Information codes

The protein folding problem is the task of understanding and predicting how the information coded in the amino acid sequence of proteins at the time of their formation translates into the 3-dimensional structure of the biologically active protein. A thorough recent survey of the problems involved from a mathematical point of view is given by Neumaier [22]. 

In the 1950s, biologists (notably Francis Crick and James Watson) discovered the molecular basis for information coding in DNA and established that the workings of cells were molecular machines tvith understandable structure and function. Mathematician John von Neuman developed a mathematical theory of self-reproducing machines based on the biological theories. 

The nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are the chemical carriers of a cell s genetic information. Coded in a cell s DNA is the information that determines the nature of the cell, controls the cell s growth and division, and directs biosynthesis of the enzymes and other proteins required for cellular functions. 

The discovery of the base-paired, double-helical structure of deoxyribonucleic acid (DNA) provides the theoretic framework for determining how the information coded into DNA sequences is replicated and how these sequences direct the synthesis of ribonucleic acid (RNA) and proteins. Already clinical medicine has taken advantage of many of these discoveries, and the future promises much more. For example, the biochemistry of the nucleic acids is central to an understanding of virus-induced diseases, the immune re-sponse, the mechanism of action of drugs and antibiotics, and the spectrum of inherited diseases. 

DNA has two broad functions replication and expression. First, DNA must be able to replicate itself so that the information coded into its primary structure is transmitted faithfully to progeny cells. Second, this information must be expressed in some useful way. The method for this expression is through RNA intermediaries, which in turn act as templates for the synthesis of every protein in the body. The relationships of DNA to RNA and to protein are often expressed in a graphic syllogism called the central dogma. The concept was proposed by Crick in 1958 and was revised in 1970 to accommodate the discovery of the RNA-dependent DNA polymerase. Crick s original theory suggested that the flow of information was always from RNA to protein and could not be reversed, yet it allowed for the possibility of DNA synthesis from RNA. 

Gene expression Entire process that translates the information coded in a gene into RNA and proteins. Expressed genes are transcribed into mRNA and subsequently translated into protein or they remain as RNA (e.g., transfer and ribosomal RNAs). 

Albert K., Walt D. R., Information coding in artificial olfaction multisensor arrays, Anal. Chem. 2003 4161-7. 

Taste receptor cells are organized into taste buds 825 Sensory afferents within three cranial nerves innervate the taste buds 826 Information coding of taste is not strictly according to a labeled line 826 Taste cells have multiple types of ion channels 826 Salts and acids are transduced by direct interaction with ion channels 826 Taste cells contain receptors, G proteins and second-messenger-effector enzymes 827... 

Ressler, K. ]., Sullivan, S. L. and Buck, L. B. Information coding in the olfactory system evidence for a stereotyped and highly organized epitope map in the olfactory bulb. Cell 79 1245-1255,1994. 

In the sections that follow, we are going to describe a few representative examples of how histone variability (histone variants and their post-translational modifications) can affect nucleosome stability and folding. This data supports the notion that while some of this variability may be exclusively used to provide an informational code [121,123,165] it can also have important implications for structural aspects involved in the highly dynamic nature of the chromatin fiber. 

Dominance status information, coded in whole-body odor, can travel between animals in an air stream. When exposed to the odor of a familiar, dominant male, the sugar glider, P. breviceps, increases cardiac and respiration rates within 10 minutes, and levels of glucose and catecholamine in the plasma rise after 30 minutes (Stoddart and Bradley, 1991). 

Buck, L. (1996). Information coding in the vertebrate olfactoiy system. Annual Review of Neuroscience 19,517-544. 

Information coding in the olfactory system evidence for a stereotyped and highly organized epitope map in the olfactory bulb. Cell 79 1245-1255. 

Interferon-a2 concentrated solution is a solution of a protein that is produced according to the information coded by the o2 sub-species of interferon-a gene and that exerts non-specific antiviral activity, at least in homologous cells, through cellular metabolic processes involving synthesis of both ribonucleic acid and protein. Interferon-a2 concentrated solution also exerts antiproliferative activity. Different types of interferon a2, varying in the amino acid residue at position 23, are designated by a letter in lower case. 

Intrinsic X-Ray Absorption. The maximum amount of information coded in a radiologic image is limited, in part, by the statistical fluctuations of the x-ray photons that form the radiologic image (I). These fluctuations are often referred to as "quantum nois e and as "quantum mottle" when viewed on films since the films have a grainy appearance (I7 ). These fluctuations can be expressed as a signal to noise ratios (1. ... 

RNA polymerase is a huge enzyme with many parts, including a dozen different proteins. Together, the different parts form a factory that surrounds the DNA strands, unwinds them, and, using the information coded in the DNA chains, builds an RNA molecule. Once the enzyme gets started, it zips along the DNA, creating... 

Buck L. B. (1996) Information coding in the vertebrate olfactory system. Annu. Rev. Neurosci. 19, 517-544. 

An answer to this apparent riddle is provided by RNA. Ribonucleic acid is actually a DNA equivalent, since it can store and replicate genetic information. Importantly, it is also a protein equivalent, since it can catalyze critical chemical reactions. Indeed, the first life-forms were probably entirely RNA based, and RNA has remained part of our cellular systems (Watson, 2004). Thus, RNA translates the genetic information coded for in our DNA into information that proteins can understand and act upon and does so in a remarkable manner. 

All the information coding for every protein in an organism is contained in its DNA in units called genes. The DNA content of almost every cell in a multicellular organism is the same and contains all the information needed to create the entire organism. 

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