Splicing Mechanisms and Functions

The video tutorial covers the basics of splicing in eukaryotic cells, explaining the removal of introns and joining of exons to form mature mRNA. It details the splicing mechanisms for group 1 and group 2 introns, including self-splicing and spliceosome-mediated processes. Key terms such as splice sites, exons, and introns are defined, and the roles of snRNA and snRNPs in spliceosome-mediated splicing are discussed.

What is the primary difference between exons and introns in pre-mRNA?

• Both exons and introns are non-coding sequences.

• Both exons and introns are coding sequences.

• Exons are coding sequences, while introns are non-coding sequences.

• Exons are non-coding sequences, while introns are coding sequences.

What is the role of the 5' splice site in splicing?

• It is where the intron is joined to the exon.

• It is where the exon is joined to the intron.

• It is the site where the phosphodiester bond is formed.

• It is the site where the phosphodiester bond is broken.

How does the group 1 intron splicing mechanism differ from other splicing mechanisms?

• It requires external proteins for splicing.

• It uses an adenine residue within the sequence.

• It uses a free guanine nucleotide for splicing.

• It involves a spliceosome complex.

What is unique about the splicing of group 2 introns?

• It uses a free guanine nucleotide.

• It only occurs with the help of proteins.

• It can occur through self-splicing or with a spliceosome.

• It does not involve any RNA.

What is the function of the spliceosome complex in splicing?

• It assists in the self-splicing of introns.

• It adds additional nucleotides to the mRNA.

• It breaks down introns into smaller pieces.

• It facilitates the joining of exons by removing introns.

Which snRNA is the first to bind during the spliceosome-mediated splicing process?

• U2

• U6

• U4

• U1

What happens when U2 binds to the adenine at the branch site?

• The adenine bulges out.

• The adenine is replaced by guanine.

• The adenine forms a new bond with U1.

• The adenine is removed.

What is the role of U6 snRNP in the spliceosome complex?

• It forms the lariat structure.

• It interacts with U2 and displaces U1.

• It initiates the splicing reaction.

• It binds to the 3' splice site.

What is the lariat structure in splicing?

• A loop formed by the 5' splice site and adenine.

• A bond between two exons.

• A complex of proteins and RNA.

• A sequence of nucleotides added to mRNA.

How many snRNA are involved in the spliceosome complex?

• Three

• Four

• Five

• Six