NEET BIOLOGY

Detailed explanation-1: -Introns are removed from primary transcripts by cleavage at conserved sequences called splice sites. These sites are found at the 5′ and 3′ ends of introns. Most commonly, the RNA sequence that is removed begins with the dinucleotide GU at its 5′ end, and ends with AG at its 3′ end.

Detailed explanation-2: -Introns are removed from the pre-mRNA by the activity of a complex called the spliceosome. The spliceosome is made up of proteins and small nuclear RNAs (snRNAs) that associate to form protein-RNA enzymes called small nuclear ribonucleoproteins or snRNPs (pronounced SNURPS).

Detailed explanation-3: -For those eukaryotic genes that contain introns, splicing is usually needed to create an mRNA molecule that can be translated into protein. For many eukaryotic introns, splicing occurs in a series of reactions which are catalyzed by the spliceosome, a complex of small nuclear ribonucleoproteins (snRNPs).

Detailed explanation-4: -Introns are intervening sequences within a pre-mRNA molecule that do not code for proteins and are removed during RNA processing by the spliceosome before the mRNA is exported to the cytoplasm.