Final answer:
The properties of side chains that determine their character include molecular weight, charge, and hydrophobicity, which collectively influence the amino acids and protein's structure and function.
Step-by-step explanation:
The major properties of side chains that determine their character are molecular weight, charge, and hydrophobicity. These properties affect the amino acids' size, shape, solubility, and ionization properties, which in turn impact the structure and functionality of proteins. Molecular weight affects how the side chains contribute to the overall mass of the amino acid, while charge determines how side chains interact with each other and with the surrounding environment, influencing the protein's structure and activity. Hydrophobicity, or how water-loving or water-fearing a side chain is, also greatly shapes protein folding and stability by driving hydrophobic side chains to hide from water within the protein's interior, or allowing hydrophilic side chains to interact with aqueous surroundings.