cDNA and genomic library

Simple differences include:

cDNA is complementary DNA it is the DNA complement to the mRNA isolated from a cell. So it is a library of the "active" part of the genome. The transcriptome.

Genomic DNA is the DNA found in the nucleus of prokaryotes and it is litterally the translation of the entire genome.

gDNA = is the complete DNA present in a cell, including intron, exons, junk DNA etc, as in human our gDNA would consist on all 3 billion nucleotides pairs.

cDNA = a cDNA library is produced by reverse-transcribing the cells mRNA, this would give you a library that consists on the DNA sequences of all the RNA that is transcribed from the gDNA, and excludes the introns

Hello, cDNA is synthesized from messenger RNA (mRNA). This means cDNA contains only the functional coding or protein coding regions!

In mature mRNA, the introns are spliced out of mRNA so only exons (protein coding regions are present).

When cDNA Libraries are constructed, not all clones are full length when they are oligo dT primed. The short clones mean several clones are often needed to complete the coding region at the 5' end. If it was a rare mRNA this may be difficult but if it was a common mRNA then one probing usually pulls out enough copies to complete the sequence. (There are also cDNA kits to prime specifically from the 5' as well as the 3' end so you are more assured of getting overlapping clones.) Clones are short and easy to sequence. You do not know where the introns are located so a genomic clone will be needed for that. A cDNA clone is needed to transfect cells for protein production or for cell based assays.

Genomic libraries will be very unlikely to contain an entire coding region on one clone due to the size of the introns. Several clones would then need to be analyzed for overlap between them. If the cDNA is used the intron donor and acceptor sites can be easily sequence from the known cDNA sequence. If there is no cDNA the entire sequence will have to be done. Introns can be very difficult to sequence if the contain palindromic repeats or long stretches of Alu repeats. Ideally the cDNA copy will be found first to ease & shorten the sequencing needed from the genomic clones. If distant regulation sequences like enhancers are of interest then the genomic clone is necessary.

DNA is made from messenger RNA (mRNA) so contains only the functional coding region. (The introns are spliced out of mRNA.) When the library is constructed not all clones are full length when they are oligo dT primed. The short clones mean several clones are often needed to complete the coding region at the 5' end. If it was a rare mRNA this may be difficult but if it was a common mRNA then one probing usually pulls out enough copies to complete the sequence. (There are also cDNA kits to prime specifically from the 5' as well as the 3' end so you are more assured of getting overlapping clones.) Clones are short and easy to sequence. You do not know where the introns are located so a genomic clone will be needed for that. A cDNA clone is needed to transfect cells for protein production or for cell based assays.

A genomic library will be very unlikely to contain an entire coding region on one clone due to the size of the introns. Several clones would then need to be analyzed for overlap between them. If the cDNA is used the intron donor and acceptor sites can be easily sequence from the known cDNA sequence. If there is no cDNA the entire sequence will have to be done. Introns can be very difficult to sequence if the contain palindromic repeats or long stretches of Alu repeats. Ideally the cDNA copy will be found first to ease & shorten the sequencing needed from the genomic clones. If distant regulation sequences like enhancers are of interest then the genomic clone is necessary.

Genomic libraries contain much more sequence information than cDNA libraries.
Genomic libraries contain coding and noncoding (regulatory, intron, etc..) sequences, whereas cDNA libraries contain only coding sequences (with associated 5' and 3' UTR regions).
A genomic library is prepared from total genomic DNA, whereas a cDNA library is prepared form mRNA that is converted into complementary DNA.

Ela, what answer would you choose as the most accurate?

I am not sure, which one would you choose? plz help i have to submit this question by tomorrow