Lederberg and Tatum used the bacterial strains bio- met- leu+ thr+ thi+ and bio+ met+ leu- thr- thi- in their
experiments to determine if genetic recombination occurs in bacteria. Would it have been better to use two strains with the
genotypes met- leu+ and met+ leu- instead?
a. Yes, because it is easier to study 2 genes than 5 genes.
b. Yes, because the met- leu+ and met+ leu- strains only have one mutation, which makes it easier for genetic
recombination to occur.
c. No, because the met- leu+ and met+ leu- strains only have one mutation. A single random mutation could
restore methionine or leucine synthesis in the strains.
d. No, because strains with only one nutrient-deficient gene can still grow on minimal medium.
e. No, because cells have two genes that encode different versions of leucine, so the met+ leu- strain would still
be able to grow on minimal medium.
ANSWER: c
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