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This article contains no reference to DNA isolation - how it works, techniques employed etc. An article on such a subject would be appreciated. Perhaps with a paragraph linking to it on this article. The Spith ( talk) 10:24, 10 October 2008 (UTC)
I just deleted that whole section; I thouhgt the whole gen eng thing was poorly written, and since the GE article has a great lead, I just copied it. re phenol - I'm sure people somewhere still use phenol chloroform, but it is pretty rare; most people nowadays buy isolation kits from companies like qiagen, invitrogen, Sigma, etc. (use of toxic reagents like phenol is frowned upon by safety officers, phenol is a pain in the but - you have to store it frozen or it oxidizes and turns all sorts of colors, it causes severe burns, etc) eg http://www.promega.com/tbs/tm330/tm330.pdf describes a proteinase K protocol , which should take the place of phenol, which is a deproteinization reagent. anyway, isn't there a prohibition against how to do it stuff in wiki ? Cinnamon colbert ( talk) 01:46, 27 October 2010 (UTC)
The second paragraph of the Properties section states that "In living organisms, DNA does not usually exist as a single molecule, but instead as a tightly-associated pair of molecules." Usually (e.g. in the referenced Biochemistry book) such pair is referenced as single double stranded DNA molecule. —Preceding unsigned comment added by Ignatich ( talk • contribs) 15:39, 16 October 2008 (UTC)
By the strict definition of a molecule used in many chemistry texts, one might consider each antiparallel chain of DNA to be an individual molecule since the complimentary strands are bound not by covalent bonds but by hydrogen bonds. This is so restrictive as to be unconventional at best and in the realm of biological sciences, unnecessarily confusing. For example, a broader definition of a molecule in the "Dictionary of Chemistry", by McGraw Hill does not restrict a molecule to having only covalent bonds. Although some texts restrict the term "molecule" to atoms covalently bonded some don't...eg., General Chemistry, Zumdah. I just reviewed a variety of cell bio and general bio texts: "The Cell", by Alberts et al, "Biology" by Arms and Camp, "Facts on File Dictionary of Biology", "Biology", Campbell and Reece; all which refer to the DNA MOLECULE being double stranded. By convention, the DNA molecule is considered as two antiparallel strands held together by hydrogen bonds. I am sure you have heard numerous times in labs when fellow scientists refer the the DNA molecule melting...(the basis of PCR). If the WIKI article on DNA wishes to split hairs and break from convention, based on the more restrictive definition of a molecule, it should clearly state the reason... otherwise it is very confusing. Also, the citation of the Watson and Crick seminal paper in this regard is peculiar since it does not address anywhere that the DNA exists in living organisms as separate molecules. The paper proposes "A" structure for the "salt of deoxyribose nucleic acid..." They describe what is now known as the 'B" form.
Medicuspetrus ( talk) 19:27, 12 August 2009 (UTC)
Just a note. The article states a that adenine...is a nucleotide. It is NOT...it is a nucleotide base.
Medicuspetrus (
talk) 13:31, 12 August 2009 (UTC)MedicusPetrus
I think what conveys the right idea is to talk about two strands that are nominally a single molecule by the standard of covalent bonds Cinnamon colbert ( talk) 01:39, 27 October 2010 (UTC)
Searching for 'sugar pucker' leads to this article, but then doesn't appear to be covered in the article. Is it possible to get a page or section for this topic? —Preceding unsigned comment added by 134.36.68.234 ( talk) 00:12, 20 October 2008 (UTC)
In the section Labeled Polymerases it states, "Consequently, all polymerases work in a 5′ to 3′ direction.[82]" this is an inaccurate quote for the source. Most DNA polymerases work in the 3' - 5' direction. This part should be edited so as not to confuse new biology students
Ezendl1 ( talk) 02:43, 11 November 2008 (UTC)ezendl1
To, Polymerases act by catalyzing the addition of a 5' monophosphate group to the 3' hydroxy group of the primer. This is referred to as 5' to 3' synthesis, since the growing chain grows toward the 3' direction Cinnamon colbert ( talk) —Preceding undated comment added 01:34, 27 October 2010 (UTC).
The article on symmetry says that DNA is an example of a non-repeating helical symmetry in which "the angle of rotation θ required to observe the symmetry is an irrational number such as radians that never repeats exactly no matter how many times the helix is rotated."
Now I understand, of course, that the pitch of real DNA will vary vastly according to the cellular environment, not just binding proteins but just salt concentrations, and at least a little according to the base pair composition, and that it will also vary moment to moment because of thermal fluctuations, so this is an absurd point, but even so...
Is there a physical force that should bring a hypothetical isolated strand of DNA at rest in the vacuum into one or more n-fold helical symmetries, rather than a non-repeating symmetry?
