The Cell's Design--part 3

The next section of Dr. Fuzale Rana’s book, The Cell's Design, covers biochemical fine-tuning which conveys a sense of the remarkable exactness of biochemical systems. Aquaporins form channels in cell membranes where they transport water across the membrane. Amino acids have to be brought into an exact alignment to form a useful three-dimensional architecture. In addition, collagens, the most abundant proteins in the animal kingdom, also contained an exact, fine-tuned amino acid composition.

Exact fine-tuning is not limited to the structure of the biomolecules. The rate of chemical processes is also carefully refined. For example, the cell's machinery copies mRNA from DNA only when the cell needs the protein encoded by a particular gene housed in the DNA. When that protein is not needed, the cell shuts down production. Biochemists have also discovered that the breakdown of mRNA molecules is not random but precisely orchestrated. Proteins are constantly made and destroyed by the cell. Those that take part in highly specialized activities within the cell are manufactured with great timing -- only when they are needed. Once the proteins are no longer useful, the cell breaks them down into the amino acids of which they are made up. This also is an exacting, delicately balanced process.

Rana then spends some time on the precise arrangement of elements in the cell. Amino acids link together in a head-to-tale fashion to form chains of proteins. These sequences appear to be highly optimal. Their exact positioning makes proteins better able to withstand mutations to DNA that result in a change to the amino acid sequence. Their structures also appear perfect to withstand damage caused by oxygen in the cell. The molecules that make up the backbone of DNA and RNA appear to be in a highly specific arrangement. Their chemical properties produce a stable helical structure capable of storing the information needed for the cell’s operation.

The Cell’s Design continues by highlighting the information found in the cell. Proteins and DNA are information-rich molecules. Just as letters form words in our language, amino acids are strung together to produce useful information. The chief function of DNA is to store information; it houses the directions necessary to make change-like molecules (polypeptides). DNA compares to the reference section of the library where books can be read but not removed. The material stored in these books has to be copied before it can be taken from the library -- exactly the same thing happens in the cell. The language of DNA and RNA is translated at the ribosome into the amino acid language of proteins. DNA can store an enormous amount of information -- theoretically one gram of DNA can house as much information as nearly one trillion CDs. To summarize, it's not the mere presence of information that argues for a designer. It's the structure of the information housed in proteins and DNA. There is a direct analogy between the architecture of human language and the makeup of biochemical systems. This information is handled exactly like a computer would do. For example, computer scientist Leonard Adleman recognized that the proteins responsible for DNA replication, repair, and transcription operated as Turing machines, which gave rise at a fundamental level for all computer operations. I don't have the space here to develop this, but check pages 163-168 in Rana’s book.

I need a couple more blogs to finish reporting on Rana's book. The detail in it blew me away with its careful analysis of the cell's abilities. Hope you feel the same.