Before we look at their article, think about what you know about the structure of DNA. Then as you read the article, notice how the beginnings and endings of the paragraphs are almost like an abstract. These sentences summarize what most scientists know about the structure of DNA, plus some details that are of basic importance to geneticists, cell biologists, biochemists, and others in similar fields. This is how you should write your articles: the beginnings (and sometimes the endings) of paragraphs should be almost like an abstract of your work.
In the article, I have put an ellipsis, "…", where I have deleted sentences. The original citations have been deleted to make the article easier to read. The numbers in curly brackets, "{}", refer to my comments, which are written after the article.
A Structure For Deoxyribose Nucleic Acid
(Watson and Crick, 1953)
We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest.
A structure for nucleic acid has already been proposed by Pauling and Corey…
Another three-chain structure has also been suggested by Fraser…
We wish to put forward a radically different structure for the salt of deoxyribose nucleic acid. This structure has two helical chains each coiled round the same axis (see diagram)… {1}
The structure is an open one, and its water content is rather high…
The novel feature of the structure is the manner in which the two chains are held together by the purine and pyrimidine bases…
If it is assumed that the bases only occur in the structure in the most plausible tautomeric form (that is, with the keto rather than the enol configurations) it is found that only specific pairs of bases can bond together…
In other words, if an adenine forms one member of a pair, on either chain, then on these assumptions the other member must be thymine; similarly for guanine and cytosine…However, if only specific pairs of bases can be formed, it follows that if the sequence of bases on one chain is given, then the sequence on the other chain is automatically determined.
It has been found experimentally that the ratio of the amounts of adenine to thymine, and the ratio of guanine to cytosine, are always very close to unity for deoxyribose nucleic acid. {2}
It is probably impossible to build this sugar with a ribose sugar in place of the deoxyribose, as the extra oxygen atom would make too close a van der Waals contact.
The previously published X-ray data on deoxyribose nucleic acid are insufficient for a rigorous test of our structure. So far as we can tell, it is roughly compatible with the experimental data, but it must be regarded as unproved until it has been checked against more exact results… {3}
It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material. {4}
… {5}
NOTES:
1 – After an introductory sentence, we read the most important information. This is the one thing about the structure of DNA that even most non-scientists know: it is usually found in the form of a double helix.
2 – This paragraph and the following one are one-sentence paragraphs. Some students have wondered if this is considered correct English-language style. The answer is that it is unusual, but it can be done in good English-language writing. Watson and Crick may have done it because this is a short communication, and they were just presenting the most important information about their structure for DNA.
3 – Again, an introductory sentence leads to the main point of the paragraph.
4 – This concluding sentence is rather famous. Although native-speakers of English have often understood this as a slightly humorous attempt to look modest, non-native speakers are sometimes a little confused by it. The sentence seems much less clear than the rest of Watson and Crick's writing. Crick (1974) later explained that this sentence was a compromise between the authors: "Watson was against [suggesting that this structure for DNA explains how a copy of the genetic information can be made]. He suffered from period fears that the structure might be wrong…I…insisted that something be put in the paper, otherwise someone else would certainly write to make the suggestion…"
5 – Two paragraphs have been deleted here. They contained information about where full details of the structure would be published and acknowledgements.
EXERCISES:
1 – Look at your own writing, or ask a colleague to read it. Can you read only the beginning sentences of each paragraph, and sometimes the ending, and understand the main ideas of the article? If not, you need to reorganize your paragraphs.
2 – Read an article by a native-speaker of English that seems to be clearly written. Find the sentences that contain the main ideas of the paragraphs. Are they at the beginning, and sometimes at the end, of the paragraphs? If not, can you rewrite the paragraphs to make them better organized?
Please write any questions or comments below. If you find an article that seems to be very clearly written, please put a reference to it in the comments.
COMING SOON:
We'll look at individual paragraphs in some more modern articles that use the typical Introducion, Material and Methods, Results and Discussion structure. There will also be more exercises.
REFERENCES:
Crick, F. The double helix: a personal view. Nature 248, 766-769 (1974).
Watson JD, Crick FHC. A structure for deoxyribose nucleic acid. Nature 171, 737-738 (1953).
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