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Help me number 5 and 8 5. What transcript region usually begins with a methylate

ID: 190840 • Letter: H

Question

Help me number 5 and 8

5. What transcript region usually begins with a methylated guanosine? a) 5 Cap b) 3' PolyA tail c) Exon d) Intron e) Promoter 6, Which type of RNA undergoes "typ e I splicing" to produce mature transcripts? a tRNA b) rRNA c) mRNA d) snRNA e) miRNA 7. Which RNA polymerase usually starts transcription upstream of its promoter? c Pol III a) Pol I b) Pol I d) All start sites are downstream of promoter regions 8. Which of the following processes occurs in prokaryotes? a) 7-methylguanosine capping at the 5 end of mRNA b) polyadenylation at the 3' end of mRNA c) removal of intron sequences by spliceosome complex d) none of the above e) all of the above

Explanation / Answer

5. a. 5' cap

The 5' cap of an mRNA consists of a guanosine methylated on the 7 position to prevent degradation by exonucleases, promote translation and regulate nuclear export.

8. d. none of the above

The above actions are found only in eukaryotes, because the mRNA doesn't leave the transcription site, and translation begins almost immediately as the mRNA is formed. In eukaryotes, the mRNA has to leave the nucleus, so it needs higher stability. Splicing is also not found in prokaryotes has they usually have polycistronic mRNAs.