Question

Scientists once believed that each gene can encode a single polypeptide. We now know that __________ and ___________ allow a single gene to encode more than one polypeptide.

1) transcription; translation
2) polyadenylation; RNA transport
3) DNA methylation; chromatin condensation
4) alternative processing; RNA editing
5) gene silencing; RNA interference

Answer 1

The correct answer is that alternative processing and RNA editing allow a single gene to give rise to multiple polypeptides. This is made possible by the processes of alternative splicing and post-transcriptional modifications of mRNA.

Step-by-step explanation:

Scientists once believed that each gene can encode a single polypeptide. We now know that alternative processing and RNA editing allow a single gene to encode more than one polypeptide. Therefore, the correct answer is alternative processing; RNA editing.

During transcription, a segment of DNA is copied into mRNA. This mRNA may undergo several modifications before it is translated into a polypeptide. In eukaryotic cells, mRNA is edited through a process known as alternative splicing, whereby introns are removed and exons can be pieced together in different ways. This means that a single gene can give rise to multiple different mRNA transcripts that will result in different polypeptides once translated. RNA editing further alters mRNA after transcription and can lead to changes in the protein sequence that were not encoded by the DNA, providing an additional level of diversity in the proteins a single gene can produce.