Circle the Following E.coli genotypes that will metabolize lactose if lactose is present in the culture
a) I^+ P^ – O ^+ Z^ + Y^+ A^+
b) I^s P^+ O^+ Z^+ Y^+ A^+
c) I^– P^+ O^+ Z^+ Y^+ A^+
d) I^s P^+ O^c Z^+ Y^– A^+
e) I^+ P^+O^c Z^– Y^+ A^+
The genotype C will metabolize lactose if present in medium.
Explanation: Here repressor protein is absent. Therefore lac operon is always on, metabolizing lactose if present.
Why other options are wrong
a) A defective promoter region (P^ -). Therefore, RNA polymerase cannot transcribe the lac operon.
b) Is codes for a repressor that cannot bind to inducer. Therefore lac operon is off even in the presence of lactose
d)A defective repressor & defective lactose permease (Y^-). Therefore lac operon is off even in the presence of lactose
e) A defective beta galactosidase (Z^-). Even if lactose induces the operon, lactose cannot be metabolized in the absence of beta galactosidase.
Circle the Following E.coli genotypes that will metabolize lactose if lactose is present in the culture...