What are macromolecules? Give examples.
Macromolecules (or biomacromolecules) are biomolecules found in the acid insoluble fraction of living tissues. These compounds have molecular weights in the range of ten thousand daltons and above.
Only three types of macromolecules are found in living systems: proteins, nucleic acids (RNA and DNA), and polysaccharides. Biomacromolecules are polymers made of building blocks. For example, proteins are heteropolymers made of amino acids, while nucleic acids are composed of nucleotides. Lipids are found in the macromolecular fraction due to their association with membranes, but they are not strictly macromolecules.
Explanation
The textbook clearly defines macromolecules as compounds in the acid insoluble fraction with molecular weights of ten thousand daltons or above. The three true macromolecules in living systems are proteins, nucleic acids, and polysaccharides. Lipids are mentioned separately because they appear in the macromolecular fraction due to membrane association but are not strictly macromolecules themselves.