Using Feedback to Control Weight
Recent research has shown that exhaust from lungs (part of excretion) is a major factor in weight loss. Burning 10 kg human fat requires inhalation of 29 kg oxygen. This produces 28 kg carbon dioxide and 11 kg water. As food and drinks are temporarily stored in the human stomach and bowels, the body weight is instantaneously increased with the weight of any food or drink consumed. Metabolism is usually divided into catabolism and anabolism, where catabolism is the process of breaking down ...Computer Metaphors for Biochemistry
The metaphor of the computer represents in some crude fashion the chemistry of life. Nowadays one may assume that the average citizen of an industrialized country is at least as familiar with computers as with rain forests. The idea of using the computer as a metaphor is a natural one. A computer is a device for handling information according to a program which it is able to remember and execute. A living cell, to remain in control of its vital functions in a variable environment, must also p...The Signaling Pathway
In a typical signaling pathway, proteins are continually being modified and demodified. Kinases and phosphatases work ceaselessly like ants in a nest, adding phosphate groups to proteins and removing them again. It seems a pointless exercise, especially when you consider that each cycle of addition and removal costs the cell one molecule of ATP—one unit of precious energy. Indeed, cyclic reactions of this kind were initially labeled “futile.” But the adjective is misleading. The additio...The underlying cyclical process of a synapse firing that turns it into a "tunable" device.
If a Scientist Wrote the Book of Genesis
In the beginning was the singularity, and the singularity was infinitely dense and infinitely hot, And the singularity expanded and the singularity cooled and there was chaos, And of the primeval atom was born the Universe. And the Universe was matter and antimatter, and baryogenesis was violated and matter annihilated antimatter until only matter remained, And matter resolved into hydrogen, and after hydrogen came helium and deuterium and all elements, And with elements came mass and with ma...Opening chapter of genesis written in science.
Organic Chemists Merely Increase the Probability of Results
It is, I believe, justifiable to make the generalization that anything an organic chemist can synthesize can be made without him. All he does is increase the probability that given reactions will 'go.' So it is quite reasonable to assume that given sufficient time and proper conditions, nucleotides, amino acids, proteins, and nucleic acids will arise by reactions that, though less probable, are as inevitable as those by which the organic chemist fulfills his predictions. So why not self-dupli...In nature, with enough time and proper conditions, the results would happen eventually without him, including self-duplicating molecular systems like viruses.
The Molecular Beauty of a Butterfly
When I see the butterfly, I imagine in my mind's eye the extraordinary chemical machinery of life, the winding loom of he DNA, the proteins linking like lock and key, the ceaseless hubbub of molecular commerce that goes on behind the scenes, from egg, to caterpillar, to chrysalis, to adult. Surely, no land of faerie is more magical than the transformation that occurs in the chrysalis, when a creepy-crawly caterpillar curls up in a self-made sack and rearranges its molecules to emerge as a win...Chet Raymo describes what he sees when he thinks of a butterfly.
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.
Extended Families as Important as Minerals and Proteins
Yes, and Trout harped on the human need for extended families, and I still do, because it is so obvious that we, because we are human, need them as much as we need proteins and carbohydrates and fats and vitamins and essential minerals.Yes, and Trout harped on the human need for extended families, and I still do, because it is so obvious that we, because we are human, need them as much as we need proteins and carbohydrates and fats and vitamins and essential minerals.
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.