A scientist is studying a gene (grn) carried by a bacteriophage that allows a host bacterium to produce a green metabolic product before lysis. The scientist has four bacteriophage mutants for this gene. Mutant 1 has a nonrevertible mutation in grn while Mutants 2, 3, and 4 each have a revertible mutation in grn. After plating pairs of mutants and subsequent coinfection of host cells, the scientist observed the following:
| I. | Mutants 1 and 2: no green product |
| II. | Mutants 1 and 3: very rare green product |
| III. | Mutants 1 and 4: rare green product |
Which of the following is NOT consistent with these observations?
◦ A partial deletion in Mutant 1 overlaps a base-pair substitution in Mutant 2.
◦ Mutant 2 has a base-pair substitution at a different site than Mutant 3.
◦ Mutant 3 has a base-pair substitution at a different site than Mutant 4.
◦ Mutant 1's deletion is closer to the base-pair substitution in Mutant 3 than it is to the base-pair substitution in Mutant 4.
◦ A green product should be observed if coinfection occurs with mutants 3 and 4.
Single-gene inheritance tracked at the DNA level
Mutant sites in the PKU gene
The exponential amplification of the gene in PCR.
Relationship between the number of CAG repeats in a gene and the age of onset of Huntington disease.
A gene map for chromosome 12 from the NCBI database Map Viewer
Effects of Ac and Ds elements on gene expression