NANP Board Practice Exam

Which of the following fatty acids has a U-formation?

1. Cis fatty acids

2. Omega 9 fatty acids

3. Trans fatty acids

4. Carboxyl fatty acids

The correct answer is: Cis fatty acids

Cis fatty acids are characterized by their U-formation due to the configuration of the hydrogen atoms around the double bonds in their chemical structure. In cis fatty acids, the hydrogen atoms adjacent to the double bonds are on the same side, which results in a bend or kink in the carbon chain. This bend gives cis fatty acids a shape that resembles a "U." This U-shaped structure influences their physical properties, making them generally more fluid and less rigid than their trans counterparts. In contrast, trans fatty acids have a straight structure since the hydrogen atoms are positioned on opposite sides of the double bond. This linear formation leads to properties that resemble saturated fats, often causing them to be more solid at room temperature. Omega 9 fatty acids refer to a specific category based on their placement of double bonds and don't inherently describe the shape. Carboxyl fatty acids describes a functional group and doesn't relate to the specific spatial arrangement of the fatty acid chains.