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Grade 12th PassZoology

Genomic DNA is digested with Alu I, a restriction enzyme which is a four base -
pair cutter. What is the frequency with which it will cut the DNA assuming a
random distribution of bases in the genome :
[A] 1/4
[B] 1/24
[C] 1/256
[D] 1/1296

Profile image of ASh
8 Years agoGrade 12th Pass
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1 Answer

Profile image of Arun
8 Years ago
Alu I has the cut site 5' AGCT 3'
                                 3' TCGA 5'

so it is evident that wherever there will be the above sequence in the DNA fragment Alu I will make blunt cuts over there.
Now according to the question, if there is random distribution of bases in the genome, the probability of occurrence of the above cut sides will be
1/(4^4) = 1/256 [since AluI is a 4 cutter R/E]

 So the frequency will be 1/256.
 
Regards
Arun (AskIITians Forum Expert)