Handout 7

Comparing and contrasting Tazswana’s pre-mRNA intron to the normal intron, answer the following questions (use terms such as 5’ splicing site, 3’ splicing site, etc.)
1. How is Tazswana’s intron similar to the normal β-globin pre-mRNA?
Tazswana’s intron is similar in that they both contain the same starting, close to the 5’ splicing site, and ending, close to the 3’ splicing site, nucleotides GU and CAG.

2. How is Tazswana’s intron different from the normal β-globin pre-mRNA?
Tazswana’s intron is different in that the central nucleotides are different: Tazswana with CAGNNNNGU and normal mRNA with AGNNNNNUU. The nucleotides in bold are also different.

3. Assuming that the cellular splicing machinery will “cut” at the GU 5’ splicing site and the very next 3’ splicing site, CAG, predict how Tazswana’s pre-mRNA will be processed into mRNA. Show the resulting mRNA from this process.
Tazswana’s pre-mRNA will be processed into a normal mRNA if the splicing occurs in the respective GU 5’ Splicing site and CAG 3’ splicing site. The resulting mRNA would be AGG, exon 2 with exon 3 and no intron involved.

4. If the doctors could somehow trick the splicesome (the cell’s machinery that splices pre-mRNA into mRNAs) into ignoring Tazswana’s extra splicing sequence, could she have a normal β-globin mRNA? Explain why or why not.
Yes, if Tazswana’s extra splicing sequence could be ignored and the normal sequence continues, then she could have a normal β-globin mRNA. Ignoring the extra sequence would cause the natural machinery to splice in the correct place making a normal mRNA that would carry out its function normally.