Watson & Crick In 1953

watson-and-crick-1953In their 1953 “Molecular Structure Of Nucleic Acids” Watson and Crick open with the decidedly unscientific “We wish to suggest…” and in only a short page or so, take us through their thoughts on what shape DNA takes in the natural world. With a tone, that is though decidedly academic, conversational in the way it winds from chemistry to other laboratories take on what structure DNA might take. The paper is notable for what is not present as well. After a careful description or at least inventory of the facts supporting their structure, they proceed to open up a new avenue of discusion; suggesting how the model might relate to the observed biology. In one of the final paragraphs they lead with “It has not escaped our notice…”. They hint that the structure they have described, suggests that there is a very simple solution to another vexing problem remained unsolved in 1953. How does DNA copy itself, and how does it do so quickly?

Here Watson and Crick speculate that they have solved an important piece of this puzzle, and interestingly do so without directly stating what their speculation is! As is to pass off the impoliteness they assure us that these speculations and more data will follow.

They write as if they are having a conversation with you, an old colleague. When in fact they seem to have carefully crafted their thoughts so the reader can follow the unfolding story as if discovering the structure themselves.

For your first assignment I want  you to compose a paragraph or two, describing your scientific response to the idea that DNA is an anti-parallel double helix. Write for a broader audience, not just scientists. Explain why this discovery is important, not from today’s perspective, but how you imagine a scientist in 1953 might respond.

52 thoughts on “Watson & Crick In 1953

  1. The double-helix? That’s quite far fetched but if you don’t run out on your “copying” ideas then my hat is off to you sirs. With such replication who knows where human limitation has to halt. Think of it: if an arm or leg were to be tragically taken from some one with a quick retrieval, maybe a bit of ice, and your replication his arm might become better than ever.
    How does the Deoxy-Ribonucleic Acid get energy for all this twisting you talk about. There must be some proteins at the end of each 5″ and 3″ end to tell the DNA where to go. What to do and how to do it. Regardless if most of what you say is true they might rename the Nobel prize after you two.

  2. Pieces to a puzzle!
    A spontaneous leap in the field of science as one may call it! The discovery of DNA has finally been pieced together. The Medical Research Council Unit of Study of the Molecular Structure of Biological Systems, Cavendish Laboratory in Cambridge is where the proposed ideas of Watson and Crick has become the birthplace for scientific revolution. This advancement in science is rather an extraordinary exciting time for not only the science community, it reflects in the lives of all man kind. After much speculation of the evidence presented in the April 25th edition of Nature they seem rather definitive in their disclosure of their proposed structure of DNA. In my expertise, I have never seen such work as diligently presented as this. It lucidly spells out the that the double helix model is in fact wrapped around the axis as bases are sequenced, running in opposite directions.
    In every respect DNA is the foundation to all life. The culminating report by Watson and Crick rightfully undermine Pauling and Corey’s observations regarding the hydrogen bonds along with the purine and pyrimidine bases which hold the molecule together is eloquently written. It is in our best interest to understand the depth of research that has been undergone to bring us to this celebratory climax. I believe this momentous victory will forever establish a mark for generations to come. We have undoubtedly uncovered a treasure, now it is time to decipher the meaning behind it.

    • I also want to add that the bases are joined together in pairs one of hydrogen and one of other. Pauling and Corey made their point that only certain pairs of bases will fit into the structure. One being of purine pair and other of a pyrimidine, to connect them together. So in other words both pairs can’t be of purines only.

    • I really like the title of your response, i feel that it summarizes everything in just those few words. Indeed, i do agree with you when you mentioned that this scientific advancement affects all man kind. With this discovery, people everywhere will be more educated about themselves. This scientific advancement is something that doesn’t only affect the scientific community, but all of us. I really like that. Also, i enjoyed the way you ended your response because you basically opened a new chapter that wants readers to know the answer to the question “what happens now?. Your words conveyed your emotions very well. .

  3. I will be writing on the part of Genetical Implications of the structure of Deoxyribonucleic Acid. Watson and Crick did a good job on proving how the deoxyribonucleic acid molecule can duplicate itself. They explain the molecule of deoxyribonucleic acid has a backbone, which consist of regular alternation of sugar and phosphate groups. The sequence of sugar base along the chain is irregular since sugar is attached to four different types of nitrogenous bases.

