Question

______ groups are the "acid" part of amino acids and fatty acids. a. Hydroxyl \((-\mathrm{OH})\) b. Carboxyl \((-\mathrm{COOH})\) c. Methyl \(\left(-\mathrm{CH}_{3}\right)\) d. Phosphate \(\left(-\mathrm{PO}_{4}\right)\)

Short answer

The correct answer is b. Carboxyl ext{(-COOH)}.

Step-by-step solution

Understand the Question

The question is asking which group of atoms, referred to as the 'acid' part, is found in both amino acids and fatty acids. Each option provided represents a different functional group in organic chemistry.

Identify the Acidic Group in Amino Acids

Amino acids are organic compounds that contain both an amino group ext{(-NH}_2 ext{)} and a carboxyl group ext{(-COOH)}. The carboxyl group is responsible for the acidic properties of amino acids.

Identify the Acidic Group in Fatty Acids

Fatty acids are long-chain hydrocarbons with a terminal carboxyl group ext{(-COOH)}. This carboxyl group makes them acidic, hence they're called 'acids.'

Compare with Given Options

The options provided are hydroxyl ext{(-OH)}, carboxyl ext{(-COOH)}, methyl ext{(-CH}_3 ext{)}, and phosphate ext{(-PO}_4 ext{)}. As identified in Steps 2 and 3, the carboxyl group ext{(-COOH)} is common to both amino acids and fatty acids and is referred to as the 'acid' part.

Key concepts

Carboxyl group

The carboxyl group, often represented as \((-\text{COOH})\), is a critical functional group in organic chemistry. It's known for imparting acidic properties to the molecules it is part of. This group consists of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group \((-\text{OH})\).
The presence of the carboxyl group in a molecule enables it to donate a proton \((H^+)\), resulting in its acidic nature.
This proton donation is a key characteristic that defines acids in organic chemistry.

• The carboxyl group is crucial in organic acids, such as amino acids and fatty acids.
• It is responsible for the molecule's capability to participate in reactions such as esterification and amidation.
• Its double-bonded oxygen increases the molecule's polarity, influencing how the molecule interacts with other compounds.

This group plays a vital role in metabolic pathways, helping synthesize more complex molecules essential for life.

Amino acids

Amino acids are the building blocks of proteins, and they play a vital role in biochemistry. Each amino acid features at least one amino group \((-\text{NH}_2)\) and a carboxyl group \((-\text{COOH})\), making them distinctive.
This combination is fundamental to their function in living organisms.

• The carboxyl group contributes to the acidic nature of the molecule, allowing it to participate in peptide bond formation. This bond formation is essential in creating proteins.
• Amino acids also have a side chain specific to each type, influencing their properties and roles.
• Amino acids are categorized based on the nature of their side chains: nonpolar, polar, acidic, and basic.

These compounds are influential in numerous biological processes, including enzyme function and cell signaling.
Without amino acids, essential bodily functions such as tissue repair and nutrient transportation would not occur.

Fatty acids

Fatty acids are long hydrocarbon chains with a terminal carboxyl group \((-\text{COOH})\), contributing to their classification as acids.
These molecules are fundamental in the composition of fats and oils, serving as significant energy sources.

• The carboxyl group imparts the acidic properties necessary for emulsification and the synthesis of various lipids.
• Fatty acids can be saturated or unsaturated, with the distinction based on the presence of double bonds within the hydrocarbon tail.
• They are key components in cellular membranes, influencing membrane fluidity and permeability.

Through beta-oxidation, fatty acids are broken down into acetyl-CoA, which enters the citric acid cycle to release energy.
This makes them not only building blocks for more complex lipids but also integral in energy storage and production in the body.