DNA = Chromosome

[ssas]

Thanks guys.
What you have discussed here is very useful and insightful.
I have a clear answer now.

[wbla3335]

Perhaps I should just leave well enough alone, since I think the discussion up to this point at least clarifies the original poster's concern, but I've been ruminating about Canalon's comments. At first I agreed, but then I kept coming across situations in the literature that led me to doubt that this view is commonly held. Before the days of biochemistry, the chemist's definition of a molecule was something similar to: a collection of atoms covalently bonded to one another. But biochemists have changed (bastardised?) things a bit. Most biochemists consider hemoglobin, for example, to be one molecule, even though it consists of four polypeptides that are not covalently bonded to one another. Most also say that a DNA molecule is a double helix, even though the two strands are not covalently bonded to one another. I've had a quick look around for some officially accepted definition of a molecule, and I can't find one, certainly not a universally accepted one. So I think the answer to ssas's question depends on whether or not you insist on covalent bonding of all atoms as being integral to what defines a molecule. The majority of chemists would probably say yes, but the majority of biochemists would probably say no. So, a chromosome may, or may not, be a single molecule. Sorry ssas. (I hope I haven't opened a bottomless can of worms.)

[dfremed]

is this for a rutgers recitation quiz?

[klk218]

i read the discussion....and i was thinking that there are 2 dna molecules in a eukaryotic linear chromosome....someone said that there were 92 dna molecules, but that is totally off right? even if you considered the base pairs: arent there 22 base pairs for a total of 44 and then 2 sex chromosomes.....we wouldnt count the sex chroms right? i am going to go with 2 dna molecules...does that sound right



also where can i find out the number of base pairs for fruit flies and the likes...any website suggestions

[klk218]

ok so there are def 23 base pairs---i am an idiot....but is he asking about the base pairs of nucleotides or just chromosomes


The Human Genome Project is a massive undertaking, spearheaded by the Department of Energy and the National Institutes of Health, which requires "mapping" the location of some 100,000 genes along the 23 pairs of human chromosomes, then "sequencing," or determining the order of the three billion base pairs of nucleotides that make up these chromosomes.

from this website

http://www.lbl.gov/Science-Articles/Res ... alth3.html

[Navin]

I define a DNA molecule as a double stranded molecule. Hence I would say that there are 46 DNA molecules in a human cell.

[futulam]

there would be 46 chromosome because 23 chromosome come from maternal (mother chromosome) and 23 come from paternal (father chromosome) total to 46 chromosome.

[G-Do]

If the question is "how many molecules of DNA are in the nucleus?" you are on the right track.

However, if the question is "how many molecules of DNA are in the cell?" the correct answer is "I don't know" because there is a variable number of mitochondria in each cell, and each mitochondrion has its own DNA genome.

[sharan]

I find the interpretation of 23 "chromosomes"/ 46 DNA's/ 92 molecules in the human cell misleading and illogical. Its acceptance is seriously affecting the progress of science in other disciplines such as medicine. The number of "somes" in each human cell is 24. 22 pairs of autonomes + X chromo.+Y chromo.= 24 ! If female it is 22+X+X=24.
This number of somes is equal to the number of: vertebrae in the spine, bioelectrical circuits shown in the iris, foramen in the skull, moods/hours in the day, Chi Chi's in a year and probably many more items in nature which relate to our consciousness and the motions of Earth.
Bioelectronics explains that our 4 centres the hara, the heart, the brain and the spine/unison are connected by 24 circuits that link into an organ so that at any moment we have a emotion, a feeling, a thought and an experience in those respective centres. Since there are 4 nitrogenous bases in the changing part of DNA (directed inwards) which make up the somes it is likely that the ancient Tibetan system of 4 centres and 24 circuits creating 96 spaces is correct.

[jwalin]

basically a chromatin is equal to a DNA. that will help you even later

[JackBean]

is it? I thougth, that chromatin is DNA + all the binding proteins (or only histones?)

[jwalin]

sorry
is nearly equal to


i had put that so it would make the understanding easier