Uncommon Descent Serving The Intelligent Design Community

Histone Variants: The Incredible Story of Gene Regulation

Proteins are constructed from a string of amino acids, and the amino acid sequence is coded in a gene. But how does the cell know which of its many genes to use in synthesizing proteins? Gene regulation is accomplished via a number of complex mechanisms. For instance, methyl groups are used to tag both the DNA as well as the histone proteins about which the DNA is wrapped. You can read more about histones here and here. In addition to such methylation, histones can also vary by tiny differences in their amino acid sequence. Such histone variants serve as yet another type of tag used for gene regulation. Now new research is revealing the profound complexity of this mechanism.  Read more
semi-off topic: Maxwell’s Demon Helps Run Your Muscles - April 2010 Excerpt: James Clerk Maxwell once speculated that the second law of thermodynamics could be violated if an agent or “demon” could sort the hot and cold molecules at a barrier, thus overcoming the tendency toward thermal equilibrium. Something like this has been found at work in the molecular machines in our muscles. The actin-myosin motor is able to convert the random thermal motion (Brownian motion) of its environment into unidirectional motion due to the structural arrangement of its protein parts.,,, Myosin is like a robot walker on an actin racetrack. The robot uses ATP for energy. Each stepwise cycle requires ATP hydrolysis, but there is more energy in the action than can be accounted for by the ATP alone. The researchers determined that, as has long been suspected, the structure of the motor allows random thermal motion to be captured as with a ratchet. This “Brownian ratchet” mechanism helps propel the motor down the track in what they call a “functional funnel” of the energy landscape. “Our study embodies these theoretical models, indicating that a Brownian ratchet mechanism is likely to contribute substantially to the energy conversion of the actomyosin motor,” they said. http://www.creationsafaris.com/crev201004.htm#20100419a bornagain77
Of related interest: Scientists Discover New Genetic Sub-Code Excerpt: The researchers from ETH and SIB now identified a new sub-code that determines at which rate given products must be made by the cell. This information has several interesting implications. First, it provides novel insights into how the decoding machinery works. Secondly, and more pragmatically, it makes possible to read information about gene expression rates directly from genomic sequences, whereas up to now, this information could only be obtained through laborious and expensive experimental approaches, such as microarrays. "A cell must respond very quickly to injuries such as DNA damage and to potent poisons such as arsenic. The new sub-code enables us to know which genes are turned-on quickly after these insults and which are best expressed slowly. One benefit of this study is that we now can get this information using only analysis of the coding sequence," said Dr. Gina Cannarozzi. Additionally, the new sub-code provides insight into cellular processes at the molecular level. In every living cell, the translation allowing the production of proteins takes place at specialised factories, the ribosomes. The discovery of this novel sub-code will therefore also provide more information about the functioning of these ribosomes. Indeed, all the data gathered up to now indicate that these factories recycle their own components, the tRNAs, to optimize the speed of protein synthesis. This discovery of a new way to regulate translation could potentially be exploited to more efficiently produce therapeutic agents and research reagents. http://www.sciencedaily.com/releases/2010/04/100416144542.htm bornagain77
Dr. Hunter; here is a video that somewhat goes with your article: DNA - The Genetic Code - Error Minimization & Parallel Codes - Dr. Fazale Rana - video http://www.metacafe.com/watch/4491422 bornagain77

Leave a Reply