Genome complexity: 'speed' code (Introduction)

by David Turell , Wednesday, September 23, 2015, 20:06 (3349 days ago) @ David Turell

The speed with which a protein is made depends on which codon is used. Some cause more speed, some cause less speed of manufacture, and this speed controls folding to create function.-http://www.sciencedaily.com/releases/2015/09/150923134211.htm-"It was long known that almost every amino acid can be encoded by multiple synonymous codons and that every organism, from humans to fungi, has a preference for certain codons. The researchers found that more frequently used codons ? the "preferred codons" ? speed up the process of producing an amino acid chain, while less frequently produced codons slow the process. The use of either preferred or non-preferred codons is like having speed signs on the protein production highway: some segments need to be made fast and others slow.-"'The genetic code of nucleic acids is central to life, as it specifies the amino acid sequences of proteins," said Dr. Liu, the Louise W. Kahn Scholar in Biomedical Research. "By influencing the speed with which a protein is assembled from amino acid building blocks, the use of "fast" and "slow" codons can affect protein folding, which is the process that allows a protein to form the right shape to perform a specific function. This speed control mechanism makes sure that proteins are assembled and folded properly in different cells. Therefore, the genetic code not only specifies the sequence of amino acids but also the shape of the protein."-"The researchers found that proteins with identical amino acid sequences can have different functions if they are assembled at different speeds. This can have important implications for identifying human disease-causing mutations because this study indicates that a mutation does not have to change amino acid identity to cause a disease. In fact, most mutations in human DNA do not result in amino acid change.-"'Therefore, our study indicates that the new "code" -- the speed limit of assembly -- within the genetic code can dictate the ultimate function of a given protein," said Dr. Liu."-Comment: science is finding the genome more and more complex. With increasing complexity the likelihood of Darwinian chance evolution lessens to zero.