The correct answer is a. Exon/intron boundaries are typically characterized by a 5' GU splice junction and a 3' AG splice junction.
Explanation:
Splicing is the process in which the non-coding introns are removed from the mRNA and only coding sequences remains in mRNA.
The splicing of introns depends on the recognition of splice site pair. Usually, 5'-GU-3' is 5' splice site and 5'-AG-3' is 3' splice site which makes the boundary of introns/exons and these two nucleotides are important to recognize the introns.
There are some additional conserved sequence at these two splice site which help in recognition of introns. First, a lariate structure is formed when 5'-GU-3' is cleaved and joined to the branch point that is present near 3' slice site. Then 3' splice site is cleaved which releases the intron. Therefore the correct answer is a.
An introduced species, alien species, exotic species, adventive species, immigrant species, ... Non-native species can have various effects on the local ecosystem. ... Some species have been introduced intentionally to combat pests
