instead of creating a point mutation, edit the base pairs around the cleavage si
ID: 148615 • Letter: I
Question
instead of creating a point mutation, edit the base pairs around the cleavage site. In order to achieve this, a new template strand of DNA must be supplied with homology regions exactly matching those surrounding the base pairs that are to be edited, with the mutations located in between the homology regions on the new template. For example, if the sequence to be edited (bolded) was ATTAXXXXGCTA, then the template strand would look like this: ATTAYYYYGCTA. What type of DNA repair is this system making use of? Would you expect the mechanism in above question to be 100% effective in eukaryotic organisms? Prokaryotic? Why or why not?
Explanation / Answer
Genome is not a static entity. It is dynamic in nature. A heritable change in genetic level in the genetic material of an Organism that gives rise to alternate forms of any gene is called mutation.
Mutations are generally recessive, but dominant mutations also occur. These are ultimate source of all genetic variation and it provides the raw material for evolution It results in the formation of alleles, without mutation all genes would exist in only one form, where they would be able to evolve and adapt to environmental changes. These are recurrent i. e the same mutation may occur again and again.
In the above question,the mutation is insertion mode where base pairs are inserted exactly homologous to the parental strand considered under non frame shift mechanism.
If we speak about effectiveness, it depends on factors like genome size, mutation rate, action of polymerases.
Considering these factors, viruses are much more effective in possessing high mutation rate because they contain RNA polymerases or reverse transcriptase enzyme. This enzymes have extremely high rate of error compared to standard DNA rates. Eukaryotes are said to posses low rate of fidelity in polymerase action.
So the order is viruses mutation rate>prokaryotes> Eukaryotes.
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