Organic Chemistry MCAT Practice Exam

What effect do unsaturated fatty acids have on the fluidity of fats?

1. Increase viscosity

2. Decrease fluidity

3. Increase fluidity

4. No effect on fluidity

The correct answer is: Increase fluidity

Unsaturated fatty acids play a crucial role in influencing the fluidity of fats. The presence of double bonds in unsaturated fatty acids introduces kinks or bends in their carbon chains. This structural feature prevents the fatty acid molecules from packing closely together, resulting in a less ordered arrangement. As a result, the intermolecular forces between the fatty acid chains are reduced, allowing them to move more freely. This increased movement translates to a greater fluidity in the fatty acid configuration. Therefore, fats that contain a higher proportion of unsaturated fatty acids tend to be more fluid at room temperature compared to those composed primarily of saturated fatty acids, which can pack tightly and typically exhibit higher melting points. In summary, unsaturated fatty acids increase the fluidity of fats by disrupting tight packing due to their bent structure, leading to a more fluid state overall.