Why genetic information processing could have a quantum basis

Abstract

Living organisms are not just random collections of organic molecules. There is continuous information processing going on in the apparent bouncing around of molecules of life. Optimisation criteria in this information processing can be searched for using the laws of physics. Quantum dynamics can explain why living organisms have 4 nucleotide bases and 20 amino acids, as optimal solutions of the molecular assembly process. Experiments should be able to tell whether evolution indeed took advantage of quantum dynamics or not. Keywords.Amino acid; computation; database search; DNA; enzyme; information; nucleotide base; protein; quantum coherence; quantum mechanics; superposition; unitary evolution InformationWhat is life? About fifty years ago, Erwin Schrödinger attempted to answer this question on the basis of known laws of physics (Schrödinger 1944). His insight has since then inspired many researchers to investigate the molecular basis of a living organism. Chemical bonds explain how atoms bind together to form various molecules. It is possible to take the common elements H, C, N , O, stir them together with some heat and electric sparks, and obtain molecules of life such as water, methane, ammonia, sugars, amino acids, nucleotide bases, and so on. These molecules exist even in the interstellar clouds. It is also not difficult to arrange these molecules in an orderly manner as in a crystal, or jumble them up in a random ensemble as in a gas. But living organisms are neither ordered crystals nor random mixtures of their building blocks. The building blocks of a living organism are linked together in a precise fashion to make functional parts. These links between building blocks are often indirect and not physical; they describe an order amongst the building blocks. Information is the abstract mathematical concept that quantifies the notion of this order amongst the building blocks, and it was this concept that was emphasised by Schrödinger in his seminal work.It is easiest to quantify information using the framework of communication. When a message is conveyed by one person to another, the measure of the information contained in the message is the increase in the knowledge of the second person upon receiving the message from the first. The larger the number of possibilities for a message, more is the amount of uncertainty removed upon its receipt, and so more is the information contained in it. The simplest message would be just a yes or no, distinguishing amongst only two possibilities. Claude Shannon thus defined the information contained in a message as its entropy; it directly measures the number of possibilities for the message. A repetitious message wastes resources repeating what is already conveyed before. So the information contained in a message is increased by removing correlations amongst its parts; as messages become more efficient, they appear more and more random.Information thus lives in randomness, but it is not randomness. What distinguishes it from randomness is the sense of purpose, i.e. the m...

Biological complexity, quantum coherent states and the problem of efficient transmission of information inside a cell

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The triplet genetic code had a doublet predecessor

“…Its predictions match the number of building blocks involved in genetic languages (i.e. N = 4, 10, 20 for Q = 1, 2, 3 respectively (Patel, 2001)), when a query is identified with nucleotide base-pairing; no other purposeful explanation of these numbers is known. Explicitly, DNA/RNA have an alphabet of 4 nucleotide bases identified with 1 base pairing, polypeptides have an alphabet of 20 amino acids identified by 3 base pairings, and a single class of 10 amino acids can be identified by 2 base pairings.…”

Evolution of Cancer: A Quantum Mechanical Approach

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