Table 11-1: Synthesis of β-Galactosidase and Permease in Haploid and Heterozygous Diploid Operator Mutants

 

 

β-Galactosidase (Z)

Permease (Y)

 

Strain

Genotype

Noninduced

Induced

Noninduced

Induced

Conclusion

1

O+ Z+ Y+

−

+

−

+

Wild type is inducible

2

O+ Z+ Y+/F′ O+ Z− Y+

−

+

−

+

Z+ is dominant to Z−

3

OC Z+ Y+

+

+

+

+

OC is constitutive

4

O+ Z− Y+/F′ OC Z+ Y−

+

+

−

+

Operator is cis-acting

Note: Bacteria were grown in glycerol (no glucose present) with and without the inducer IPTG. The presence or absence of enzyme is indicated by + or −, respectively. All strains are l+.