gen-define-omega-3-fatty-acids-and-give-one-short-worked-example-153f

Define omega-3 fatty acids and give one short worked example.

# Omega-3 Fatty Acids **Definition:** Omega-3 fatty acids are essential polyunsaturated fatty acids characterized by having their first carbon-carbon double bond at the **third carbon (omega-3 position)** from the methyl (CH₃) end of the carbon chain. ## Worked Example: Alpha-Linolenic Acid (ALA) **Structure:** ALA has 18 carbons with 3 double bonds **Chemical formula:** C₁₈H₃₀O₂ **Notation:** 18:3 (n-3) **Counting from the omega end:** ``` CH₃-CH₂-CH=CH-CH₂-CH=CH-CH₂-CH=CH-CH₂-...-COOH ω1 ω2 ω3 ω4 ``` - Start counting from the methyl end (CH₃ = omega carbon) - ω1 = CH₃ - ω2 = CH₂ - ω3 = **CH** (first double bond starts here) Since the first double bond occurs at the 3rd carbon from the omega end, ALA is classified as an **omega-3** fatty acid. **Common sources:** Flaxseeds, chia seeds, walnuts, fish oil