In an experiment investigating eukaryotic gene expression, researchers hybridized single-stranded genomic DNA with either newly transcribed pre-mRNA or fully processed mature mRNA from the same gene. Under an electron microscope, the pre-mRNA forms an uninterrupted hybrid duplex with the DNA strand, whereas the mature mRNA forms hybrid segments interrupted by several single-stranded DNA loops. Which biological process directly accounts for the formation of these DNA loops in the mature mRNA hybrid?

A) Addition of the 5′ 7-methylguanosine cap and 3′ poly-A tail that physically blocks internal base pairing

B) Excision of non-coding introns from the pre-mRNA by the spliceosome prior to hybridization

C) Degradation of coding exons by cytoplasmic ribonucleases after mRNA transport out of the nucleus

D) Formation of transient DNA replication bubbles that selectively open along the coding region

RNA processing Transitional Reasoning Practice

Biology · Molecular Genetics · Biology · Gene Expression

1 Biology practice questions on RNA processing. Questions that build towards applied reasoning.

Layout:

Choose how questions appear in the preview and test.

Preview the questions below, then start to answer and see your results.

Answers and step-by-step solutions appear after you finish the test.