For example, some sort of resonance stabilization that allows transmission of vibrational modes along the helix, or interactions between virtual emissions in the radio spectrum along the axis...? Wnt ( talk) 20:06, 23 January 2009 (UTC)
I had a look at PMID 10884351, the question of whether or not B-DNA has a symmetry axis running the length of the helix seems much more complicated than you'd reasonably expect. The answer appears to be "sometimes" but perhaps only with palindromic sequences. Tim Vickers ( talk) 20:30, 23 January 2009 (UTC)
RNA and DNA are similar structures. DNA is a single stranded molecule while RNA is double stranded. They are in no other ways different —Preceding unsigned comment added by 71.120.67.202 ( talk) 21:36, 2 February 2009 (UTC)
Could somebody please take out the " Large version" link. It is unnecessarily self-referential annoying since it has been translated into other articles on DNA in other languages (and the reference saying "Created from PDB 1D65" should also be deleted because it is also useless.) 98.166.139.216 ( talk) 22:57, 20 February 2009 (UTC)
I find the history section is lacking. The story stops around 1960. What happened after? 222.64.113.175 ( talk) 03:34, 10 April 2009 (UTC)
I just read a minireview from 1997, estimating the number of oxidative lesions in the DNA (per human cell) to about 1,5x 105 and not 500 as it says here. If you want a update the review is by Beckman and Ames; Oxidative decay of DNA, J biol chemistry, 1997. Sniffe35 ( talk) 07:55, 26 April 2009 (UTC)
RE: ``DNA reference "Hi there, I'm afraid Google searches aren't good references as the results can change over time. If there was something in the DNA article that you think needs more references I'd be happy to try to find something else. All the best" Tim Vickers ( talk) 15:47, 3 May 2009 (UTC)
Hello, Tim. I 'm also afraid that the current DNA article version has a basic flaw in the over-simplified presentation of A-DNA structure and B-DNA configurations in regards to the interpretation of the corresponding X-ray patterns. This could have been corrected by adding relevant references of published papers that however is being prevented by the over-protection of this entry through locking up the editing. At the very least a new section could be added up that allows the correction of this basic flaw which places in doubt the scientific value of ``comparisons" between A-DNA and what is commonly still called the `B-DNA' configuration set. Furthermore, there are several factual errors also about the conditions under which A-DNA X-ray diffraction patterns have been generated, not to mention the lack of adequate credit to the experimenters involved. For an improved entry such comments with the introduction of the appropriate literature references should help. Cheers. Bci2 ( talk) 10:27, 4 May 2009 (UTC).
Currently there is a line that says that the analysis of the x-ray diffraction data "requires a different approach from that of the standard analysis by Fourier transforms of Bessel functions". Even before I started moving things around it was not clear to me what the alternate methodology is. Have i missunderstood or was it never mentioned?
Then of course we have the issue of whether this article should be getting into the mathematical methods of interpreting the x-ray data. Should we be a little more general and just give the gist of what the spots mean i.e. something about determining the pitch, base repeat distance? David D. (Talk) 05:31, 5 May 2009 (UTC)
OK, I've made a whole bunch of changes to try and make it more understandable from my perspective. Is the point about the B-DNA x-ray diffraction data that it is harder to get an accurate structure or that different methodology is required to determine an accurate structure? I now think the former, from reading the references, so please check that what I have written in the text and figure legend makes sense. David D. (Talk) 06:15, 5 May 2009 (UTC)
Bci2, I'm confused, your edit here seems to contradict what you say above. i thought the whole point here is that the A and Z form do not require modeling too? David D. (Talk) 15:06, 5 May 2009 (UTC)
"In 1953 James D. Watson and Francis Crick suggested what is now accepted as the first correct double-helix model of DNA structure in the journal Nature[6]. Their double-helix, molecular model of DNA was then based on a single X-ray diffraction image (labeled as "Photo 51")[135] taken by Rosalind Franklin and Raymond Gosling in May 1952, as well as the information that the DNA bases were paired--also obtained through private communications from Erwin Chargaff[136][137][138][139][140][141] in the previous years. According to James Watson, after they had figured out the structure of DNA on February 28, 1953, he and Francis Crick walked into the Eagle pub in Cambridge, England and Crick announced.. "We have found the secret of Life." [142]"
Unfortunately the above paragraph perpetuates the apparent myth of 'We have found the secret of life' and to make matters worse puts the apparent quotation into bold, which needs to be reverted.
There is in fact NO reliable record of Francis Crick having said this; in Francis Crick's 1988 autobiography, he said of this event: "According to Jim, I went into the Eagle, the pub accross the road where we lunched every day, and told everyone that we'd discovered the secret of life. Of that, I've no recollection, but I do recall going home and telling Odile that we seemed to have made a big discovery." (Page 77, "What Mad Pursuit", Chapter 6, "How to live with a Golden Helix".)
However James Watson said (quote) "Francis winged into The Eagle to tell everyone within hearing distance that we had found the secret of life." (Page 111, Chapter 26, "The Double Helix)".
Why does this quotation from James Watson need to be taken with the proverbial 'pinch of salt'? The fact that the person said to have made the statement could not remember having said it! In his "book genes, girls, and gamow", James Watson states (quote): "During my absence, the first newspaper article that reflected an interview with Francis Crick came out. It was in the Sunday Telegraph and reached a large audience." (from page 21, Chapter 4: Cambridge July-August 1953.)
The only problem being that the Sunday Telegraph did NOT exist in 1953, and repeated searches of the newspaper archives have NOT found any trace of such an article, with a Crick interview!
So Watson may not be an entirely reliable source for this quotation, even when repeated by the BBC; I suggest that the text and the BBC reference need to be qualified to reflect the above?
