George Beadle and Edward Tatum used mutant strains of Neurospora to formulate the one-gene-one-enzyme hypothesis. Researchers la
ter updated this hypothesis to propose that one gene encodes one polypeptide because proteins can have multiple subunits. Consider a heterodimeric protein. How many genes are required to form this protein? (A) two
(B) four
(C) six
(D) three
(E) one
A heterodimeric protein consists of two polypeptides (a polypeptide is a chain of amino acids) that differ in amino acid composition, number or order in the chain sequence. Each polypeptide makes a different subunit of the protein.
One gene encodes one polypeptide, so if the protein has two different polypeptides, two genes are required to form this protein.
