Did that 50MB figure derive from just the protein-coding part of the genome? I just tried out the sequence from http://hgdownload.cse.ucsc.edu/downloads.html#hu

Did that 50MB figure derive from just the protein-coding part of the genome? I just tried out the sequence from http://hgdownload.cse.ucsc.edu/downloads.html#human http://hgdownload.cse.ucsc.edu/downloads.html#human. After converting it to binary, 2 bits per base pair, bzip2 compresses it down to about 650MB (from 715MB uncompressed). I'd like to know what assumptions give you an order of magnitude greater compression, and how probable they are. I suppose the biggest factor has got to be junk DNA, since species can vary so much in genome length -- but I get the impression there's a lot of uncertainty still about functional noncoding DNA. (The other number estimated was how many lines of source code the compressed 50MB or 25MB might correspond to. In the last thread I couldn't get this number to work either, though it came closer; and I actually know something about programs.)