What two chemical groups are found at the end of either side of the fatty-acid carbon chain?
The correct answer and explanation is:
The two chemical groups found at the end of either side of the fatty acid carbon chain are the carboxyl group (-COOH) at one end and the methyl group (-CH3) at the other end.
Carboxyl Group:
The carboxyl group is a functional group consisting of a carbonyl group (C=O) attached to a hydroxyl group (-OH). It is located at the alpha or head end of the fatty acid molecule. The presence of this group makes the fatty acid acidic. The carboxyl group is responsible for the fatty acid’s ability to react with other molecules. In aqueous solutions, the carboxyl group can release a proton (H+), turning the fatty acid into its ionized form (carboxylate anion, -COO−) in basic conditions. This makes the carboxyl group highly reactive and crucial in the formation of various biochemical compounds, such as triglycerides and phospholipids, which are essential components of cell membranes.
Methyl Group:
The methyl group is a group of one carbon atom attached to three hydrogen atoms (-CH3). It is located at the omega or tail end of the fatty acid chain. Unlike the carboxyl group, the methyl group is non-polar and hydrophobic. The presence of the methyl group makes the fatty acid chain largely insoluble in water. The methyl end of the fatty acid is involved in hydrophobic interactions, which are critical for the formation of biological membranes, like lipid bilayers, where fatty acids are arranged to hide their hydrophobic tails from the aqueous environment.
These two groups—carboxyl at the head and methyl at the tail—give the fatty acid its characteristic properties, with one end being polar and hydrophilic (attracted to water) and the other being non-polar and hydrophobic (repelling water). This unique structure allows fatty acids to participate in various biological functions, such as energy storage, membrane formation, and signaling within cells.