AP BIOLOGY

Detailed explanation-1: -Nuclear pre-mRNA splicing is catalyzed by the spliceosome, a multi-megadalton ribonucleoprotein (RNP) complex.

Detailed explanation-2: -Splicing of a pre-mRNA molecule occurs in several steps that are catalyzed by small nuclear ribonucleoproteins (snRNPs). After the U1 snRNP binds to the 5′ splice site, the 5′ end of the intron base pairs with the downstream branch sequence, forming a lariat.

Detailed explanation-3: -A large protein complex known as the spliceosome controls mRNA splicing. The spliceosome is composed of particles made up of both RNA and protein. These particles are called small nuclear ribonucleoprotein or snRNPs (pronounced “snurps”) for short.

Detailed explanation-4: -Splicing of nuclear pre-mRNAs involves a stepwise assembly of five (U1, U2, U4, U5, and U6) small nuclear ribonucleoproteins (snRNPs) and several other proteins onto a pre-mRNA to form a large complex called the spliceosome (10, 91, 108).

Detailed explanation-5: -In RNA splicing, specific parts of the pre-mRNA, called introns are recognized and removed by a protein-and-RNA complex called the spliceosome. Introns can be viewed as “junk” sequences that must be cut out so the “good parts version” of the RNA molecule can be assembled.