    One of the aspects of their structure was that it consists of two chains, and the two chains coiled around a common fiber axis. This is proven by the experiments done with x-ray that suggests of two chains. In their theory they also explained that the chains are also held together in a manner that suggests the same, and it is done by hydrogen boding between the bases. Watson and crick’ study also shows that only certain pairs of bases are the fit in the structure.

    They went on to explain that one member of a pair must be Purina and other has to be pyrimidine in order for the chain to be held. To prove their theory they have given an opposite side of what will happen if the structure is consisted with only one chain. If bases will be present in tautomeric forms then the case will be that hydrogen bonding will be restrictive and only possible pairs will be Adenine with Thymine and guanine with cytosine.

    Phosphate-sugar backbone is completely regular and any sequence of the pairs of bases can fit into the structure. In a long molecule many different permutations are possible, hence the precise sequence of the bases is the code carries the genetical information. So if the bases on one of the pair were given one can write down exact order of the bases of the other one. That is possible because of specific pairing; it proves that one chain is complement to the other.

    • I think that it is a good start by saying they have something by having matching bases and the phosphate sugar backbone but where the proof. Why don’t they explain how they have stumbled upon this remarkable discovery.Do they have any theories to test this paring. What happens if one pairing is off?

  4. As Watson and Crick suggest that one of the unexpected features of the structure for Deoxyribose Nucleic acid is that the “two chains” are bounded by purine and pyrimidine bases, and the “two chains” must have opposite polarity in order to stay in place. More specifically, what I meant by opposite polarity is that one base has to attract to another base accordingly. In addition, it has also been noticed that Watson and Crick have assumed that the “two chains”, which turns to be two ribbons shown on the figure, are oriented into two opposite directions. In depth, if one chain moves in a 3’ to 5’ direction, the other must undergo from 5’ to 3’ as this suggestion will be compliant with Watson and Crick’s hypothesis- “if the sequence of bases on one chain is given, the sequence on the other chain is automatically determined.” (737).
    Another feature that Watson and Crick have boldly suggested is that the structure of Deoxyribose Nucleic Acid is an “open one” (737). Nevertheless, I would rather call the structure an “unzipped zipper” based on figure.2. (965) as pairs of bases on the side are arranged neatly in rows and perpendicular to the fibre axis. And if that is the case, just imagine it this way: would the structure still be manageable without the fibre axis standing straight in the center.

    • As you have stated, most of everything Watson and Crick wrote were all based on assumptions. If they were to provide more solid evidence I believe it would make it easier to agree with their paper. Also, I like the way you disproved Watson and Crick’s “open” DNA structure by asking “would the structure still be manageable without the fibre axis standing straight in the center?”

  5. This model certainly is quite marvelous in its simplicity. A double-helix with a phosphate backbone and a 2 pairs of repeating base pairs. The part of this discovery that forces me to accept this structure is the fact that the structure is so chemically efficient, that forces me to see this model as the truth we have been looking for. From the phosphate backbone to the cis-trans base pairs the model is so logical and chemically valid. I feel that with this model we should be able to push further in biology maybe even change the way we see biology in the coming years. I expect this model to make great stretches in the coming decade as a blueprint for more studies regarding Genetics, Cells and possibly even in relation to illness.

    • Although I’ve never thought about how DNA can actually be related to illness, I do appreciate how you consider Watson and Crick’s Deoxyribose Nucleic acid model as the foundation for the Genetics studies. For example, mutations of DNA are found to be the cause of several illnesses such as cystic fibrosis. Furthermore, I do agree that Watson and Crick’s significant discovery on DNA has contributed greatly to the field of scientific inquiry, genetic studies in partcular.

      • On illness, there are many diseases that we do not yet understand and can not cure. With this model we may be able to look at cells with a different perspective possibly finding out how other infections spread possibly by looking at DNA and using this model as a template to compare the DNA of infected and uninfected cells.

