Question

What is the "one gene-one enzyme theory"? How was it developed (i.e. what experiments did Beadle and Tatum do)? Why do we now call it the "one gene-one polypeptide theory"? How does alternative splicing change this theory?

Answer 1

According to one gene one enzyme theory which was discovered by beadle and tatum, single gene is responsible for the the single enzyme produced during any metabolic pathway.

They had done their experiment on neurospora crassa, a bread mold. They had given mutations to the mold by X rays and then grown the mutant cells on minimal media.

Results of their experiments were that the mutant cells did not grow on minimal media but can grow on complete media.

This mean that the mutation caused some defect on the gene responsible for the production of enzyme of metabolic pathway and thus they proved that the one gene is responsible for the production of one enzyme.

Later on it was confirmed that the enzymes could have several polypeptide chain and one gene could not produce several polypeptide, then the theory was revised to one gene one polypeptide.