Spliceosome Assembly and Splicing of mRNA

The video explains the process of splicing in mRNA, focusing on the role of spliceosomes, which are protein-dependent complexes that facilitate the removal of introns and the joining of exons. It contrasts this with self-splicing introns, which do not require proteins. The video details the assembly of spliceosomes, involving small nuclear ribonucleoproteins (snRNPs) like U1, U2, U4, U5, and U6, and the ATP-dependent steps required for their function. The mechanism of splicing, including lariat formation and exon ligation, is described, highlighting the similarities with group 2 self-splicing introns. The video concludes with a brief mention of the next topic, polyadenylation of mRNA.

What is the main difference between self-splicing introns and those that require spliceosomes?

• Self-splicing introns require proteins.

• Spliceosomes do not require proteins.

• Self-splicing introns do not require proteins.

• Spliceosomes are not involved in splicing.

What are small nuclear ribonucleoproteins (snRNPs) primarily composed of?

• Only RNA

• Proteins and small nuclear RNA

• DNA and proteins

• Only proteins

Which snRNPs are involved in the initial complex formation during spliceosome assembly?

• U5 and U6

• U4 and U6

• U1 and U2

• U2 and U5

What is the role of ATP in spliceosome assembly?

• It hydrolyzes to release U1 and U4.

• It facilitates the binding of snRNPs.

• It is not required in spliceosome assembly.

• It provides energy for RNA synthesis.

What is formed when the adenosine 2' OH group reacts during splicing?

• A new exon

• A lariat structure

• A DNA strand

• A protein complex

What happens to the lariat intron after splicing is complete?

• It is degraded immediately.

• It remains attached to the exons.

• It forms a new RNA molecule.

• It is released after snRNPs dissociate.

Why do some introns require spliceosomes for splicing?

• They are already spliced.

• They are composed of DNA.

• They lack a secondary structure that favors self-splicing.

• They have a secondary structure that favors self-splicing.