17 MAR 2012 by ideonexus
The Sequence Hypothesis and The Central Dogma
My own thinking (and that of many of my colleagues) is based on two general principles, which I shall call the Sequence Hypothesis and the Central Dogma. The direct evidence for both of them is negligible, but I have found them to be of great help in getting to grips with these very complex problems. I present them here in the hope that others can make similar use of them. Their speculative nature is emphasized by their names. It is an instructive exercise to attempt to build a useful theory ...Crick describes two guiding principles of understanding how DNA produces proteins. The second is interesting for the use of the term 'information.'
21 SEP 2011 by ideonexus
1.5 Percent Gene Difference Translates to Thousands of Pr...
But recent work shows that our genetic resemblance to our evolutionary cousins is not quite as close as we thought. Consider this. A 1.5 percent difference in protein sequence means that when we line up the same protein (say, hemoglobin) of humans and chimps, on average we’ll see a difference at just one out of every 100 amino acids. But proteins are typically composed of several hundred amino acids. So a 1.5 percent difference in a protein 300 amino acids long translates into about four di...The analogy is made that if you change 1 percent of the words you change much more than 1 percent of the sentences, and the same applies to the genetic drift between humans and chimps.
09 JUN 2011 by ideonexus
The Uselessness of Nitrogen in the Atmosphere
My 165-pound body consists of about 110 pounds of oxygen, 30 pounds of carbon, 16 pounds of hydrogen, 6 pounds of nitrogen, and 3 pounds of everything else. Basic stuff, mostly, the stuff of water and air. You'd think we could get almost everything we need to build our bodies by taking deep breaths and gulps of water. But it's not quite that simple. Consider those 6 pounds of nitrogen in my body. Our cells build proteins by stringing together chemical units called amino acids, and every amino...Raymo describes how many pounds of each element there are in his body, and why, despite them mostly all existing in the air we breath, they are bound up in molecules so that we cannot access them.