Guess this is not an answer but that’s all I know 🙁
cDNA(complementary DNA) is made from mRNA and cDNA libraries consist of only coding regions(no introns) so they are smaller than genomic libraries(include whole genome).

This isn’t the answer but some more qs-

Why the ”smaller” matters here? because these are too small things…
Thus the storage prob. can’t be the the advantage of cDna lib.s over Gnomic ones… i wonder if its easier to introduce a smaller DNA into the bacteria or the orgaism using a an advantagious vector. Why? smaller size of molecule will have greater momentum at givn energy, so rate of reaction will be higher.But i think both reactions will get completed within just a diff. of seconds.
Or is it just easy to get cDna that the gDna ]genomic DNA , my term[But i think its hard to get mRNA as it degrades quite quikly…

hrushikesh

Zami’s answer is correct. cDNA is made using reverse transcriptase from mRNA.
It is smaller than gDNA (which is not only 2810712 term ;)) because of its origin. indeed mRNA is maller than the whole genome. What is interesting is that in the case of eucaryotes it gives you the gene without the introns and it’s easier to clone in bacteria in the first step of the study. Later on you can (and will) come back to the complete form for a more complete analysis but it gives a good start.
And 2810712. You are looking for complicated things where there is none.

Substraction Cloning is a technique that utilizes cDNA

Not always, substractive hybridization can be performed without RT PCR in bacteria (it’s much easier. Any way it is one among many techniques that can be performed with cDNA. DNA microchip use a RT step for example.