Classically it was considered that each gene encoded one protein, the so-called one gene-one enzyme hypothesis. However, this model was modified as a result of the discovery of which of the following?
A) alternative splicing of primary transcripts to produce different forms of a protein
B) enhancer elements located upstream or downstream of the transcriptional promoter site in the DNA
C) oncogene products that act as transcription factors
D) transcription attenuation that regulates gene expression
E) variable number tandem repeats generating alternative processed genes during meiosis

Question

Quizplus · Accepted Answer

The discovery of alternative splicing showed that a single gene could produce multiple protein isoforms, modifying the one gene-one enzyme hypothesis.  The precise splicing outcome of a transcribed gene is controlled by complex interactions between cis-regulatory splicing signals and trans-acting regulators. Alternative splicing is a prevalent mechanism for generating transcriptome and proteome diversity. Alternative splicing can modulate gene function, affect organismal phenotype, and cause disease.

Classically It Was Considered That Each Gene Encoded One Protein