Question

Which of the following occurs ONLY in eukaryotic cells and NOT in prokaryotic cells?

		RNA polymerase binds to the DNA template at the promotor sequence of the gene
		RNA polymerase is capable both of unwinding and separating the DNA helix - hence displaying part of the DNA template for transcription - and of catalyzing the formation of phosphodiester bonds.
		RNA polymerase pairs up Uracil (U) in the elongating RNA strand with Adenine (A) in the DNA template
		RNA polymerase pairs up Thymine (T) in the elongating RNA strand with Adenine (A) in the DNA template
		Spliceosomes play an important role in the post-transcription editing of the RNA molecule

Answer 1

I solved this question in detail about splicing and Exon and intron and also mechanism..
Page No.: Date : 1 Ans obviously its answer is last noire Splice o some plays an important role in post-transcription editing of the RA It is so simple to understand that eukaryotes have interrupted gene it means it has exon as well as in tron g Here in Eukaryotes Exon is functional and intron is non- functional So soliceosone occur in Eukaryotes Here meaning of spliceosome 2 n a splicing w some means body be It is a process in which Non functional gene is cut outa o Pre mRNAS - splicing MRNA PETETE LU Nuclear pre-mRNA splicing is catalyzed by the spliceosome a multi-megadalton ribonucleo. protein CRNP) complex. Both the conformation land -combosition of the spliceosome are highly dynamic, affording the splicing machinery its accuracy and at the same time flexibility two unique spliceosomes coexist in most eukaryotes: the Oor dependent spliceesome which catalyzes the removal of type introns, and the less abundant ou debendent Iskliceosome, which is present in only a subset of eukaryotes and splices the rate

Page No: Date: OH group of the branch adenosine class of introns. Nuclear Pre-MRNA introns are removed two consecutive transesterification reactions first, the rol group of the bi fot the intron carries out a nucleophilic attack on the siss. This results in cleavage at this site and ligation of the s'end of the intros on the branch adenosine, forming a tariat structure not Second, the ass is attacked by the 3 oH group of the s'exon, leading to the ligation of the s'& zl exons (forming the mRNA a Release of the intron. The intermediate and products of pre-mRNA Sblicing are similar to those generated during the removal of group I self splicing introns not This similarly led to the hypothesis that catalysis of pre-mRNA splicing is also RNA based Like wise similar to group it self splicing fintrons it was recently shown that, under the appropriate conditions, the chemical steps of l of nuclear pre-mRNA splicing are preversible which further emphasizes mechanism similarities between two system These studies also underscore the dynamic nature of the Aplicesome during the Catalytic. phase of splicing