91.110.218.146 ( talk) 12:13, 10 May 2009 (UTC) Martin Packer
Thanks Tim, I don't doubt that something was 'said' that Saturday afternoon in The Eagle - but I suspect that Watson was referring to Crick's booming voice inadvertently broadcasting the good news of the discovery rather than him making a specific announcement to all and sundry within hearing distance. (Their lunch incidentally was either the shepherd's pie or sausage & beans!) There is some humour in the use of the words "winged into The Eagle" in my opinion.
The first national newspaper coverage was in an article in "The News Chronicle" by Ritchie Calder on Friday, May 15, 1953 - which was followed by "Varsity" newspaper on Saturday, May 30th, 1953. The first American coverage was on Saturday, June 13, 1953 in The New York Times, see: http://www.nytimes.com/packages/pdf/science/dna-article.pdf - for a lot more information.
My request for any assistance at all with the mysterious Sunday newspaper article from June 1953 ("During my absence, the first newspaper article that reflected an interview with Francis Crick came out. It was in the Sunday Telegraph and reached a large audience.") is entirely serious, and hopefully we may get an answer from Jim Watson at Cold Spring Harbor Laboratory!
91.110.183.238 ( talk) 16:17, 10 May 2009 (UTC) Martin Packer
Tim,
http://www.nytimes.com/packages/pdf/science/dna-article.pdf - has been added to External Links; can I leave you to add "The first national newspaper coverage was in an article in "The News Chronicle" by Ritchie Calder on Friday, May 15, 1953 - which was followed by "Varsity" newspaper on Saturday, May 30th, 1953." to the text of the article? Thanks a lot, Martin
Nitramrekcap ( talk) 18:26, 10 May 2009 (UTC)
Tim,
I have added the following chronology to the DNA, FRANCIS CRICK, and JAMES WATSON articles:
"The discovery was made on February 28, 1953; the first Watson/Crick paper appeared in Nature on April 25,1953. Sir Lawrence Bragg, the director of the Cavendish Laboratory, where Dr. Watson and Dr. Crick did their work, gave a talk in London on Thursday, May 14, 1953 which occasioned an article in The News Chronicle of London, on Friday, May 15, 1953. The news reached readers of The New York Times the next day; Victor K. McElheny, in researching his biography, "Watson and DNA: Making a Scientific Revolution," found a clipping of a six-paragraph New York Times article written from London and dated May 16, 1953 with the headline "Form of `Life Unit' in Cell Is Scanned." The article ran in an early edition and was then pulled to make space for news deemed more important.(The New York Times subsequently ran a longer article on June 12, 1953.) The Cambridge University undergraduate newspaper also ran its own short article on the discovery on Saturday, May 30th, 1953."
Unfortunately in his "Watson and DNA: Making a Scientific Revolution", Victor K. McElheny quoted Watson's dubious reference the "Sunday Telegraph" (June 1953) rather than mentionning the NYT story of May 16, 1953 - the former did not exist, while the latter definately did!
Nitramrekcap ( talk) 19:56, 10 May 2009 (UTC)
Tim,
Unless we do discover the mysterious Sunday newspaper of June 1953, this is the final version of the timeline for newspapers reporting the discovery of the structure of DNA in May 1953!
"The discovery was made on February 28, 1953; the first Watson/Crick paper appeared in Nature on April 25,1953. Sir Lawrence Bragg, the director of the Cavendish Laboratory, where Dr. Watson and Dr. Crick did their work, gave a talk at Guy’s Hospital Medical School in London on Thursday, May 14, 1953 which occasioned an article by Ritchie Calder in The News Chronicle of London, on Friday, May 15, 1953, entitled "Why You Are You. Nearer Secret of Life." The news reached readers of The New York Times the next day; Victor K. McElheny, in researching his biography, "Watson and DNA: Making a Scientific Revolution", found a clipping of a six-paragraph New York Times article written from London and dated May 16, 1953 with the headline "Form of `Life Unit' in Cell Is Scanned." The article ran in an early edition and was then pulled to make space for news deemed more important.(The New York Times subsequently ran a longer article on June 12, 1953). The Cambridge University undergraduate newspaper also ran its own short article on the discovery on Saturday, May 30th, 1953. Bragg's original announcement at a Solvay conference on proteins in Belgium on 8 April 1953 went unreported by the press!"
Martin
ps I find the Wikipedia article on James D. Watson rather poor - are you going to improve it? —Preceding unsigned comment added by 91.110.174.188 ( talk) 20:56, 10 May 2009 (UTC)
Tim, you're the scientist and I am not (just an enthusiastic amateur with a son who is an MSci, Cantab. and a daughter who is going onto a PhD later this year) but I could have sworn that a timeline about the newspaper coverage of the discovery of the structure of D.N.A. was relevant to an article 'supposedly' about D.N.A.; as you can gather from my non too subtle attempt at sarcasm, I think this "bit too detailed" information should have stayed in the D.N.A. article! Never mind the fact that this is the first time the timeline has appeared on t'internet!! What about re-instating it in an edited form, without too much detail?