  6. Remarkable! This discovery is quite extraordinary. Who would have ever thought that the structure of Deoxyribose nucleic acid would be a double-stranded structure? Not to mention that it would be discovered by no other than our very own Watson and Crick. With this movement in the scientific community, who knows what other phenomenon we can soon come to know. I appreciate Watson and Crick’s efforts to fully explain all of their scientific results and comparisons. For example, instead of just simply calling Pauling and Corey’s work “unsatisfactory”, they went into detail on why their structure could not work and they further advance and prove why the structure should be a double helix. Noteworthy is what I call it. They were able to construct a model exhibiting and proving how DNA is structured. Moreover, I would like to emphasize what seems to be understated in the article itself. Postulating the idea of the specific pairing sequence enhances our understanding and immediately suggests “a possible copying mechanism for the genetic material”.
    Again, Watson and Crick bring substantial evidence to the table for the scientific community. It is only the beginning to what comes next as we gather more evidence to prove the remarkable evidence that lies behind the mechanism of DNA. My personal implication relies heavily on the evidence that can now be deemed valid and begin to move forward. I certainly do not undermine the discoveries of Watson and Crick to say the least. It cannot be stressed enough that we have reached a milestone.

    • I agree with this that Watson and Crick’s achievement in the discovery of the double helix of DNA was a milestone and a great discovery and yet only the beginning. More evidence needs to be collected to prove this theory, because what they have used as evidence is just the surface of what needs to be discovered about this puzzling and fascinating structure, DNA that will help to explain the genetics of both humans and animals in the future.

      • I completely agree a lot more research needs to be done on DNA before we can definitively say we understand DNA. More research needs to be done on the phosphate backbone, base pairs, and on how DNA works in general. There is a way that DNA transfers information and produces the genetic code that makes us who we are.

  7. DNA, although previously believed to be triple stranded by L. Pauling and many others is refuted by Watson and Crick in their articles about the structure of DNA. I believe that Watson and Crick are correct in assuming that the struture of DNA is actually a double helix, because DNA is semi-conservative and therefore it would make sense that each strand from DNA comes from each parent. The diffraction patterns that Watson and Crick were given to by R.Franklin and M. Wilkins further proved that the structure of DNA was in fact helical and is the evidence that Watson and Crick used to back up what they believed. They believed that the interpretation of the diffraction patterns were incorrect and instead believed that what was suppose to be the free acid was actually the salt, which makes the struture unclear since the repulsion from the phosphate group would never stay attached to the DNA unless the structure was helical.

    • I agree with you on how Watson and Crick’s model is definitely more plausible than Pauling’s triple helix model. However, more evidence is needed to show that their structure is the correct one, and they did not provide this evidence. Also, I do not believe that they meant that one strand came from each parent. Each strand in a DNA molecule is complementary to the other strand according to the base pairing rules.

  8. In response to the scientific paper submitted by Watson and Crick on Deoxyribose nucleic acid structure. This is quite a statement that is being made; our original idea was the DNA was composed of a tri-helix structure. The evidence put forth by the scientists is convincing, especially the crystallized x-ray put forth by the two men. On the other hand I do see how the double helix makes sense, with the base pairs in the middle surrounded by a phosphate backbone. It now makes sense that the base pairs would connect through nitrogen bonds to create this double helix. I do find it a little too simple though, I question what is going on while DNA is not at a motionless picture. The two stands must be anti-parallel if they weren’t the DNA strands would try to separate away from each other. That is why there is a 5prime, and a 3prime stand that are inversely put together. This is a great start on discovering DNA and all of its aspects; this is definitely not the end of our studies. I credit Watson and Crick and all of those who aided such as Roselyn Franklin in the discovery of the DNA structure.

    • I think Pauling’s ideas about DNA being a tri- helical structure was more complex than Watson and Crick’s double helical structure. I agree with your statement, that the double helix model is a simpler concept to understand than Pauling’s tri- helical structure. Pauling didn’t have x-ray images or accurate data to prove DNA was a tri- helical structure. Watson and Crick’s evidence is stronger since they provided the crystallized x-ray.

