Suppose That You Generate CDNA Libraries for the Same Cell

Multiple Choice

Suppose that you generate cDNA libraries for the same cell line under different conditions. Also suppose that when you compare the libraries, you find that some cDNAs in one library are missing from the other library. What is the best explanation for this result?

A) One of the cDNA libraries is really a genomic library.
B) There was an error in generating one of the cDNA libraries, and some of the sequences were not cloned properly.
C) Even the same cell type will change gene expression as conditions change. The difference in cDNAs tells which genes are expressed in each set of conditions.
D) The probe used in the Southern blot of the libraries must have been poorly constructed.