Percentage of recombinants Recipient Donor Тз 168PT 12.7 ТЗ T11 11.8 Тз T8 43.5 ТЗ Н25 28.6 168 Н25 44.9 TII Н25 41.4 TI Н25 31.3 T8 Н25 67.4 Н25 ТЗ 19.0 Н25 TII 26.3 Н25 TI 13.4 Н25 T8 45.0
C. Anagnostopoulos and I. P. Crawford isolated and studied a series of mutations that affected several steps in the biosynthetic pathway leading to tryptophan in the bacterium Bacillus subtilis . Seven of the strains that they used in their study are listed here, along with the mutation found in each strain.
Strain Mutation
T3 T−
168 I−
168PT I−
TI I−
TII I−
T8 A−
H25 H−
To map the genes for tryptophan synthesis, they carried out a series of transformation experiments on strains having different mutations and determined the percentage of recombinants among the transformed bacteria. Their results were as follows:(refer picture)
On the basis of these two-point crosses, determine the order of the genes and the distances between them. Where more than one cross was completed for a pair of genes, average the recombination rates from the different crosses. Draw a map of the genes on the chromosome.
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