  9. Firstly, I would like to say that the structure for DNA proposed by Watson and Crick is certainly plausible. The chemistry of their structure is much more stable than other models that have been proposed. I believe that they are correct in their assertion that Linus Pauling’s model of a triple helix with charged phosphates on the inside of the molecule makes no sense chemically, because the negative charges would repel each other, as they have stated in their paper. Their model of a double helix with the charged phosphate groups on the outside seems to be more credible. Also, a double helix makes more sense than a triple helix because of the evidence of Chargaff’s rules of base pairing. A pairs with T in the double helix, and C pairs with G
    However, I must point out the lack of quantitative data in this paper that led Watson and Crick to their proposed model. Aside from the model being chemically plausible, which has been ceded, there is little to no solid evidence that they can bring forth. For example, they speak of the length of DNA between nitrogenous bases, but offer no explanations as for how they arrived at those numbers. Their model is certainly something that can be expounded upon with future work, but in my opinion, the structure of DNA is still uncertain. Until all of the data is compiled and properly examined, the model for DNA structure cannot be given definitively. Also, they should be a little more clear on what they mean by the replication mechanism that seems to be inherent in their proposed structure.

    • I agree with you that this paper is very formal and that more experimental data would have been more influential for this paper. I am also very weary of the validity of their claims. As for now though their model is the best in the way of satisfying the data already known for DNA.

  10. Kareem Daley

    The structure proposed by Watson and Crick is very interesting; it satisfies a lot of the empirical data gathered on DNA and also suggest a mechanism for replication.The double helix seems to be the best structure when backed by the experimental evidence such as the certain bond types in key places, specific base pairing of purine to pyramidian to satisfy the measured lengths, and the ratio of specific bases being close in count. Linus Pauling’s model of a triple helix was very flawed especially in its location of the phosphate groupes witch would through off the charge balance within the molecule. Also the ratio’s of the bases A-T and C-G would be violated because instead of base pairs you would have base triplets.

    • I definitely agree with you. This model is not only simpiler than the others that were proposed but also agrees with all the data so far, thus making it the best model we have seen. I think it was rather skilled handiwork for Watson and Crick to get all these experimental values and put them together into the model.

  11. Watson and Crick’s discovery of the DNA structure being a double helix is indeed a breakthrough, their discovery can help explain how genetic material passes from generation to generation. This means DNA is the carrier of the genetic code. This knowledge of how genetic material is stored and copied will lead to new discoveries such as manipulating biological processes, in the future pieces of DNA can be cut and inserted at different places. This information will help us understand the role of different genes that function in human and animals. The crystallized x-ray revealed the helical structure, which was in the shape of an “x” The structure of the double helix is somewhat like the rungs of a ladder. DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Franklin should be credited along with Watson and Crick because her famous photograph which had been crystallized revealed the structure of the DNA, which was shaped like an “X”.

    • I agree with your example of comparing DNA to a ladder. It looks similarity like a ladder that is twisted. This discovery will definitely led to discoveries in science like you stated above. More research is still required to truly prove that this theory is correct. Definitely Watson and Cricks model is more simplistic and they have provided evidence.

  12. Watson and Crick are definitely making a big claim in publishing this paper and if true a huge advancement in the field of science. DNA was believed to be a tri-helix, by L. Pauling, but backed up crystalized x-ray structure Watson and Crick proposed their own idea of DNA being a double helix structure. Along with their proposed structure they further state that purine and pyrimidine bases hold the two chains together. These bases are joined together specifically in a way that adenine pair with thymine and likewise guanine with cytosine. They go on by explaining that one chain goes from 3’ to 5’ and the other is 5’ to 3’. With this knowledge of the sequence of one chain they state that it is possible to sequence the other. This model makes more sense and is more simplistic then the original tri-helix structure. If this theory holds true, it will truly bring forth larger break through in DNA engineering and more.

    • You mention how these base pairs are held together in a “specific” way. The bonds themselves are due to hydrogen bonding. The bonding between Adenine and Thymine causes two hydrogen bonds to form and between Guanine and Cytosine three hydrogen bonds are made. And they can only pair in such a way that specific purine matched up with its partner pyridine.

