$\text{Statement for Linked Answer Questions 52 and 53:}$
An E $coli$ cell of volume $10^{-12}$ $cm^3$ contains 60 molecules of lac-repressor. The repressor has a binding affinity (${K_d}$) of $10^{-8}$ M and $10^{-9}$ M with and without lactose respectively, in the medium
Therefore the lac-operon is
- repressed and can only be induced with lactose
- repressed and cannot be induced with lactose
- not repressed
- expressed only when glucose and lactose are present