genomic DNA and cDNA - question (Nov/10/2008 )

I am coming across literature articles that analyze genomic DNA lines and the cDNA lines. What are some of the reasons why the genomic DNA of a line and its cDNA are studied in scientific experiments? I know that a cDNA is synthesized from mRNA by reverse transcriptase. But I don't fully understand what can be gained from comparing a genomic DNA line to its cDNA line.

Please help

I'm not really sure, what you call lines, in here. Or what scientific experiments you meant.

But cDNA is reverse transcribed RNA, thus it represent the transcript of the genomic DNA.
There are several differences between transcript and genomic DNA, first, cDNA doesn't contain introns. cDNAs are much shorter, as introns can span thousands of pase pairs, and therefore easily cloned and worked with. Also there could be more than transcript of one genomic sequence (different introns are spliced out) so you can study one particular or see all of them. It is the transcript, that is translated to the protein, so you look axactly on the template of protein, you can detect splicing errors othervise not obvious from the genomic sequence.