  13. From a theory of a triple helix to one of double raises some suspicion in my mind. Which one of these two theories proves to be true? A hypothesis theorized by two men who’s area of research is completely off from this topic. I must say their idea in comparison to Pauling and Corey’s idea Watson and Crick’s theory was interesting as they claim to achieve something that looks to be as complex as a quad helix be a double helix dismissing that it can be triple helix.
    DNA is accredited ( according to Watson and Crick’s second paper) to contain genetic material to replicate itself and yet it is being categorized as a double helix instead of a triple helix which would seem to any to be more logic.
    However their Watson and Crick’s theory of the bases and its paring makes complete sense. According to simple organic chemistry an enol is highly unstable and thus rearranges to give a keto which would make sense that the base pairing is arranged to suit this simple law of chemistry.
    With careful consideration and organization of Watson and Crick theory it seems that their idea is one which makes complete sense. However it does sparks one imagination to know how this discovery came to be taking into consideration their original goal of research.

    • I agree with you on questioning how the discovery came about. It seems like they just stole the “Spotlight” when this wasn’t even there field to begin with. I also agree that Watson and Crick’s model makes complete sense. It follows the rules of chemistry and is very logical. They should have added more data to support their claims so we wont be so questionable.

  14. This new idea proposed by J. Watson and F. Crick about the DNA structure is truly astonishing. However, after a closer examination of their manuscript I could not help but realize the lack of data. “We have assumed an angle of 36°…” “If it is assumed that the bases…” “…then on these assumptions…” Was this hypothesis of yours created from numerous experiments or is it all simply based on assumptions? Any mad-man can write a page about the DNA being a certain shape; even I could say it’s a Quintuple-stranded molecule, if I wished. Yet, I withdraw from making such preposterous remarks because I do not have the evidence to support it.

    So, what I am trying to say is, I will not accept this new idea solely on the fact that it lacks evidence. But, if J. Watson and F. Crick decide to shed more light on these uncertain areas, I will happily reconsider my standpoint after evaluating their data. I hope you all will be more cynical when it comes to reviewing new ideas and refrain from getting too excited.

    • I agree that Watson and Crick say a lot without any scientific proof for what they say. One paragraph in particular bothers me because it is short and makes claims without any scientific proof. It says, “This structure is an open one, and its water content is rather high. At lower water contents we should expect the bases to tilt so that the structure could become more compact.” What does that even mean? Maybe Watson and Crick were too excited and published little bits of everything they knew about DNA without giving too much away to other scientists.

  15. What a remarkable discovery from Watson and Crick! If true, this can be a huge breakthrough for the field of science. Their model describes DNA as a double-helix, where a single base of one chain is hydrogen bonded to a single base of the other chain. This model seems very conceivable. The double helix makes more sense compared to the triple helix model because of Chargaff’s base pairing rule. His rule states that A pairs with T and C pairs with G. Watson and Crick also points out that in the DNA strand, a purine (which are Adenine and Guanine) always binds with a pyrimidine (which are Thymine and Cytosine). If this holds true, this can give the DNA structure more stability because the width of the DNA will be constant. Also, Watson and Crick’s model is more chemically stable than the other models proposed. In Watson and Crick’s model, the base pairs are in the middle and the phosphate backbone surrounds it. If the phosphate backbone were on the inside like Pauling’s model states, the negative charges would repel each other. This is an amazing start on the discovery of DNA’s role and structure.

    However, while I was reading this paper, I realized that there was not enough experimental data. It seemed more like a research paper. Until more data is gathered and examined, we cannot fully prove that this model is the right model for DNA. Regardless of the lack of data, this is an amazing start on discovering DNA’s role and structure.

    • I find this post very similar to mine. The model they represented with the explanation of the base pairing bettered my knowledge and understanding of how the pairing works. The model presented had the backbone of phosphate that enables more sequences of the pairs to appear, which falls into their genetic research data. Amoungst Watson and Crick they were able to give a pretty solid explanation on the DNA model and soon I think someone will be bringing forth further answers to this major discovery. This is just one of the many discoveries to bring forth and better the scientific field’s unsolved questions/experiments.