Nitramrekcap ( talk) 22:03, 10 May 2009 (UTC)
So why does Maurice Wilkins not get his image in this article? After all, he only shared the 1962 Nobel Prize for Physiology or Medicine with Crick and Watson? His autobiography is not included either! Is the late Professor Wilkins being edited out of 'Wiki' DNA history? RSVP!
|image =maurice_wilkins.jpg |image_width = 200px |caption = Maurice Wilkins
Nitramrekcap (
talk) 22:26, 10 May 2009 (UTC)
The following sentence:
Implies that the Nobel prize now allows posthumous prizes. Is this actually the case? If not the sentence probably needs to be changed. David D. (Talk) 04:12, 22 May 2009 (UTC)
I think that the word "easter" in the text about DNA should be replaced with the word "phosphodiester". This is because (as I have learned) "easter bonds" or "easter linkages" are related to lipids and that the nucleotides are polymerized through phosphodiester bonds/linkages
The title is "DNA"
The text I am talking about sais that the back bones of DNA molecule that are made of sugare and phosphate groups are joined by ester bonds. Livinghappy ( talk) 17:57, 29 May 2009 (UTC)
Ok, than sory! ;-) -- Livinghappy ( talk) 18:31, 29 May 2009 (UTC)
dsDNA is referenced in other articles ( Prokaryotic_DNA_replication for example) but not explained here. A section describing the various acronyms used might be useful. dsDNA, sRNA, scDNA, nDNA, ... Cghislai ( talk) 14:04, 1 June 2009 (UTC)
It would be useful if at least the first reference to the backbone of DNA was linked to Backbone chain. Backbone chain needs to be expanded and linking to it may encourage expansion. I cannot edit this semi-protected page. Daniel.dalegowski ( talk) 21:36, 13 June 2009 (UTC)
The sentence "Within cells, DNA is organized into X-shaped structures called chromosomes." is misleading, as it suggest *all* chromosomes are X-shaped. In the case of telocentric chromosomes, this is not the case. Bowenthebeard ( talk) 18:35, 26 June 2009 (UTC)
Bahh even more misleading. Chromosomes are only X-shaped for a brief while right before cells divide. The well known X-shape is actually two copies of the same chromosome stuck together in the center at the centromere. When the cell divides, the X-shaped structure splits into the two individual straight chromosomes, and one goes to each daughter cell. See wikipedia article on mitosis.-- 66.27.75.3 ( talk) 03:58, 7 August 2009 (UTC)
Is it really necessary on this article? The IP activity did not look too bad, and I would like to edit the text some, but not by posting here. Can the semi-protection be removed? -- 69.226.103.13 ( talk) 07:29, 29 June 2009 (UTC)
MINOR SUGGESTIONS: I would recommend 2 slight changes. In the first, I would suggest inserting "deoxyribose" in front of the word "sugars" in the description of the general structure of DNA (Chemically, DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds.) In addition, nucleotides consist of more than bases. I would suggest revising the following sentence: " These nucleotides are adenine (A), guanine (G), cytosine (C) and thymine (T)." Instead you need to state that nucleotides consist of 1 to 3 phosphate groups, a deoxyribose sugar, and one of four bases: adenine (A), guanine (G), cytosine (C), or thymine (T). Gudelskj ( talk) 00:27, 3 August 2009 (UTC) Gudelskj,8/2/2009
In the introduction section it says, "DNA is often compared to a set of blueprints, or a recipe, or a code..." This is incorrect because DNA is not like a set of blueprints. If it is often compared to that then it must be cited who says it, and it should be from reputable sources (i.e. scientists that work with DNA). Richard Dawkins has stated several times in several different books that DNA is not like a blueprint. For example he states this is in The Ancestor's Tale, The God Delusion, and A Devil's Chaplin. He and others do agree that it is like a recipe, computer code (like binary language), or a toolbox of computer subroutines.
I will give it a little time for someone else to make the change or I'll change it to reflect my previous sentence. I hope that someone might be able to write it a little more eloquently than me.
XXVII ( talk) 05:40, 27 August 2009 (UTC)
You really are over reacting to a helpful metaphor. At an advanced level, an instructor can have the kind of discussion with students about A,G,C and T, and how the genetic code is very simple, very lengthy and yet effective. But that does NOT remove the effectiveness of the "blueprint" metaphor. To a newer student, explaining DNA as a blueprint is good enough. It helps him or her understand the basic function, which they may learn in increasing complexity over time. —Preceding unsigned comment added by 69.20.169.7 ( talk) 04:19, 8 October 2009 (UTC)
DNA is not a program. It is not even know how a protein gets its tertiary or quaternary structure. DNA just code the aminoacid sequence of a protein, and no more.
The problem of the comparison goes in more important conceptual scientific issues that those fanatic ideas in which just some religious fundamentalists are obsessed with intelligent design.
The main problem is that it oversimplifies the notion of life. A living organism is not the realization of blueprints coded in DNA. There is more than that in the development process. Epigenetic issues are often neglected, that factors are as important as the genetic ones. What kind of factors? well, many I should say, like the coordination between proteins and other molecules in the cell. The comunications between cells. The diffusion rates of messages, metabolic molecules and other factors in the physical environment.
When someone talks about blueprints, is adopting a preformationist position, line that sketched in the famous homunculus picture. It puts the discussion of vitalism vs. preformationism in the table.
Researchers in developmental biology, take into account both sources genes and physical factors.
