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DNA Internationally common abbreviation for the English term deoxyribonucleinacid. The German DNS (deoxyribonucleic acid) is hardly used anymore to avoid confusion with the Domain Name System (DNS) of the Internet. The structure of DNA was elucidated in 1953 by the biologists James Watson (*1928) and Francis Crick (1916-2004), who received the Nobel Prize for Medicine in 1962 with Maurice Wilkins (1916-2004).

The name is derived from the basic DNA building blocks deoxyribose (a type of sugar consisting of five carbon atoms, a pentose), phosphoric acid and four bases, which make up the nucleic acid. DNA is a chain molecule in the cell nuclei of all plant, animal and human organisms, which serves as a carrier of genetic information for the maintenance of all biological life processes and is inherited. The genes are responsible for each individual function in an organism, such as cell division or metabolism. However, they do not carry out these functions directly, but have "service organs" for them, the proteins, so to speak

The entire genetic material is called the genome, whereas a gene is a small section of DNA of varying size. The definition of the gene by 25 scientists of the Sequence Ontology Consortium of the University of Berkeley 2006: A gene is a locatable region of genomic DNA sequence corresponding to a unit of inheritance and associated with regulatory, transcribed and/or functional sequence regions. It contains basic information for the development of characteristics of an individual and for the production of a biologically active RNA (ribonucleic acid). An essential function of RNA in the biological cell is the conversion of genetic information into proteins

Structure of the DNA

The genes form a long chain molecule consisting of two counter-rotating DNA single strands in the form of a helically twisted rope ladder, also called double helix (hélix = turn). These are called chromosomes (colour bodies). This can be imagined as an extremely long, thin rope ladder. The length of DNA in a human cell is just under two metres. Since a human being consists of about 100 trillion cells (25% of which are blood cells that do not have a cell nucleus), the total length of DNA in a human being is 150 billion kilometres, which is about a thousand times the distance from the earth to the sun at about 150 million kilometres.

The two outer rods of the ladder consist of phosphoric acid and sugar molecules (deoxyribose). The connection of the pairs is the "rung", the two sides of the ladder are called "strands". The rungs consist of two of each of the four bases. These are adenine, guanine, cytosine and thymine. Of these four building blocks, there are always two that fit together like key and lock - A and T form one pair and C and G form the other pair. If, for example, one string says "TAACGCCCTTA", the other string is "ATTGCGGGAAT"

The graph shows a section of the DNA strand. A phosphoric acid ester and a sugar unit form the backbone of a molecule (part of the blue band). Together with a base, these three units form a nucleotide (red ellipses). The two nucleotides (ellipses) together form a macromolecule of the nucleic acid type deoxyribonucleic acid. In addition to their function as information stores, nucleic acids, which are considered to be the "key molecules of life", can also serve as signal transmitters or catalyse (support) biochemical reactions.

DNA - Doppel-Helix

One can call the ladder "genetic alphabet", where the order of the base pairs plays an extremely important role. The gene code is read (decoded) by the cell and thus the proteins are built.Proteins consist of amino acids. The individual proteins have very specific tasks. The sequence of the base pairs determines how proteins are composed and how the organism is made up with all its details. In humans, they determine the appearance (e.g. height, hair and eye colour) and characteristics (e.g. temperament, cause of diseases and also the talent or potential for a certain sport). However, environmental influences also play an equally important role when growing up. It is not yet clear whether genetics or environment play a more important role. What is clear is that there is an interaction and that, with regard to characteristics, one plays a greater role one time and the other another.

The DNA in the human genome is divided into 23 chromosomes (n = 23), which occur in duplicate (homologous) (2n = 46). One of each of the two chromosomes comes from the mother and the father. When passing on the genome to the next generation, the mother passes on only one of her two chromosomes to the child at a time. Together with the simple chromosome set of the father, a new diploid chromosome mixture is created. In addition, individual sections can be exchanged during the inheritance process (crossing over), so that each person has an exclusive and unmistakable genome pattern that is indeed "unique" in the truest sense of the word.

