In regard to excision of introns and splicing of exons in a primary RNA transcript,the spliceosome is made up of:

Question

Quizplus · Accepted Answer

The spliceosome is a complex made up of small nuclear ribonucleoprotein particles (snRNPs) that are composed of both RNA and protein subunits. Therefore, choice B is the correct answer. Choice A is incorrect because although noncoding RNAs are involved in other aspects of gene expression, they are not specifically involved in excision of introns and splicing of exons. Choice C is incorrect because histone proteins and DNA are involved in the packaging of DNA into chromatin, but not directly in the excision and splicing of mRNA. Choice D is incorrect because ribosomal RNA is involved in protein synthesis in the cytoplasm, and not in the processing of primary RNA transcripts.

In Regard to Excision of Introns and Splicing of Exons