Help me guyz i m new in the bioinformatics field

[sara sabir]

i need to know the relationship between the % of the nitrogenous bases of the diffracted dna of human, sheep and hen

[blcr11]

?Why would you expect there to be such a relationship? The fiber diffraction pattern of DNA depends mostly on salt conditions and relative humidity. It isn't (at least so far as I know) dependent on the base composition.

[sara sabir]

i wanted to say dat
as we noe dat the % of adenine is almost equal to thymin n cytosine is equal to dat of guanin
so is there any such other comparison wen v c da table of the % of nitrogenous bases of human sheep n hen etc

[sara sabir]

A G T C
human 30.9 19.9 29.4 19.8

sheep 29.3 21.4 28.3 21.0

hen 28.8 20.5 29.2 21.5


now from these values of nitrogenouses bases i need the relationships between them

[blcr11]

It’s still not clear to me what kind of relationship you expect, and none of this has anything much to do with “diffraction” no matter what you’re looking for. About all you can tell from these data is the relative %G+C content of the various DNAs; Human (39.7) < Sheep or Chicken which both have about the same (42.4 for Sheep, 42.5 for Chicken). I think base composition is a crude way to look at phylogenetic relationships (if that's what you're trying to do). You have to at least look at Cot curves or, better yet, sequence data.

[sara sabir]

i just wanna know the relationship of the values of these nitrogenous bases in different organisms

have u understood now?????

[blcr11]

No. As worded, your question is pointless.

I think you are trying to say something about the phylogentic relationships between species, but I don't believe you can say much about that with % base composition. If it isn't phylogeny you are looking at (as in genetic trees, and genetic relatedness etc) then I do not understand what you mean by "relationship of the values of these nitrogenous bases in different organisms". Maybe we have a language problem between us, I don't know, but I can't help you any more than this unless you re-phrase the question in a way that makes more sense.

[sara sabir]

first tell me dat
do u agree wid me wen i say dat the amount of adenine n thymine is almost equal to dat of thymine
n da amount of cytosine z equal to guanine in evry org ????

[blcr11]

Yes. That's Chargaff's Rule. The amount of A = the amount of T and the amount of G = the amount of C. This, we now know, comes from the base pairing requirements of dsDNA. Within experimental error, this will be true for DNA from all species. It is true for the DNA samples you listed. You said you already knew about A=T and C=G.

[sara sabir]

wat other such relation can v find among da bases

[blcr11]

There isn't any other.

[canalon]

There isn't any other.

The G+C content is sometimes used (at least in bacteria) as a wide but nevertheles interesting marker of exogenous genes.

MODERATOR NOTE: I want to remind everyone, and sara sabir in particular, that this is an internet message board, not an instant message service. You can take your time to write and spellcheck your posts to conform to the generally accepted form of english that everyone is familiar with, i.e. "da" is spelled "THE", dat is "that" etc. Thanks for all the forum mebers whose native language is not english slang...