<prompt> Which one of the following can be a homologous substitution for isoleucine in a protein sequence?MethionineAspartic acidValineArginine  <response>: Ans. C. ValineHomologous substitutions are those which dont affect the function. Valine is an amino acid with aliphatic side chain and isoleucine also has aliphatic side chaina. Methionine is a Sulphur containing amino-acid and will not be a homologous substitution for isoleucineb. Aspartic acid has an acidic side chain and will not be a homologous substitution for isoleucinec. Valine has aliphatic side chain and will be a homologous substitution for isoleucined. Arginine has a basic side chain and will not be a homologous substitution for isoleucine 