"The molecular structure of the gene"

Date:: [1953]

Reference:: PP/CRI/H/1/12/3

Credit: "The molecular structure of the gene". Source: Wellcome Collection.

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$£W1 Uíuv/U! fTkfwJ I fro—eey^â resist attempts to coil it around its neighbours^*a¡ w h ^ h H rrht gniliiinm ' Ì ■■ ill;* î!i '1 l,if m HI 1nr7 We should point out, moreover, that even momentarily forgetting the necessity for uncoiling, simple geometrical consider- ?<rr*u- ftf-v* ft ations make regular super folding process imperative. fsM the¿length of the - For instance, DNA within T2 is 8.5 x 10 5 A« As its DNA is thought (Siegal and Singer, 1953) to have approximately the same very large M.W» as that from other sources, it must bend hack and forth many times in order to fit into the phage head of diameter 800 A. When we further consider that a single u*»\ of % dimensions 10^ x 10^ x 2 x 10^ A can produce about 500 phage particles within 30 minutes, the necessity for véby regular super folding becomes even more manifest« $U \ The second main objection to our replication scheme is that our structure does not différenciate between cytosine and 5 methyl cytosine and so that during replication the specificity in sequence involving these bases would not be perpetuated. We should point out, however, that in view of the erratic appearance of 5 methyl cytosine, it is possible that the difference between the two cytosines is not functionally significant. The fact that the sum of the two cytosines tends to equal the amount of guanine (Wyatt 1952) is strong evidence for our pairing scheme. This viewpoint is further supported by the discovery of Wyatt and Cohon (1953) that amount of the 5 methyl-hydroxy-cytosine ( a newly found pyrimidine base which completely replaces cytosine in the T even phages) tends to equal the amount of guanine.$

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"The molecular structure of the gene"

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