- Lipids
A Saturated Fatty Acid ( left) and a Poly-unsaturated Fatty Acid (right)

The difference in the structure between saturated and. unsaturated fatty acids gives them different chemical properties. Saturated fatty acids can align close together and are usually solid at room temperature (aka Fat). Because they are "bent", unsaturated fatty acids are less able to interact and are liquid at room temperature (oils).

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