What is the primary characteristic of macromolecules in supramolecular complexes?

The primary characteristic of macromolecules in supramolecular complexes is that they maintain individual identities while forming complexes. This means that even though these macromolecules interact and associate to form larger assemblies, they do not lose their distinct identities or functions. Each component retains its functional role, which is crucial for the complex's overall functionality.

Supramolecular complexes often arise from non-covalent interactions, such as hydrogen bonding, ionic interactions, and hydrophobic effects, which facilitate reversible interactions. These interactions allow macromolecules to come together to form dynamic structures, where they can easily separate and reassociate without undergoing permanent changes. This property is essential for processes such as cellular signaling, structural organization in cells, and the assembly of biomolecular machines.

In contrast, the other options do not reflect the nature of supramolecular complexes accurately. The formation of irreversible bonds is not characteristic of these complexes, which are typically based on reversible interactions. Furthermore, not all macromolecules involved in supramolecular complexes are proteins; they can also include nucleic acids and polysaccharides. Lastly, macromolecules in these complexes are not uniform in size and structure; often, they vary significantly, contributing to the complexity and functionality of the assembly.