For that reason I do not agree with the person who said that it is an over reaction for a helpful metaphor, because this metaphor just leads to a complete wrong idea of how the thinks work. DNA does not look like a computer program, maybe just as data to build some proteins self organized in metabolic, signaling, ..., pathways machines. Why? because the physical-chemical environment allows and even cast them to interact in such way and they survived to many oddities, being able to be replicated and inherited to descendants or transfered to other organisms (by horizontal transference, for example).
The problem is very complex, in the sense of non-linear systems. Where the behavior of the whole system is not explained just by the isolated behavior of their parts. That is a common place in science, but a not deeply understood issue for many scientists.
As you can see, this issue goes further that just the obsession of Dawkins against pseudoscientific theories from religious fanatics. I would say that that point should at least say it is a "... often wrongly compared ...", because the "often" mentioned by Tim Vickers is not enough.
Please, place more attention to this issue, as it is very common in the tv and written press to hear about things like the gen of madness, the gen of diabetes, the gen of heart attack, the gen of egoism, the gene of ..., which of course is a wrong conception whose source I ignore. Let us extirpate such misconception of general population interested in the subject. Specialized scientist, know that the things work in a more complex way that such metaphor says. There are no magic genes like those in the Hollywood movies. Susan Oyama, has a book on the subject of preformationism vs. vitalism in contemporary scientis, (I do not remember the title at this time). Take a look on it. —Preceding unsigned comment added by Elias ( talk • contribs) 22:25, 19 November 2010
There are people who believe that not all life requires DNA, and that life outside Earth could exist wthout DNA. For instance, in 2001 there were reports about red rains of Kerela being composed of foreign microbes. The question of life without DNA is currently being discussed for the proposed class of nanobacteria. [3] [4] Also, there was a strange report in 2009 in Mexico about a baby alien who didn't have DNA. [5] ADM ( talk) 09:32, 27 August 2009 (UTC)
I refer to the butchering a of a whole sourced sentence just because someone didn't think it was too short for the introductory passage. If you think you are such a pinnacle of wikipedia at least incorporate it to the rest of the article. Don't destroy the hard work of individuals just because you personal aesthetic view of the article doesn't agree. I'd expect more from people versed into DNA an evolution (a process filled with improvement, not returning to the drawing board). -- fs 16:52, 3 November 2009 (UTC)
Under the "Properties" category, it states that DNA is stabilized by hydrogen bonds. However, under the "Base pairing" subcategory, it says hydrogen bonds only provide specificity for the pairing, and not stability. I think the latter is correct, and it should be edited. 24.201.152.230 ( talk) 03:04, 12 November 2009 (UTC)
No matter what Wikipedia policy may be, an article about DNA without a picture of Rosalind Franklin is not acceptable. Also by taking her out of the gallery, you diminish her contribution to the discovery of DNA by only listing the men who took / interpreted her work. Please consider this and show some good faith instead of just blindly removing the picture again due to some Wikipedia policy. I hope we can come to some kind of agreement here. Greetings -- hroest 08:30, 15 November 2009 (UTC)
I do not know what policy was argued to support the removal of Rosalind Franklin from this page, but Franklin's work was substantial to the discovery of DNA structure, she is not mentioned too much, because she did not received the Nobel Prize, because it is not postmortem. But nobody can neglect her important contribution. I agree with Hannes Röst, that Rosalind Franklin picture should appear in this article, more over, linked to the entry about her. —Preceding unsigned comment added by Elias ( talk • contribs) 22:25, 19 November 2010
Can someone add the IPA phonetic pronunciation for deoxyribonucleic to the article. Carlwev ( talk) 15:05, 20 January 2010 (UT
Thank you for your help and the audio file. I shall add this to the top of the article; matching other articles especially those with difficult words.
()
Carlwev ( talk) 15:11, 11 February 2010 (UTC)
Can DNA be thought of as a database ? —Preceding unsigned comment added by 59.103.212.144 ( talk) 15:13, 13 February 2010 (UTC)
I don't know if this answers your question, but a well known computer guy (adelman, of RSA security) started teh field of DNA computing; there is a ref in the acrydite article Cinnamon colbert ( talk) 01:27, 27 October 2010 (UTC)
I don't see how an animation of DNA spinning is beneficial to understanding the structure of the molecule; no matter how pretty the image is. The animation catches the eye of the average reader yet explains nothing. Looking through the commons I couldn't find an image that I thought was suitable, but if we can come to consensus on what the lead image should be, I'd be more than interested in attempting to create said image if it doesn't already exist.-- Ben Harkness ( talk) 00:31, 20 February 2010 (UTC)
A graphic in the
DNA#Genetic_recombination section shows A-G and C-T pairs throughout, as if recombined
chromatids differ as much as antisense strands of DNA. But chromatids M and F should be
homologous before recombination, right? I don't believe that fertile parents of the same species might have genetic codes so completely different.
