that cushion the body and organs

Phospholipid

Type of lipid with two fatty acids and a phosphate group attached to glycerol

• Fatty acid tails are hydrophobic, phosphate heads are hydrophilic

• In water, they assemble a bilayer with the tails toward the interior as a boundary between cells and their environment

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings

Cholesterol

A type of steroid from which animal cell membranes and other steroids are synthesized

• High levels of this may contribute to cardiovascular disease