What type of fatty acids are characterized by the absence of double bonds?

Saturated fatty acids are defined by the absence of double bonds between the carbon atoms in their hydrocarbon chains. This saturation means that each carbon atom is fully "saturated" with hydrogen atoms. The molecular structure of saturated fatty acids allows them to pack tightly together, typically resulting in a solid form at room temperature. Examples of saturated fatty acids include stearic acid and palmitic acid.

In contrast, unsaturated fatty acids, which include both monounsaturated and polyunsaturated varieties, contain one or more double bonds in their structure. These double bonds create kinks in the fatty acid chains, preventing them from packing closely, which usually keeps them in a liquid state at room temperature. Trans fatty acids are a type of unsaturated fatty acid where the hydrogen atoms are on opposite sides of the double bond, but they still contain double bonds. Polyunsaturated fatty acids have two or more double bonds, further differentiating them from saturated fatty acids.

Thus, the defining feature of saturated fatty acids is indeed their lack of double bonds, confirming that they are characterized by this absence.