Prari (
talk) 03:15, 14 May 2010 (UTC)
The article uses the word 'information' several times when discussing DNA, yet there is no metric for determining whether DNA has any 'information,' let alone how much. There are several science papers discussing the issue of 'information' in DNA, and most of those are considered controversial due to the lack of such a metric. Attempts by some scientists to show DNA has 'information' have not been convincing, and are often refuted by other scientists. I suggest a different word be used instead of 'information' when discussing DNA. -- Desertphile ( talk) 22:15, 25 May 2010 (UTC)
I don't know if this issue has been discussed but I noticed that James D. Watson's photo is not present in the history section of this article. I am raising this concern because Watson was the first author (followed by Crick) of the Nature paper. Omitting his photo but including photos of Franklin, Crick, and Gosling (I don't know why there is one of him) in the History section doesn't seem quite right to me. In my humble opinion, I think a picture of both Watson and Crick admiring their DNA model should substitute the photo of Francis Crick. Any thoughts? mezzaninelounge ( talk) 21:44, 24 August 2010 (UTC)
I couldn't agree more; to have a DNA 'article' without images of Watson and Wilkins is ridiculous!
The wording on the DNA sculpture (which was donated by James D. Watson) outside Clare College's Memorial Court, Cambridge, England is:
On the base:
"These strands unravel during cell reproduction. Genes are encoded in the sequence of bases."
"The double helix model was supported by the work of Rosalind Franklin and Maurice Wilkins."
On the helices:
"The structure of DNA was discovered in 1953 by Francis Crick and James Watson while Watson lived here at Clare."
"The molecule of DNA has two helical strands that are linked by base pairs Adenine - Thymine or Guanine - Cytosine."
— Preceding unsigned comment added by 91.110.208.91 ( talk) 03:19, 5 September 2010
There has been an extensive discussion on the Talk:Science of what the lead definition of the science article should be. I suspect this might be an issue that may be of interest to the editors of this page. If so, please come to the voting section of the talk science page to vote and express your views. Thank you. mezzaninelounge ( talk) 16:10, 18 September 2010 (UTC)
{{
edit semi-protected}}
"The two strands run anti-parallel to each other" in the first section should me changed to "The two strands run parallel to each other" as in a double helix, when unraveled such as when a transcription to DNA begins, the two strands are parallel.
Xforty ( talk) 08:07, 28 September 2010 (UTC)
Thanks :) I learnt something too! —Preceding unsigned comment added by Xforty ( talk • contribs) 02:00, 24 October 2010 (UTC)
"The DNA double helix is stabilized by hydrogen bonds between the bases attached to the two strands" Inter strand H bonds provide part of the energy; more is provided by base stacking, which is seq specific, eg the duplex of GGGCCC is less stable then the duplex of GCGCGC, because stacking energy is most favorable for G,C steps Cinnamon colbert ( talk) 01:08, 27 October 2010 (UTC) The inaccuracy is partially repeated here The two types of base pairs form different numbers of hydrogen bonds, AT forming two hydrogen bonds, and GC forming three hydrogen bonds (see figures, left). DNA with high GC-content is more stable than DNA with low GC-content, but contrary to popular belief, this is not due to the extra hydrogen bond of a GC base pair but rather the contribution of stacking interactions (hydrogen bonding merely provides specificity of the pairing, not stability).[16] As a result, it is both the percentage of GC base pairs and the overall length of a DNA double helix that determine the strength of the association between the two strands of DNA.
It is not just G,C content, but sequence; the GC/CG is much more stable the GG/CC. ref 16 in the article is good, but work by Tinocco or someone like that would be better. Cinnamon colbert ( talk) 01:25, 27 October 2010 (UTC)
I made an account today simply to make this point, I am glad you already did. The vast majority of DNA stability is provided by base-stacking interactions from by the hydrophobic nucleotides. They orient at an angle almost perpendicular to the axis of the DNA. I don't know where to find reliable sources but I am looking at a biochemistry textbook right now that says what I just typed. Please someone fix this. I would but I know very little about how to edit wikipedia. Ds2207 ( talk) 17:12, 1 November 2010 (UTC)
Update: http://nar.oxfordjournals.org/content/34/2/564.short This journal article supports that base-stacking interactions contribute much more thermodynamic stability at neutral pH vs. hydrogen bonding between base pairs. Ds2207 ( talk) 17:16, 1 November 2010 (UTC)
{{ Edit semi-protected}} Please correct the spelling of the word "axis" in the second sentence of the "Properties" section.
Change from:
....As first discovered by James D. Watson and Francis Crick, the structure of DNA of all species comprises two helical chains each coiled round the same access, ....
to:
....As first discovered by James D. Watson and Francis Crick, the structure of DNA of all species comprises two helical chains each coiled round the same axis, ....
75.40.216.62 ( talk) 16:09, 12 November 2010 (UTC)
Suggest entire alternate DNA structure section be rewritten from scratch to include arsenic backbones in light of new research published today. —Preceding unsigned comment added by 64.124.22.9 ( talk) 19:00, 2 December 2010 (UTC)
Agreed; this is a HUGE finding. See these references:
The discoverer of this bacteria is Doctor Felisa Wolfe-Simon. Her website is this:
I just created a new sub-section in this article, Alternate DNA chemistry. Much of the exact text I used was borrowed from other material recently contributed to other Wikipedia articles. The problem with all those new (and useful!) contributions) was that they were scattered around several articles. This article, instead, seems the logical place to bring together and summarize the basic information. Details (which will certainly run to several pages) may then develop on other pages linked to this one. RK ( talk) 18:02, 3 December 2010 (UTC)
I edited the section for several reasons:
Unconventional ( talk) 18:21, 6 December 2010 (UTC)
Everybody's too upset with that arsenic thing -> moreover: These bacteria were not grown on arsenic but on an arsenate medium, that's one important difference —Preceding unsigned comment added by 92.206.179.22 ( talk) 18:21, 10 December 2010 (UTC)
Could someone please remove the following silly sentences:
"DNA was discovered by Rosalind Elsie Franklin. However one of her neighboring scientists in the lab, Maurice Wilkins showed her photos without permission to Watson and Crick. She tried to beat them in getting DNA's structure and composure but they had overcome her."
