Final answer:
The true statement about "Polarity" in the context of bacterial gene expression is that c) it is when termination in a coding region located near the 5-end of a polycistronic mRNA causes the loss of both transcriptional and translational expression of all genes that follow it.
Step-by-step explanation:
In terms of bacterial gene expression, the statement that is TRUE regarding "Polarity" is option C: It is when termination in a coding region located near the 5-end of a polycistronic mRNA causes the loss of both transcriptional and translational expression of all genes that follow it. Polarity in this context refers to a transcriptional termination event that disrupts downstream gene expression within the same mRNA transcript. When such an early termination occurs, it can prevent the expression of subsequent genes in the operon, regardless of their potential function or importance.
In contrast, statement A is not necessarily true as all coding regions forming a polycistronic mRNA might not have the same orientation, and B is incorrect since ribosome traffic does not per se cause polarity. Moreover, statement D is also incorrect as a rho-dependent terminator located in the coding region of the last gene in a polycistronic mRNA does not illustrate the principle of polarity but merely signifies the end of transcription of that polycistronic mRNA without necessarily impacting the genes upstream.