Suppose the 3' splice site is mutated from AGG to ACG. Predict the consequence of this mutation. Choose one: A. Splicing would occur as normal because this splice site is less important than the 5' splice site. B. Splicing would occur as normal but there would be a point mutation in the mRNA and final protein sequences. C. Splicing would not begin if the 3' splice site is altered. D. Splicing would begin but not be properly completed if the 3' splice site is altered.

Solution :

The correct order of the RNA splicing is :

1. The BBP and the U2AF is to bind the A in branch point site in the intron, but the U1snRNP binds the 5' splice site.

2. U2snRNP helps to bind the branch point site while U4/U6 and the U5snRNP binds the 5' slice site.

3. 5' end of intron binds branch point adenine and forms a lariat.

4. Conserved adenine in branch point site attacks 5' splice site thus cutting the RNA at 5' splice site.

5. Lariat is released and then degraded.

6. The 3' end of first exon interacts with 3' splice site and forms a new bond in the sugar phosphate backbone.

When the 3' splice is altered, then the splicing begins but are not properly completed due to the altered activity of the full introns that will be present in mRNA.

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