  16. The DNA structure proposed by Watson and Crick seems to provide answers to the genetic code. The double helical structure is held together by the rules of base pairing with adenine binding to thymine and cytosine binding to pyrimidine. This may explain why the triple helix model is flawed. Whats interesting is that its been stated the base pairing sequence is unique with only one selection of pairing. They suggest base pairing sequence in DNA provides the answer for duplication; with one strand, you can recreate the other from the base pairing. The irregular base sequence issue that they address may be the causes of genetic defects, but this may be jumping to conclusions too quickly. The phosphate sugar backbone allows long varying sequences of base pairs to occur, providing a method of genetic diversity.

    The only issue that bothers me is that this is an idea, not something that Watson and Crick has proven, meaning there is room for error in their theory for DNA structure. Much of their idea on the structure calls back on previous proven knowledge. Even so, their proposal for the DNA structure is uncannily detailed, and their proposal may grant many answers to unresolved questions in DNA structure.

    • There tends to always be room to expand upon ideas presented.The base pairing sequence in DNA however, is not one of them since it brilliantly defines the double helix structure and the rules for duplication. As aforementioned the phosphate backbone also does indeed allow for not only structural support but, agreebly allows for genetic diversity.

      Although the discovery has been put together it has been accomplished through vast amount of work that was already available amongst the science community. The stepping stones to this proposal were already a laid foundation but, Watson and Crick undoubtedly put it together. This conception of DNA is now readily accepting amongst people as some skeptics still continue to question. In consensus, there is definitely always room for expansion.

  17. Watson and Crick’s discovery that DNA is an anti-parallel double helix is arguably one of the biggest discoveries in scientific history. Their discovery was the missing link to finding the answer to a question that had stumped scientists for years. Although Watson and Crick do not immediately explain how their finding solves this age-old mystery, they publish enough information so that the science world knows that the code has been cracked. This discovery meant more than just figuring out how DNA is built; Watson and Crick made a breakthrough in science that would advance genetic research as well as open new doors for research in areas of science that had yet to be explored.
    Watson and Crick knew their discovery was an important one, but they never could have imagined the magnitude of their findings or what movement they started. Watson and Crick opened Pandora’s box to scientific and medical advancement. In 1953, scientists were still learning about DNA, its structure, and its function. Today, scientists have gone so far as mapping the entire human genome. Doctors today can give the probability of a baby’s chance of being born with genetic diseases before the baby is even born. A single strand of hair is enough to incriminate or exonerate a suspect in a crime. Watson and Crick could have never imagined the scope or the significance of their discovery that is still the basis of discovery today.

  18. After reading the article proposed by Watson and Crick, I was at first skeptical. If their idea of DNA being a double helix was in fact true, this could be a breakthrough in science! After reading the article many times and trying to make sense of it, I am finally convinced that their proposal is in fact legitimate. The discussion of the Purines and Pyrimides is what swayed me. Watson and Crick explained with great detail exactly how the bases hold the 2 helical chains together. I found it fascinating that the single base from one pair is hydrogen bonded to the other single base, causing the base pairs to lie side by side. Also, a pyrimidine (cytosine and thymine) has to pair with a purine (adenine and guanine) in order for the bonding to occur. If the sequence of one chain is given, then the sequence of the other chain is automatically determined. According to their statistics, adenine will always pair with thymine, while cytosine pairs with guanine. Watson and Crick obviously put much time, research, and hard work into this model; I believe that this paper is a breakthrough in science, and will lead to many new ideas and discoveries!

    • I found this post affective because it gives an explanation as to why a strand of DNA is a double helix, using the examples of purines and pyrimidines. I agree with this information becuase I believe that it is solid evidence as well. Watson and Crick have science to support their ideas that each purine attaches to a pyrimidine. Even though this is a good example, I think Maximie should explain another reason as to why a double helix is the correct structure over the triple helix that was presented by other scientists. I think that she should explain another idea that could solidify why she thinks that the double helix is the correct structure.

