he Lac Repressor protein, which we will talk about a bit later in the course, is important for controlling expression of a number of genes in E. coli. There are about 10 copies of the repressor per cell. What is the intracellular molar concentration of the repressor molecules? Give your answer in nanomolar (nM) rounded to the second decimal place. The following facts should help you reach the correct answer: For this purpose assume an E. coli cell is a cylinder whose diameter is 1 µm and its length is 2 µm. Volume of a cylinder is [length x area of cross section] ? = 3.14 1 mL = 1 cm 3 Avogadro's number = 6 x 10 23 1 nM = 10 -9 M