The Beauty and Fascination of Science by Anatoly L. Buchachenko

Author:Anatoly L. Buchachenko
Language: eng
Format: epub
ISBN: 9789811525926
Publisher: Springer Singapore

Genetics: Man as a Treasure of Relics

“View of the world through the window of the genome”—so the brilliant Russian scientist-geneticist Sverdlov called his book on genetics. This is a window into the inner world of life, the world that is charmingly beautiful, delightfully harmonious, and wisely arranged. It is based on one molecule—deoxyribonucleic acid (DNA). The molecule is simple and chemically even primitive: it is composed of four nucleotides connected in a polymeric polynucleotide chain by phosphate bridges. A nucleotide is a phosphate group joined to a nucleoside. A nucleotide is a nucleic base linked to a sugar molecule—ribose. DNA has four bases: adenine (A), cytosine (C), guanine (G), and thymine (T). The polynucleotide chain as a sequence of nucleotides is denoted by these letters: AGCTGA, etc. The two chains are combined, weaving into the correct double helix. The DNA molecule is usually understood as a magic double helix, the icon of the biology of the twentieth century. The total length of DNA molecules in the cell reaches 1–2 m, but they are folded on histone proteins, reducing the size of millions of times. All this information is the forgotten information from the school textbook. However, education is what remains after all that has been learned is forgotten…

DNA is a smart molecule, self-replicating one… The process of its reproduction is called replication. The smart enzyme—helicase—moves along the DNA molecule and unravels the spiral. It is followed by even more intelligent enzyme—DNA polymerase, which uses the old DNA chains to build new DNA threads, attaching the needful nucleotides step by step. Thus molecular machine “sews” a new thread of DNA and corrects mistakes that polymerase occasionally admits in his “sewing” business. In the correct DNA helix, there are A in one thread against T the other and C against G. And we must also remember that DNA is complexed with proteins, forming chromatin; the latter forms chromosomes—particles that carry all the heredity, biological portrait, and history of the life of each and any creature. A human is known to have 46 chromosomes. The difference between men and women lies only in one of them.

Sections of the DNA chain, i.e., blocks of sequences of letters from the alphabet A, C, T, and G, make up the gene… However, not any section is a gene, but only one that encodes a certain protein. The totality of all genes is a genome. The word “encodes” means that this gene stimulates the synthesis of the selected protein and it is responsible for its appearance. It is here the bridge lies between the genome (or genotype) and phenotype (appearance and its external features).

The genetic code is a set of biological features inherent in the genome, and genetic coding is the operation of protein biosynthesis, i.e., the translation of the genetic code into protein content. Any sequence of three letters (three nucleotides) in the DNA chain is a “codon,” it corresponds to one amino acid in the protein to be built a given gene. Coding in terms of common sense is a strange process.

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