  19. After the discovery that Watson and Crick had recently made about deoxyribonucleic acid (DNA) structure could change the way we view science forever. These two men came up with a structure that described DNA as being a double stranded helix. After reading the articles on how they arrived at their conclusion, I was convinced that the double helix is the correct structure for DNA. The DNA is composed of nucleotides that will code for the genes of each individual person. The nucleotides are separated into two categories: purines (adenine and guanine) and pyrimidines (cytosine and thymine). Each purine is paired with a pyrimidine on the complimenting DNA strand. It is proven that there are approximately the same number of adenine and thymine and the same number of cytosine and guanine on a single DNA strand. This shows that adenine with always pair with thymine and cytosine will always pair with guanine.
    Before they exposed their model of a double helix, Pauling and Corey, two scientists, proposed a triple helical structure. However, it was in turn rejected by Watson and Crick. The forces and hydrogen bonds holding the helix together would have been too small, and some of the forces would actually repel each other which would not allow for the helical shape. After reading the articles I am convinced that DNA is in fact a double-helix shape.

    • The discussion of DNA being composed of nucleotides is what convinced me that Watson and Cricks’s model was legitimate. The way the purines and pyrimidines pair with one another creating a double helix makes much more sense than Pauling and Corey’s model. Their idea of having a triple helix, with the phosphates near the axis and the bases on the outside makes no sense. Especially since, as you mentioned, the negatively charged phosphates near the axis are going to repel one another. Watson and Cricks proposal of having bases on the inside and phosphates on the outside makes much more sense.

  20. Within the article Watson and Crick seem to have made the major discovery of the DNA structure. Within their argument it seems very reasonable and almost has me convinced, it also kind of makes me question science in a way. Through their discovery they were able to explain and better my understanding as to how DNA is made pretty vividly. The double helix structure was in one situation described as being held by hydrogen bonds but in the Watson and Crick theory their base pairs were hand in hand and made much more sense; pyrimidine with cytosine and adenine with thymine. I want to further my knowledge on their research of the genetic research they have done, the fact that their discovery isn’t set in stone makes me question why anyone has not furthered this and perfected it enough to where it has enough legit information that other scientists could work off of and find more answers.

    • I agree with that this discovery is worth while and should be furthered studied so it can be perfected and aid in the study of genetics. I believe that with a little more research we will be able to determine wheter DNA is the genetic material of life.However, when you explaining about the base paring, it is cytosine that guanine, which is a purine not a pyrimidine.Hopefully other scientists do work off this model to better our understanding of DNA. I also agree with your statement that this idea idea is not set in stone so maybe with more research this theory may even fall apart.

  21. Not just an interesting and fascinating article, but also an article that persuades the reader to think beyond the scientific imagination. After looking at the model by Watson and Crick I was immediately taken away by the developed structure. The double helix structure made much sense after several hours of thought and review. From the phosphate back-bone structure on the outside, if I am correct, to the base pairs known as purines and pyrimidines. Having them held together by hydrogen bonds made absolute sense. If this structure holds true to be correct, Watson and Crick and surely begin to prepare for a Nobel Peace Prize. Their was a question that I had trouble trying to understand regarding the purines and pyrimidines. From the four pairs you established (Guanine, Thymine, Cytosine, Adenine) is possible that you guys may have missed out on other amino acid begin members of our DNA structure? Acids such as Methionine or Selenocysteine—common start and stop codons. Just a thought but further more, your prediction of DNA still looks very convincing and motivating for the discovery into human genetics.

    • There are no questions about the fact that this article “persuades the reader to think beyond the scientific imagination.” Their newly formulated double helix, instead of the previously presented triple helix model, is more convincing. As you have mentioned “DNA still looks very convincing and motivating for the discovery into human genetics,” having this idea o hold its ground will the lead for the break in the history of science.