Why not at least link her name in the article to her wikipedia article? Eric.rodd ( talk) 14:29, 21 March 2011 (UTC)
This article mistakenly implies that DNA is fully stabilized by Hydrogen bonding between base pairs, but recent science has shed more light on the subject. Far more stabilization comes from the reduction in Gibbs free energy due to base-stacking interactions which occur largely because the aromatic rings on the nucleotide bases are hydrophobic. It is in fact partially stabilized by hydrogen bonding but I wish the article to better reflect the true environment in the cell. You can read more at Stacking (chemistry). I am a undergraduate student at Michigan and I have heard this reiterated in multiple biochemistry lectures. I would like either permission to edit, or one of you Administrators who can edit this article to make the relevant changes. Here are my external Wikipedia-compliant sources:
Ds2207 ( talk) 00:10, 24 February 2011 (UTC)
"Far more stabiliation comes from" base stacking? Wouldn't the Tm values for DNA melting be pretty similar between AT rich and CG rich be quite similar if that was the case? I'm sure base staking contributes to the stabilization but I'm a little dubious that it dominates. David D. (Talk) 17:59, 25 February 2011 (UTC)
Yeah, I see what you're saying. I can't find any papers that give the absolute reduction in Gibbs free energy of base-stacking vs base pairing. The thermodynamic calculations of DNA are a little above me. Still, the annealing temp difference of AT rich vs CG rich area's is not that great. See Nucleic acid thermodynamics. Again, all I can say is that I've learned within the last year that base stacking predominates and the source I cited supports that. Thanks for bringing your concerns up. Ds2207 ( talk) 19:06, 8 March 2011 (UTC)
The article states 'DNA with high GC-content is more stable than DNA with low GC-content, due to the added stability of an additional hydrogen bond." However, I think its now thought that the primary force holding DNA together is not hydrogen bonding, but base stacking. See, for example, this review by Kool: "In general, recent data with DNA alone (in the absence of enzymes) suggests that hydrogen bonds contribute strongly to the selectivity of DNA base pairing in DNA alone. The bonds also appear to contribute to pairing energetics favorably, although with only moderate magnitude. It is possible to design nonhydrogen- bonded pairs that are somewhat selective and that are at least as stable as natural base pairs. From the steric standpoint, it appears that steric effects may affect base pairing preferences somewhat, though the influence may be moderate. Finally, stacking effects are probably the major influence of base pair stability and are the major force holding the double helix together. " ("HYDROGEN BONDING, BASE STACKING, AND STERIC EFFECTS IN DNA REPLICATION" - http://www.annualreviews.org/doi/abs/10.1146/annurev.biophys.30.1.1) —Preceding unsigned comment added by 66.31.200.53 ( talk) 04:43, 17 March 2011 (UTC)
Under "History and anthropology":
"This can be used in studies ranging from ecological genetics to anthropology; For example, DNA evidence is being used to try to identify the Ten Lost Tribes of Israel.[135][136]"
I fail to see how this is an example of either ecological genetics or anthropology. The "Ten Lost Tribes" topic is more closely linked to such subjects as theology and Christian-funded Biblical archaeology (not quite mainstream anthropology). DNA studies, however, are very important in biological anthropology (eg. understanding human genetic diversity) and archaeology (migration histories through mtDNA). Sorry to just come in here and complain and not fix anything but I just noticed a glaring inconsistency and (hopefully) suggested a way to fix it. —Preceding unsigned comment added by 66.25.129.229 ( talk) 02:38, 26 March 2011 (UTC)
You lack a section on H-DNA/Triplex DNA. Triplex DNA is implicated in gene regulation and mutagenesis. This seems to be a glaring deficency!
Sincerely,
Alan Kinniburgh, Ph.D. —Preceding unsigned comment added by Big al123 ( talk • contribs) 18:56, 6 May 2011 (UTC)
Good Wiki practice dictates that history of a subject belongs at or near the start. Twobells ( talk) 18:54, 6 July 2011 (UTC)
There's already a lot in the EL section, but I thought I'd point editors here to this excellent animation in case you think it merits a mention. http://www.wehi.edu.au/education/wehitv/body_code_drew_berry_2003/ There are more by the same institute at http://www.wehi.edu.au/education/wehitv -- Anthonyhcole ( talk) 11:50, 16 July 2011 (UTC)
This
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hi there, i would like to point out an error in the citations, it is now:
141 Astbury W, (1947). "Nucleic acid". Symp. SOC. Exp. Bbl 1 (66).
but it should read: 141 Astbury W, (1947). "Nucleic acid". Symp. SOC. Exp. Biol. 1 (66).
so "Bbl" has to change to "Bbl" because it is called the "Symposia of the Society for Experimental Biology". The reference points to a section within DNA History. You can find the correct references for instance in the Paper "Molecular Structure of Nucleic Acids" 1953 by Watson & Crick.
