Jacob and colleagues developed a time-of-entry mapping technique. They used the genes for threonine and leucine synthesis (
thr and
leu), which are near the
oriT site, as selected markers. Additionally, they used an
E. coli F- strain P678 that has dysfunctional variants for all of the genes studied. They also used an HfrH strain that carried a functional allele for all genes studied. Which of the following statements is FALSE regarding the time-of-entry profile they acquired?

◦ Had the experiment continued, a time of entry map could be viewed for the entire
E. coli chromosome.
◦ The
azi gene is closer to the
thr and
leu genes than the
ton,
lac, and
gal genes.
◦ The
ton gene is found between the
azi and
lac genes.
◦ The
lac+ allele appears at about 16 or 17 minutes.
◦ At 40 minutes, nearly 20% of exconjugants screened for the selected markers have the
gal+ allele.