Multiple Choice
Draw the structure of docosahexaenoic acid (22:6Δ4,7,10,13,16,19) 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.
10. Lipids
Omega-3 Fatty Acids
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Assuming the standard shorthand naming system is used, which of the following is an omega-3 fatty acid?
a) 20:1Δ14
b) 18:3Δ9,12,15
c) 20:1Δ3,12
d) 18:2Δ9,12
A
20:1Δ14
B
18:3Δ9,12,15
C
20:1Δ3,12
D
18:2Δ9,12
Verified step by step guidance1
Understand the shorthand notation for fatty acids: The notation 'X:YΔa,b,c' represents a fatty acid with X carbon atoms, Y double bonds, and double bonds located at carbon positions a, b, and c from the carboxyl end.
Identify the omega-3 fatty acid: Omega-3 fatty acids have their first double bond at the third carbon from the methyl end (omega end) of the fatty acid chain.
Convert the shorthand notation to identify the omega position: For each option, subtract the position of the first double bond from the total number of carbons and add 1 to find the omega position.
Analyze option b) 18:3Δ9,12,15: Subtract 15 (the position of the first double bond) from 18 (total carbons) and add 1, resulting in 4, indicating it is an omega-3 fatty acid.
Verify other options: Repeat the conversion for other options to confirm they do not meet the omega-3 criteria, ensuring option b) is the correct choice.
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Omega-3 Fatty Acids practice set
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