Thanks for your patience, skund
Skund ( talk) 13:32, 19 July 2011 (UTC)
I think that Richard Dawkins has raised issues with the use of the term blue print for DNA in a recent book (please add the reference if you know it). A blue print supports two way information (a blueprint can be constructed from observations of a house and a house can be built using blueprints for instructions). However, with DNA is would appear not to be feasable to construct a segment of DNA even if we new the protein for which it coded. The first paragraph of this article says:
"DNA is often compared to a set of blueprints, like a recipe or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules."
Because of this critisism of the analogy I think it should be removed from the article.
ManinStone 2.219.126.222 ( talk) 12:36, 1 August 2011 (UTC)
I agree. The DNA molecule is not a set of blueprints. DNA is a molecule that does nothing more than chemistry; it reacts with components found in the environment. It is wrong to compare DNA to something that stores information, such as a blueprint, book, recipe, or computer code.
Nursebhayes (
talk) 20:36, 19 August 2011 (UTC)
<<<"please add the reference if you know it">>>
The Blind Watchmaker Nursebhayes ( talk) 20:44, 19 August 2011 (UTC)
Perhaps blueprint is not the best analogy. But just because Richard Dawkins doesn't like it is not a reason per se for not using it as one. DNA does store information and the science bioinformatics has been built on this. It is not true to say "it is wrong to compare DNA to something that stores information". DNA does. I see no one has offered a better analogy. Graham Colm ( talk) 21:14, 19 August 2011 (UTC)
Dawkins has this to say on the information carried in DNA:
"It is raining DNA outside. On the bank of the Oxford canal at the bottom of my garden is a large willow tree, and it is pumping downy seeds into the air. ... [spreading] DNA whose coded characters spell out specific instructions for building willow trees that will shed a new generation of downy seeds. … It is raining instructions out there; it's raining programs; it's raining tree-growing, fluff-spreading, algorithms. That is not a metaphor, it is the plain truth. It couldn't be any plainer if it were raining floppy discs." The Blind Watchmaker (1986). Graham Colm ( talk) 21:31, 19 August 2011 (UTC)
I think removal was not the best response here. The part removed read "The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints, like a recipe or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules." The first sentence was right on, and is much better than what the lead now says, since "information" is more correct and neutral then "instructions", which is another misleading analogy. The blueprint analogy is not a great one, as Dawkins discusses, but it's true, I think, that it's often compared to; and it did speak of recipe, and very low-level pieces, so it wasn't even carrying the blueprint analogy very far in a bad direction. So, maybe not in the lead, but someplace, why not talk about it, so we can better describe how the "information" in DNA actually works? Disclaimer: I haven't read the rest of the article, so maybe it's already in there. But how about we change instructions to information in the lead at least? Or put back "The main role of DNA molecules is the long-term storage of information."? Dicklyon ( talk) 04:05, 24 October 2011 (UTC)
hello, are you doing a school project well try this. list what DNA stands for deoxyribonuclacic acid!!! wow thats alot. ok theyn write the def. somethng like contains general instruction of living organisums. HOW TO DRAW DNA- sirst start with a sqiwgaly line with wide squwigalies, theyn do another but semetric to the other one! theyn fill it in with small lines. Well i guess thats it. (these directions my vary due to the directions of you teacher(professer,ect.)) — Preceding unsigned comment added by 74.167.40.38 ( talk) 22:56, 19 September 2011 (UTC)
In the first DNA picture, a ball-and-stick model
DNA Structure+Key+Labelled.pn NoBB.png
there is an inset showing blowups of two consecutive base pairs in the main picture. The lower base pair CG is correct but there is a problem with the upper one. In the blowups, the upper pair is TA, but in the main molecule it is GC. The upper base pair in the main molecule should be redrawn to make it consistent with the blowup. (The next base pair up in the main molecule is indeed TA, but it is not angled conveniently). Alternatively, one might redraw both main molecule and the upper blowup to be AT. This would have the advantage of showing that the double helix can accommodate base pairs in any orientation, i.e. with either the purine or the pyrimidine on either strand, without distorting its overall shape. CharlesHBennett ( talk) 18:44, 20 September 2011 (UTC)
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Please change following sentence:
"Polymers comprising multiple linked nucleotides (as in DNA) is called a polynucleotide.[9]" to cause agreement of subject which is plural with verb. Please change "is" to "are".
74.176.211.13 (
talk) 22:14, 14 October 2011 (UTC)
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"Independent conformation of this finding has also not yet been possible" should be confirmation, not conformation
188.111.66.160 ( talk) 10:53, 8 December 2011 (UTC)
Hi, i can't edit the page but the picture has an incorrect file name, I spotted it when i was doing my Research. (Mahamed Ali 16:13, 9 January 2012 (UTC)) — Preceding unsigned comment added by Mahamed90 ( talk • contribs)
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Please add a link in the 'See also' section to the page DNA-encoded_chemical_library, as it is currently an orphan.
Charon77 ( talk) 05:35, 29 December 2011 (UTC)
Please correct the article category mapping: it’s in the physical category "Scattering", which has nothing to do with its topic (biology, DNA and so on...) Theafh ( talk) 23:23, 17 January 2012 (UTC)