DNA - Schimpanse, 6 Menschenköpfe, Weintrauben und Weíngläser

Humans possess 20,000 to 25,000 genes (the exact number is still unknown), whereas the water flea, interestingly enough, possesses 30,000. It is not the number, but the interconnection and interaction of the genes that counts. By the way, the DNA of all humans, despite all individuality and uniqueness, is 99.9% identical. So the difference is only 0.1%, which can still mean big differences in appearance and abilities. There is less agreement between chimpanzees and orangutans than with 99% between chimpanzees and humans (but the differences are ten times greater than between two humans). A European and a black African can be more similar than two Europeans (skin colour is a completely insignificant detail). Therefore, the term "race", which is no longer relevant or used in science, is obsolete. By the way, the DNA of a grapevine is 50% identical to that of humans. In principle, this applies to many plants. Many processes such as metabolic processes are identical in humans, animals and plants


This phenomenon of a strongly pronounced heterozygosity (also heterozygosity, cleavage, inhomogeneity) is the reason for the individual appearance of each person, and is equally typical for grape varieties. Spontaneous mutations result in small changes in genetic information, which are passed on to the offspring and lead to the splitting of characteristics into many variants (alleles). Even cloned vines from vegetative propagation of a mother vine can disintegrate due to mutations in the genetic material, which is particularly common in very old vine varieties such as Gouais Blanc (Heunisch), Muscat, Pinot and Traminer.

All varieties of the vine subgenus Vitis have a diploid (i.e. double) chromosome set with 2x19 chromosomes (n = 19, 2n = 38). These are all Asian vines (such as Vitis amurensis, Vitis coignetiae, Vitis ficifolia etc.), European vines (Vitis vinifera) and most American vines (such as Vitis aestivalis, Vitis cinerea, Vitis labrusca, Vitis lincecumii, Vitis riparia, Vitis rupestris etc.). Due to the same chromosome numbers and the absence of crossing barriers, these can be crossed with each other largely without problems when breeding new grape varieties. However, there are also vine species such as the American Vitis rotundifolia with deviating chromosome numbers (n = 20, 2n = 40). If these are crossed with species of the subgenus Vitis, no or only sterile offspring are produced (2n = 39).

amereikanisch/europäische Hybriden

Identification of vine varieties

For identification or comparison between grape varieties, genetic information at specific gene locations (microsatellites) within the DNA chain is used. Six to eight microsatellites are usually sufficient for the identification of grape varieties. However, in order to be able to reliably prove ancestry or family relationships, about 25 gene locations are required. In molecular genetics, such sections are called "fingerprints". For some time now, the breeding of resistant grapevine varieties has also made use of manipulative genetic engineering, which is not without controversy. This involves introducing foreign genes with desired characteristics into the genome of plant cells of certain conventional varieties. In 2002, the INRA Institute developed the Nuclear Magnetic Resonance method to detect wine adulteration and to define the percentage of different grape varieties in a wine.

Cabernet Sauvignon - Kreuzung Cabernet Franc(Mutter) x Sauvignon Blanc (Vater)

Grapevine genome

In August 2007, the decoding of the vine genome was announced by Italian and French researchers. This makes it the first fruit-bearing plant whose DNA sequence is known. The scientists discovered some special features. Stilbene (an aromatic hydrocarbon), the enzyme responsible for the production of resveratrol, is present 43 times in the genome. The gene for the formation of the aromatic substance terpene exists in 89 variants. This is also the reason for the many different aromatic substances in wine. The comparison with other genomes also shows which plants the grapevine is related to. According to this, the vine genome is composed of three predecessor genomes and is more closely related to poplar than to rice. Knowledge of the genome could also be helpful in the case of pathogens by inducing resistance through genetic engineering measures. For the origin of a grape variety, see molecular genetics, for taxonomy, see grapevine systematics, and for keywords relevant to grape varieties, see grapevine.

Sources: Onmeda, Simlpy Science and WIKIPEDIA deoxyribonucleic acid
Double helix animated: From Zephyris, CC BY-SA 3.0, Link
Grapes and glasses: From Photo Mix on Pixabay
Human Heads: From Collective, CC BY-SA 3.0, Link
Chimpanzee: From suju on Pixabay
Grape varieties: Ursula Brühl, Doris Schneider, Julius Kühn Institute (JKI)

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