Question

place the stages of eukaryotic gene splicing in order from beginning to end.

rank the options below.

mrna is exported from the nucleus
intron are looped into lariat structures
exons are joined
mrna is cut
spliceosomes recognize the intron-exon junction

Explanation:

Identify the sequence of eukaryotic gene splicing

1. Spliceosomes recognize the intron-exon junction: The spliceosome machinery (snRNPs) binds to specific consensus sequences at the 5' splice site and branch point.
2. mRNA is cut: The 5' end of the intron is cleaved from the upstream exon.
3. Introns are looped into lariat structures: The cleaved 5' end of the intron covalently bonds to an adenine residue at the branch site, forming a lariat loop, followed by cleavage at the 3' splice site.
4. Exons are joined: The free 3' hydroxyl group of the upstream exon attacks the 5' phosphate of the downstream exon, ligating them together.
5. mRNA is exported from the nucleus: The mature, spliced mRNA is transported through nuclear pores into the cytoplasm for translation.

Answer:

1. Spliceosomes recognize the intron-exon junction
2. mRNA is cut
3. Intron are looped into lariat structures
4. Exons are joined
5. mRNA is exported from the nucleus