帮我做一题分子生物学题目?我会再申几个号给你加分的!You have isolated a new strain of an E.coli-like bacteria from hospital patients.Upon sequencing the genome,you discover that this bacteria has a group of about 30 genes,absent

帮我做一题分子生物学题目?我会再申几个号给你加分的!You have isolated a new strain of an E.coli-like bacteria from hospital patients.Upon sequencing the genome,you discover that this bacteria has a group of about 30 genes,absent
帮我做一题分子生物学题目?我会再申几个号给你加分的!
You have isolated a new strain of an E.coli-like bacteria from hospital patients.Upon sequencing the genome,you discover that this bacteria has a group of about 30 genes,absent from the standard lab strains,that you suspect are involved in pathogenesis(发病机理).You initiate a project to understand the expression and function of these genes.
By comparing mRNA sizes with the DNA sequence,you realize that one of these genes,pukC,appears to contain an intron.Since bacteria lack the spliceosome components found in higher cells,you hypothesize that you have isolated a new self-splicing intron.
Sequence analysis of the pukC intron failed to reveal clear homology to either the group I or group 2 self-splicing intron families.
To study the mechanism of splicing you clone the pukC gene on to a plasmid behind a good promoter.This construct allows you to synthesize the pukC pre-mRNA using in vitro transcription.When you run the products of this first transcription experiment on a gel,you see RNA molecules with lengths suggesting that splicing is occurring (although very slowly) during the transcription reactions.
Question 1:Given this result,suggest a modification of the in vitro
reaction used above that could give a quick indication of whether the pukC intron uses a mechanism similar to the group I or similar to the group II introns.
Question 2:Now describe a more definitive experiment that will allow
you to show that the pukC intron uses either a group I or group II-like
mechanism.What results do you expect to observe for each of the two
mechanisms?
可以用汉语吗？我看不懂这个!

帮我做一题分子生物学题目?我会再申几个号给你加分的!You have isolated a new strain of an E.coli-like bacteria from hospital patients.Upon sequencing the genome,you discover that this bacteria has a group of about 30 genes,absent
THE ANSWER OF QUESTION 1：Group I introns require a G nucleotide or nucleoside, which are around in the original experiment. Modify the original experiment by isolating the RNA away from the rNTPs and determine whether splicing continues to occur. If splicing still occurs, the mechanism is probably similar to Group II, if splicing no longer occurs, it could be similar to Group I.
THE ANSWER OF QUESTION 2:The two splicing mechanisms have distinctly different intermediates, which can be distinguished on a gel (eg have radiolabeled rUTP in original transcription reaction so that mRNA is visible by autoradiography). Group I intermediates are linear, whereas Group II intermediates contain a lariat structure which will run differently on a gel as compared to a linear piece of mRNA of the same length.
这是MIT开放课程上的一道题 hope you enjoy!