Question

How does lactose get into an E. coli cell if the lac operon is turned "off" and the cell is not synthesizing lactose permease?

Answer 1

E. coli utilizes glucose as source of energy in absence of glucose E. coli uses lactose.

Explanation:

Lactose does not easily diffuse across the E. coli cell membrane and must be actively transported into the cell by enzyme permease
the enzymes galctosidase, permease and transacetylase are produced in small amount in absence of lactose.
when glucose is utilized and lactose is added synthesis of all the three enzymes increases about thousandfold with in 2 to 3 times.
so with small amount of permease present in cell lactose is diffused across membrane.