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

Levels of expression vs presence.

Try to know in terms of its respective conceptions, my friend. Genomic DNA is the full set of DNA sequences from human chromosome, and cDNA sequence is expressed in a spatial and temporial manner which means the present state of gene expression.

Comparing the cDNA of a gene to the gene's genomic DNA allows one to identify exons and introns.

...and alternate splicing sites for alternate exons (but you should also get some of that from the mRNA populations). As an extreme example, the transcriptional co-repressor, CtBP, has an alternate first exon buried within the first intron, that codes for a huge structural domain in a totally different protein, RIBEYE, involved in vesicle trafficking in the retina, ear and pineal glands. Why? How? Go figure....

If you're into regulation, the intronic DNA seems to have a role, which is something you can't get from mRNA.