Internet0 min ago
Cells
What does the D stand for in DNA?
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For more on marking an answer as the "Best Answer", please visit our FAQ.Deoxy is prefix used in forming names of chemical compounds, and in simple terms, denotes the absence of oxygen from a certain position in a molecule. This is the meaning in DNA.
Deoxy is also used in the naming of chemical compounds to denote a compound containing one less atom of oxygen than the reference substance.
This was never the intention when the molecule was named. In effect, the "ribo" is silent as far as the DNA acronym goes.
In comparison to the molecule RNA (ribonucleic acid) DNA lacks the OH group at position 2 of the sugar. Deoxy on its own is meaningless. It is an adjective describing the ribose sugar and as such needs to be linked to the ribose
It is a less popular misconception that the D only stands for Deoxy and that the ribose is silent.
R = Ribo (ribose)
D = Deoxyribo (deoxyribose)
As a result, whenever the prefix is used in the title of an unknown chemical compound, a chemist/biochemist is provided with a feature of the compond to follow.
As a result, the term is not meaningless even when used in isolation. I would also point out that the term "adjective" is a word that is both innapropriate, incorrect and not used in science.
I acknowledge your basic comparison of DNA and RNA which will suffice here. However, the polynucleotide was not prefixed Deoxy to convey the lack of an OH group at position two of the molecule.
For more detailed information on precisely how the nucleic acids were named, I would ask that refer to one of the many works detailing the discoveries of Watson and Crick et al. It may then be seen that the "D" was does indeed stand for Deoxy.
Your confusion on this point is understandable and I would add that over the years, many laymen have told me that they considered the "D" to stand for Deoxyribo in this polynucleotide. Nevertheless, my university department has conveyed the true meaning of the term to our students since 1954. Furthermore, I remain uncertain from your last posting if you consider DNA itself to be a mere ribose sugar, which it is far from not.
As a university department, we are aware of continuing ill-researched assertions as to the meaning of the "D" that continue to be prevalent on the internet. Hardly a day goes by without my staff being approached on the issue and I thank you for the opportunity to clarify the issue..
Note for the prof?
Whilst still not agreeing with your replies I do not intend to continue the arguement. I am quite happy that I am correct, however, there is a life to be lived rather than getting involved in such pettiness.
One word of advice: Don't assume that just because someone disagrees with you that they are a 'layman'. In this case, you are so very, very wrong.
With all due respect, I think you may have misread my postings. At no point have I stated that DNA is an acronym for anything other than Deoxyribonucleic acid. My point was that the "r" of the "ribo" is silent (ie not used) as far as the acronym is concerned.
In this respect, DNA is no different to many other complex organic compounds in which the initial letter of some of the radicals in the molecule are omiited to prevent the acronym from being excessively long. There is little point in assigning an acronym to a compound that is almost as difficult to recall as the full IUPAC name itself.
dynamicduo:
I have noted your comments and you are entitled to your opinion in this complex area of biochemistry which can be challenging to undergraduates and my learned colleagues alike - no doubt you are capable of the same.
Your generalised remark, that you do not agree with my replies puzzles me. Are you implying that my postings in toto are incorrect? If you wish to challenge my statements, kindly be more specific.
Disagreements are endemic throughout the scientific community and occur on a daily basis throughout academia and in the learned journals. As you are implying that you are not a layman, you should be aware of this. It follows that I therefore cannot afford to assume that a dissenter is unquestionably a layman -disagreements occur no matter how high up the academic ladder we are. For this reason I do not assume that someone who disagrees with me is a layman and you will note that I did not imply that you were a layman in the penultimate paragraph of my last posting despite the fact that you seem to consider that I did. I would suggest that you read the paragraph concerned again.
As explanation for some of the wording in my previous post, I have seen the term deoxynucleic acid in print; is there actually such a thing? Of course, if there is, it should never be equated with DNA.
I appreciate your confirmation and comments.
Thank you for your continuing interest.
Yes, you are correct that DNA does stand for Deoxyribonucleic acid and you can regard �deoxyribonucleic� as a compound word as stated. DNA is an organic molecule and there are rules devised by IUPAC and others on the naming of such compounds.
Basically, what happens is that the structural formula of the compound is examined and broken down into radicals and elements and these are strung together in a set way to form the full chemical name. To take this one step further, when organic compounds share the same empirical formula with others, it becomes necessary to label the position of some of the radicals on the structure in order to discriminate between the compounds concerned. Earlier today, I used a chemical with the empirical formula C2H5OCL known as chloromethyl ether. Two other organic compounds with the names Ethyl hypochlorite and Ethylene chlorohydrine both share the above empirical formula with the chemical I used. However the structural formula of these three compounds is very different from each other which is why structural formulii are so important � the physical properties of the three chemicals mentioned resemble each other about as closely as chalk and cheese!.
(Continued)
Ribo is not the plural of ribose. What happens is that when an organic compound is named, the name of another component that is within it is often shortened to prevent the name becoming unwieldy. In this case, ribose is shortened to ribo. It can also make it easier to tag on the next word in this way � I think you will agree that if the word ribose was in the middle of the name of an unfamiliar compound, it could be difficult to know if one should pronounce the �e� on the end or not. This situation does not arise with an �o� in that position. As another example, when glucose is part of a molecule, its presence is invariably shortened to �gluco�
Finally, the D in DNA does indeed stand for deoxy despite the view of dynamicduo.
I can confirm that you have seen the words deoxynucleic acid in print. The original paper published in �Nature� in April 1953 by Watson and Crick was titled: �Molecular Structure of Nucleic Acids: A Structure for Deoxynucleic Acids.� Their paper discussed their proposal of the structure of what everyone knows now as The Double Helix.
DNA is a nucleic acid, which is very complex molecule (macromolecule) made from repeating nucleotides. Incidentally, DNA is one of only two nucleic acids, the other being called RNA.
You can regard �Deoxynucleic acid� as an alternative or old name for what we now call Deoxyribonucleic Acid - the name may be seen most often in textbooks and papers published in the 1950s and 1960s. It is no longer in common use and tends to be discouraged.
You may also have seen reference to �Deoxyribonucleic acids�. This is usually a reference to the fact that the chemical make-up of DNA differs from species to species. This is immensely useful nowadays in fields such as forensic pathology where it is possible to quickly establish whether blood, for example, is of human or bovine origin � sometimes the sample is too small or contaminated for microscopical examination.
To end, please accept my apologies for being so long winded!!!
To summarise, it seems to me that if you look at this matter from a totally impartial point of view, the key point is that DNA was the acronym for deoxynucleic acid when Watson and Crick wrote their paper in 1953. This was the original name of the molecule.
The verify this, you need only to look for deoxynucleic acid on Google.
Breaking down the acronym into its component parts then shows that the D must have stood for Deoxy and nothing else.
This is an indisputable fact which may be seen from common sense alone without any scientific knowledge.
This is the reason why I suggested that dynamicduo should review the historical aspects of this matter.