Please notice the answer requirements below the question ables Charts Smart Art
ID: 167192 • Letter: P
Question
Please notice the answer requirements below the question ables Charts Smart Art Review Paragraph Styles AaBbccDdE AaB No spacing Heading 1 Heading 2 Normal J 2. (3 pts If you wanted to engineer self-splicing DNA, would you try to make a group I or group II self splicing intron? Explain your reasoning. Grading: 1 pt for correctly indicating which type of self splicing intron would be more likely to be found in DNA. pt for explaining why the one you picked could work better with DNA, 1pt for explaining how you eliminated the otheri in both cases with clear reference to the mechanisms of splicing
Explanation / Answer
Out of Group I and Group II,Group II introns are preferred
because Group II introns are mobile genetic elements that are found in bacterial and organellar genomes and are thought to be ancestors of spliceosomal introns and retrotransposons in eukaryotes. They consist of a catalytically active intron RNA (“ribozyme”) and an intron-encoded protein (IEP), whose combined activities enable intron proliferation within genomes. The group II intron RNA catalyzes its own splicing via transesterification reactions that are the same as those of spliceosomal introns, yielding spliced exons and an excised intron lariat RNA. The IEP is a multifunctional reverse transcriptase (RT), which is related to non-LTR-retrotransposon RTs and assists splicing by stabilizing the catalytically active RNA structure. It then remains bound to the excised intron RNA in an RNP that invades DNA sites. DNA invasion occurs by a remarkable mechanism in which the intron RNA uses its ribozyme activity to reverse splice directly into a DNA strand, after which it is reverse transcribed back into DNA by the IEP. Cycles of RNA splicing and reverse splicing enable the introns to proliferate to new DNA sites, while minimally impairing gene expression.
The characteristics of group II introns, including their splicing and mobility mechanisms, active-site structure, and naturally occurring variants that are split into two or more functionally reassociating segments, suggest an evolutionary scenario for the origin of introns, the spliceosome, and retrotransposons in eukaryotes. An evolutionary relationship between group II and spliceosomal introns appears increasingly plausible in light of newly obtained structural information, and indeed, a recent hypothesis asserts that group II intron invasion was the major driving force for the emergence of eukaryotes. Group II introns have also found practical applications as novel gene targeting vectors (“targetrons”), whose ribozyme-based DNA-integration mechanism enables their ready reprogramming to insert into desired DNA sites with high efficiency and specificity.
Group I introns encode site-specific DNA endonucleases that function in intron mobility and in some cases have adapted to function in RNA splicing,The group I intron endonucleases promote the site-specific insertion of the intron at the identical location in an intronless allele, a process referred to as homing.In addition to homing, phylogenetic evidence indicates that group I introns transpose to ectopic sites and undergo horizontal transmission between organisms.Group I introns encode different types of DNA endonucleases.