As scientists were unraveling the mysteries associated with transcription and translation in eukaryotes, they discovered there was not a one-to-one correspondence between the nucleotide sequence of a gene and the base sequence of the mRNA it codes for. They proposed the genes-in-pieces hypothesis. How can the genes-in-pieces hypothesis be explained?
A) Introns are noncoding segments of DNA that are present in the initial transcript, but are removed by splicing.
B) Introns are noncoding segments of DNA that are not read or transcribed by RNA polymerase II.
C) Exons are noncoding segments of DNA that are not read or transcribed by RNA polymerase II.
D) Exons are noncoding segments of DNA that are present in the initial transcript but are removed by splicing.

Question

Quizplus · Accepted Answer

The genes-in-pieces hypothesis explains that eukaryotic genes are composed of both coding segments (exons) and noncoding segments (introns). Introns are transcribed along with exons to form the initial transcript, but then must be removed by splicing. This results in a final mRNA sequence that corresponds only to the exons. Therefore, introns are noncoding segments of DNA that are present in the initial transcript, but are removed by splicing.

As Scientists Were Unraveling the Mysteries Associated with Transcription and Translation