NANP Board Practice Exam

How are omega fatty acids numbered?

1. According to the carbon atom initiating the first double bond when counting from the carboxyl end

2. According to the carbon atom initiating the first double bond when counting from the methyl end of the molecule

3. According to the position of the first hydroxyl group

4. Based on the number of double bonds in the chain

The correct answer is: According to the carbon atom initiating the first double bond when counting from the methyl end of the molecule

Omega fatty acids are numbered based on the carbon atom that initiates the first double bond when counting from the methyl end of the molecule. This method of numbering is essential in understanding the structure and classification of fatty acids, particularly the omega-3 and omega-6 fatty acids, which play critical roles in health. For instance, an omega-3 fatty acid has its first double bond at the third carbon from the methyl end, which significantly influences its biological function. The other methods of numbering mentioned do not apply to Omega fatty acids specifically. Counting from the carboxyl end relates more to the systematic naming and identifying of fatty acids in a general context rather than the omega classification. The position of a hydroxyl group is not a defining factor for omega fatty acids, and double bond quantification alone does not provide the necessary context for their classification.