Draw the structure of docosahexaenoic acid (22:6Δ^{4,7,10,13,16,19}) and indicate what type of omega fatty acid it is.

• A. Omega-3 fatty acid.
• B. Omega-6 fatty acid.
• C. Omega-9 fatty acid.
• D. Omega-4 fatty acid.

Answer: (A)

Verified step by step guidance

1. Identify the basic structure of docosahexaenoic acid (DHA), which is a long-chain polyunsaturated fatty acid with 22 carbon atoms and 6 double bonds.
2. Understand the notation 22:6Δ4,7,10,13,16,19, which indicates a fatty acid with 22 carbons and double bonds at the 4th, 7th, 10th, 13th, 16th, and 19th carbon positions.
3. Draw the carbon chain of DHA, starting with the carboxyl group (COOH) at one end, followed by a chain of 22 carbon atoms.
4. Insert the double bonds at the specified positions (4, 7, 10, 13, 16, and 19) along the carbon chain, ensuring they are in the cis configuration, which is typical for naturally occurring unsaturated fatty acids.
5. Determine the type of omega fatty acid by counting the number of carbons from the methyl end (CH₃) to the first double bond. Since the first double bond is at the 3rd carbon from the methyl end, DHA is classified as an omega-3 fatty acid.