- Molecular biologists are beginning to unravel the information processing tools-such as enzymes, copying tools, and so on-that evolution has spent billions of years refining. Now we are taking those tools in large numbers of DNA molecules and using them as biological computer processors.
· A single gram of dried DNA, about the size of a half-inch sugar cube, can hold as much information as a trillion compact discs.
· Each nucleotide-A, C, T, or G – can be considered a letter in a four-letter alphabet that is used to write our biological messages in a linear “ticker-tape” form.
· Organisms differ because their respective DNA molecules carry different nucleotide sequences and therefore different biological message.
· Since the number of possible sequences in a DNA molecule, which is n nucleotides long, is 4ⁿ, the biological variety that could in principle be generated using even a modest length of DNA is enormous.
· A typical animal cell contains a meter of DNA (3*10⁹ Nucleotides). Written in a linear alphabet of four letters, an unusually small human gene would occupy a quarter of a page of text, while the genetic information carried in a human cell would fill a book of more than 500,000 pages.