  22. Watson and Crick’s theory about the structure for deoxyribose nucleic acid (DNA) is simply fascinating! They have changed our view of DNA being a triplex helix as originally proposed by Pauling and Corey to it being an anti-parallel double helix. Their reasoning behind this structure does make a lot of sense though. According to their theory DNA is made of a two anti-parallel chains that are made of a phosphate-sugar backbone, which are one the outside and the nucleotide base pairs on the middle. The reason this model makes sense is because if the phosphate backbone were on the inside the negatives charges would repel each other. Also, it is the hydrogen bonding between the base pairs that keep the DNA intact. There are four nucleotide bases adenine, guanine, thymine, and cytosine. They can be separated into two categories: purines (adenine and guanine) and pyrimidines (cytosine and thymine). Adenine always pairs with thymine and cytosine always pairs with guanine because one of the pair must be a purine and the other must a pyrimidine in order for bonding to occur. Watson and Crick have done a great job in deciphering the structure of DNA from the X ray data obtained from M. Wilkins and R. Franklin.
    However, despite the sound chemistry behind Watson and Crick’s theory there is not a lot of evidence or data to support their claims. For example, on thing I would like a further explanation on why purines and pyrimidines must pair together. It is only briefly mentioned that of a pair consisted of two purines there would not be enough for it between the backbone. Another, claim that I had trouble understanding is the reason why it would be impossible to build a structure like DNA with a ribose sugar in the place of deoxyribose. It is stated that the extra hydrogen atom would make too close a van der Waals contact, but no evidence is given to support this. Despite the lack of evidence of given by Watson and Crick for their double helix theory of DNA I still believe that the model is a solid one that can only be improved with further research.

  23. What a major difference between the L. Pauling’s theory and Watson and Crick’s theory. The two theories took a big jump; DNA was thought to be in the form of a triple helix, however Watson and Crick have deduced that DNA is in the form of a double helix. Although they do not have any solid proof of this, they have a sufficient amount of evidence for people to believe such an assumption.
    Their model has a better foundation than that of Pauling and Corey. They state that DNA is an anti parallel double helix that are held together by a phosphate sugar backbone. This would make sense as to keeping the DNA stable. They also include their theory of the base pairs. There are purines and pyrimidines; and a purine must bind with a pyrimidine. Although they do not explain and go into detail as to why these purine bases must pair with a pyrimidine base. Providing an explanation for this base pairing would be more effective and answer some questions.
    Based off all their research, this model is one that can change the future.

    • It seems that now when comparing the two models, the double helix looks more appropriate. This idea may end up revolutionizing our understanding of DNA if proven true. I must agree that Watson and Crick must have spent much time creating a very detailed model of the DNA structure with good reasoning. When pieced together, all the ideas that they put together for the structure seem to make perfect sense. The explanation behind the purine-pyrimidine pairing was stated that only this pairing would fit in the double helix model, but it does make one wonder how Watson and Crick put this much thought into the space within the DNA.

  24. The discovery of the structure of DNA will change the way we view human genomics forever. At first, I was wary to read another article about the structure of DNA, but after reading Watson and Crick’s article I am convinced. After several hours of examining the structure, the double helix was the only logical structure. Many of the other structures agree on the fact that they have a phosphate sugar backbone and the presence of purines and pyrimidines, but they do not explain the hydrogen bonds and base pairings that are involved. If this structure is correct, Watson and Crick will be synonymous with human genomics.

  25. New discovery proposed by Watson and Crick sounds to be convincing. This discovery can change everything that we already know. This impact is revolutionary and has a strong potential to improve research in the near future and open doors for more new discoveries. It never crossed my mind that the structure of DNA is a double helix that has two helical chains each coiled around the same axis. As they point out, along with convincing evidence, the double bonded strand of the DNA sounds more reasonable than a triple helix-pairing strand. An example that they provide us is that if adenine pairs with thymine, then guanine and cytosine pair together respectfully. Their vivid representation that the DNA strand, having bases joined in pairs, represents the structure of our life and is the key for new discoveries that will change our perspective on life for once and for all. Studies in Genetics are on a rise and this could be a lead for breaking the ice in history. It might give us those crucial answers for questions we were asking to have.

  26. Life has always been a puzzle. How do we come out the way we do?
    It is a piece to a puzzle and an extraordinary discovery. Watson and Crick came up with an amazing theory with amazing ideas. How did they come to this discovery and what is there to support it?
    These ideas, double helix and DNA replication are far fetch. The DNA replication explains how our bodies come to be and grown as we get older. How are you so sure that there are only four bases but the different sequences of the bases seem to explain how everyone looks different, yet alike. With only four base pairs in countless order explains how some share similar genetic codes then others.
    This is only the beginning to an amazing start, a new view on the way we look at human beings and a new start for science.

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