Which of the following is NOT a macromolecule? (A) Carbohydrates (B) Nucleic acids (C) Organelles (D) Proteins (E) Lipids
The Correct Answer and Explanation is :
The correct answer is (C) Organelles.
Explanation:
Macromolecules are large, complex molecules essential for life. They are typically composed of smaller subunits linked together in a specific arrangement. The four major classes of macromolecules are carbohydrates, nucleic acids, proteins, and lipids. Each serves vital functions in biological systems:
- Carbohydrates: Composed of sugar monomers (e.g., glucose), they serve as a primary energy source and structural components (e.g., cellulose in plants).
- Nucleic Acids: DNA and RNA are made up of nucleotide monomers. They store and transmit genetic information.
- Proteins: Built from amino acid monomers, proteins perform a wide range of functions, including catalyzing biochemical reactions (enzymes), providing structural support, and aiding in cell signaling.
- Lipids: Although not polymers, lipids (like fats, oils, and steroids) are considered macromolecules because of their large size and essential biological functions, such as energy storage and forming cell membranes.
Why Organelles Are Not Macromolecules:
Organelles are subcellular structures found in eukaryotic cells, such as the nucleus, mitochondria, and lysosomes. They are made up of various macromolecules working together to perform specific tasks. For example:
- The cell membrane of an organelle is composed of lipids and proteins.
- The genetic material within the nucleus is nucleic acids.
Since organelles are made up of macromolecules but are not themselves macromolecules, they are not classified in the same category. Instead, organelles are functional units of cells, while macromolecules are the building blocks that compose organelles and other cellular components.
Summary:
Organelles (C) are not macromolecules but assemblies of various macromolecules organized to perform distinct cellular functions. The other options represent true classes of macromolecules.