To avoid being degraded by nuclear exonucleases, nascent transcripts, pre-mRNA-processing intermediates, and mature mRNAs in the nucleus must have their ends protected. Which of the following mechanism are present in the cell to protect mRNA from degradation?

I. The 5′ cap is protected because it is bound by a heterodimeric nuclear cap-binding complex (CBC), which protects it from 5′ exonucleases and also functions in export of the mRNA to the cytoplasm.

II. 5’-5’ phosphodiester bond in the cap of mRNA plays crucial role in protection

III. The 3′ end of a nascent transcript lies within the RNA polymerase and is thus inaccessible to exonucleases 

#Question id: 34171

#Unit 3. Fundamental Processes

#Question id: 24214

#Unit 1. Molecules and their Interaction Relevant to Biology

#Question id: 6968

#Unit 5. Developmental Biology

In Xenopus, the mesoderm moves in through the blastopore by rolling around the dorsal lip in a process called:

#Question id: 31154

#Unit 7. System Physiology – Animal

#Question id: 8680

#Unit 9. Diversity of Life Forms

Giardia intestinalis can cause disease in several different mammalian species, including humans. Giardia organisms (G. intestinalis) that infect humans are similar morphologically to those that infect other mammals, thus they have been considered a single species. However, G. intestinalis has been divided into different subgroups based on their host and a few other characteristics. In 1999, a DNA sequence comparison study tested the hypothesis that these subgroups actually constitute different species. The following phylogenetic tree was constructed from the sequence comparison of rRNA from several subgroups of G. intestinalis and a few other morphologically distinct species of Giardia. The researchers concluded that the subgroups of Giardia are sufficiently different from one another genetically that they could be considered different species

By examining the phylogenetic tree diagrammed in the figure above, what conclusion can you draw about the species G. microti?