bacteriophage You have a new mutagen that always creates 2 bp insertions or dele
ID: 165819 • Letter: B
Question
bacteriophage You have a new mutagen that always creates 2 bp insertions or deletions. You use this mutagen to recover many new mutations in the bacteriophage rllA gene. Describe a 2-step procedure to isolate the mutations, so as to be as confident as possible that they are truly mutant for rll function. Answer in ONE SENTENCE only! Such as "First [do xxx], then [do yyy]". ______________________ Describe a 2-step procedure so that you would know that they are all mutant for rllA and not for rllB. Answer in TWO SENTENCES maximum! ___________________________Explanation / Answer
(A) to know the mutation is in rII locus first we will plate the host(E. coli K strain) on agar plates and then infect the plates with rII mutants and rII wild types. the wild type will lyse the bacteria whereas, mutants will not. When tested on E. coli B wild type will produce smaller plaque as compared to mutants which cause rapid lysis.
(b) If A(rIIA) is mutated it will not complement mutant A on same gene whereas, will complement mutant B(rIIB) on different gene this unit is called cistron. if the mutation is present in A then the B on other gene will complement it and produce wild phenotype which can lyse K strain(E. coli) but if both A& B are mutated then, no wild phenotype will be obtained(no lysis of K strain). thus, this way we can find rIIA mutants.
p.s. wild type can lyse K strain and mutants can't while both wild and mutants can kill B strain.
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