AP BIOLOGY

Detailed explanation-1: -During splicing, coding-regions of mRNA (exons?) are kept and non-coding regions of mRNA (introns?) are cut out and removed. mRNA Splicing is an important step in the transcription process, as without removing the introns the correct protein cannot be formed.

Detailed explanation-2: -The hnRNA, which is longer than mRNA, contains both m6Ap and caps but 4-6 times as many m6Ap residues per chain. In addition, nuclear molecules contain T2 RNA ase-resistant, methyl-labeled oligonucleotides ("di-” and “tri-” nucleotides) which are not found in mRNA.

Detailed explanation-3: -In most cases, splicing removes introns as single units from precursor mRNA transcripts. However, in some cases, especially in mRNAs with very long introns, splicing happens in steps, with part of an intron removed and then the remaining intron is spliced out in a following step.

Detailed explanation-4: -Introns are removed from hnRNA by the process of splicing to create functional mRNAs which comprise just the exon sequences of the gene in question.