122 Information Storage and Neural Control 



and transcribing in the same letters, but perhaps smaller, the 

 information which is in the DNA. Whether this is done by three 

 bases together in the DNA, or whether the number is twenty is 

 not at the moment important as long as we get the general effect 

 across. 



Kit: The problem that faces us is this: Proteins vary greatly 

 in their length; they can be very short or they can be very long. 

 How could we obtain proteins of various sizes if the messenger- 

 RNA's were all of uniform sizes? I was deliberately ambiguous 

 on this point in the diagram because we do not really know how 

 many proteins are coded by one DNA molecule. There might 

 be several. In other words, we do not know where the periods 

 and where the commas are on the DNA chain. 



Mayor: I am interested to see that the minimal infective 

 amount of DNA in the animal viruses appears to be around 

 4 X 10*^, whereas, the molecular weight of DNA, for instance, in 

 T-2 phage is about 120 x 10^ Would this be because more in- 

 formation is necessarily contained in the DNA of phage in com- 

 parison with the animal viruses, or would this be a problem in 

 redundancy again? Do you think that there must be more infor- 

 mation contained in the DNA of T-2 than in rabbit papilloma 

 SV-40, or any of the animal viruses? 



Kit: I think it is quite likely that there is more information in 

 vaccinia or T-2 phage than in ^X174 polio or Shope papilloma 

 virus. The minimum information that must be present in a virus 

 is the information necessary to specify the protein coat of the 

 virus. For tobacco mosaic virus this would have to be enough 

 information to specify a protein having a molecular weight of 

 17,500. This would require about 900 nucleotides on the basis 

 of a triplet code, x^ctually, there are about 6,000 nucleotides in 

 a TMV-RNA chain. Thus, it is very likely that there is additional 

 information even in tobacco mosaic virus, or in other small 

 viruses. I think that Dr. Darnell will elaborate on this point in 

 connection with the genetic information brought in by T-2 phage 

 DNA for specific protein synthesis. 



