Which macromolecule is composed of a linear sequence of amino acids?

• A. Polypeptide
• B. Nucleic acid
• C. Carbohydrate
• D. Lipid

Answer: (A)

The correct answer is a polypeptide, which is a macromolecule formed from a linear sequence of amino acids linked together by peptide bonds. This sequence of amino acids defines the specific structure and function of the polypeptide, which can fold into complex three-dimensional shapes to become functional proteins. The order of amino acids in a polypeptide is encoded by the genetic information in DNA and is crucial for the protein's activity.

In contrast, nucleic acids, such as DNA and RNA, consist of sequences of nucleotides, which are different from amino acids. Carbohydrates are made up of sugar molecules linked together, forming polysaccharides, while lipids are primarily composed of fatty acids and glycerol, lacking the linear sequences characteristic of amino acids. Each of these macromolecules has distinct structures and functions, making polypeptides unique due to their specific linear arrangement of amino acids.