Question

7. In a mutant eukaryotic cell, the proteins involved in the addition of the 5’ cap of mRNA have been inactivated. Explain if this would affect the following and why it does (or doesn’t). a) The export of the mRNA from the nucleus to the cytosol?

b) Assuming the mRNA is in the cytosol, would this affect its translation?

Answer 1

7. In a mutant eukaryotic cell, the proteins involved in the addition of the 5’ cap of mRNA have been inactivated. Explain if this would affect the following and why it does (or doesn’t).

a) The export of the mRNA from the nucleus to the cytosol?

If the enzymes activating the 5’ capping are not activates, it would means that a mature mRNA transcript will not be formed. A mature mRNA transcript formations is required in the processing of mRNA. Here, if the mRNA will not be processed properly, there will not be exportation of the mRNA from the nucleus to the cytoplasm and thus, it will the nascent mRNA would be a target for degradation. Capping is required for the transcription export complex.

b) Assuming the mRNA is in the cytosol, would this affect its translation?

Assuming that even after mRNA capping, the mRNA is in the cytosol, it will still be prone to degradation. Also, this would consist of the THO complex. Since capping is not done, this complex would be responsible in elongation of the mRNA export and the transcription export. Yes, this would affect translation, since for translation to occur, there has to be elongation of the mRNA transcript and this elongation will not occur because of the absence of capping.