desire definition - Chromosomal vs genomic DNA (Feb/22/2007 )
Is there someone out there who can give me a clear distinct definiton between genomic and chromosomal DNA?
no because they are the same thing... well, genomic DNA can be found in chromosomes (interacting with histones, nucleosomes etc) or you can have purified genomic DNA that is not in the chromosomal form.... so all chromosomal DNA is genomic DNA but not all genomic DNA is necessarily in chromosomal form...
Sorry, not too much clear and distinct, but maybe someone else can do better....
Squirrelgirl: Beccaf explain well, but you still confuse then you need to understand first what is the genome and the chromosome. Here is some definitions:
1.genome= Total genetic information carried by a cell or organism.
2.genomic DNA= All the DNA sequences composing the genome of a cell or organism.
3.chromosome= In eukaryotes, the structural unit of the genetic material consisting of a single, linear double-stranded DNA molecule and associated proteins. During mitosis, chromosomes condense into compact structures visible in the light microscope. In prokaryotes, a single, circular double-stranded DNA molecule constitutes the bulk of the genetic material.
I understand it in this way:
The complete DNA sequences in the cell: the set of nuclear DNA plus DNA from the organelles like mitochondrial or chloroplast, etc., if it's the case.
Only the DNA of the set of chromosomes. Not mitochondrial, plasmid, etc.
Although, sometimes, when people say “genomic DNA” they really mean chromosomal DNA.
Please, if I'm wrong, correct me!
It's funny, but sometimes we talk about something everyday, then we realize we don't really have the concept clear enough, don't we??!!!!!
I think genomic DNA is only nuclear DNA, true you have the mitochondrial genome and that is mitochondrial genomic DNA but it is not grouped in with nuclear DNA when you say genomic DNA you are usually just meaning nuclear genomic DNA unless otherwise stated...
I think the term genomic DNA was introduced after the discovery of reverse transcription. gDNA is named like this to avoid confusion between DNA, cDNA etc.
It would be more appropriate to speak of chromosomal DNA or nuclear DNA when you mean only the DNA stored in the chromosomes. Mitochondrial DNA is sometimes refered to as mtDNA.
However, if you use a standard DNA purification from whole cells than you have a mixture of chromosomal DNA and mtDNA and in most cases, this is reffered to as genomic DNA.
terminology ... never start thinking about the "true" meaning of a word - it's all a question of definition...