[Campbell Biology P.428] Recent genomic discoveries about noncoding RNAs ncRNAs have led to ... | Practice Question

Recent genomic discoveries about noncoding RNAs ncRNAs have led to a significant shift in biological understanding. Which of the following statements is supported by the text regarding these discoveries?

  • A: The human genome consists primarily of protein-coding DNA, with only a negligible fraction dedicated to non-protein-coding RNA genes.
  • B: The concept of 'junk DNA' has been fully validated, confirming that most of the transcribed genome without protein-coding function is indeed non-functional.
  • C: Approximately 75% of the human genome is transcribed at some point, and a significant portion of this transcribed RNA consists of non-protein-coding RNAs, challenging previous assumptions about gene function.
  • D: MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) primarily regulate gene expression by modifying chromatin structure, but have little to no effect on mRNA translation.

Explanation

The text states that 'a massive study showed that roughly 75% of the human genome is transcribed at some point in any given cell' and that 'at least some of the genome is transcribed into non-protein-coding RNAs'. It also mentions challenging the 'junk DNA' concept and a 'major shift in thinking' about RNA roles. This supports option C. Option A is incorrect because only 1.5% is protein-coding DNA. Option B is incorrect as 'junk DNA' concept is being challenged. Option D is incorrect as the text states ncRNAs regulate 'mRNA translation and chromatin modification'.