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Monday, June 24, 2013

Genes and genetics, a bit of history

Everybody talks about genes these days, mainly keeping this old and crazy idea that genes can keep  hidden secrets, with no possibility of changes, but recent researches show how much we still have to learn from them, but first, a little bit of history...
Since far-off times humans have realized that many of their bodily and psychological characteristics as well as their diseases, concentrated in some families and that these traits tend to be inherited from one generation to another. Thus they figured out that genetics plays an important role in not only cognitive but human development in general. 
Learning, is not exempt from this influence, at one way or another, some skills are scheduled since before birth, but they will be modeled with  culture and environment influences that allows these primary skills. 

It's not the case beginning a debate on whether genetics has more weight than the environment or Vice Versa,  what this post wants to highlight is the existence of critical periods that can be, if necessary, be extended, thanks to brain plasticity and depend on learning strategies, ensure that a child can compensate the nature's shortcomings or caused by environment .

This is because sometimes is easy to put away the legacies that parents give their children genetically speaking, because it is controversial to talk about whether the role of the environment is more or less important than the genes (Velázquez, 2004). It is known that genes contribute much to the development, but the environment exacerbates or represses this input. To the end of the day, If how can we be  geniuses of music if we don't have access to a musical instrument?, why do certain activities are easier than others?, Why schools aren't able to create geniuses?. 

In order to answer all those questions, it would be interesting to explain a bit of history, to mention that studies on the genetic relationships began in the year of 1900 with some research from someone called Mendel, however is interesting to note that Mendel carried out his discoveries almost without a previous research history.

  The history of prior knowledge to Mendel studies dating back to biblical times, as in genesis, a reference that Jacob, employed a method is presented for their sheep and goats raised mottled offspring (Strathern, 1999), bt it was not until  1694, when Camerarius reported the existence of sexes in plants and carried out the first experiments on pollination.  

Years later, entre1761 and 1767 Kölreuter, had done  research on hereditary mechanisms using plants,  however, the findings of this research appeared to confirm the current genetic theories at the time (mixed bloods), since the intersection between different varieties of Nicotiana (Nicotiana tabacum is a herbaceous perennial plant, of the family of the Solanaceae, whose leaves occurs most of the tobacco consumed in the world today), originating a hybrid of intermediate appearance between the parents which concluded this was due to two factors that each parent contributed in the same proportion to the characteristics of the offspring. The factors found by Mendel is what we currently know as genes (Strathern, 1999) .

Between 1822 and 1824, three independent researchers, Knight, Goss and Seton, realized studies based on pea (peas), discovering the dominance of some characters in generation 1 and segregation of several hereditary features in generation 2; However, do not they studied later generations or the numerical distribution of the characteristics of each generation, so it was not possible to extend the data from their studies.
Returning with Mendel, it has been written that he was fond of plants and to improve crops, although there is evidence that initially worked with mice, activity that seemed somewhat out of place to their superiors, for what made a change of experimental material to over 14 species of plants (Mendel said in any writing that he did not believe that his superiors knew that plants have sex). 

The pea, plant that finally worked, is a hermaphroditic species which has no sex chromosomes and it is easy to cut the stamens, avoiding in this way the self fertilization. Traits studied in such plants by Mendel are stable, although not studied intermediate conditions. For the form of the seed employed 253 hybrid (filial generation 1, F1), which had been obtained from a cross between the smooth seed plants and plants of rough seed, which originated only smooth phenotype, and is inferred a single genetic formula (genotype, Ll). But when the hybrids are crossed, it obtained 7324 seeds, of which 5474 were smooth and rough skin 1850, which somewhat complicated first finds, this generation called it subsidiary 2, F2 (Morgado, 2001; Barahona, Suarez and Martínez, 2001).

However, despite all the essential knowledge to explain the genetic mechanisms, most of the information for your understanding was obtained in years after Mendel, with the discovery of the desoxyribonucleic acid (DNA) carried out by Johann Friedrich Miescher in 1868; nucleic acids name are due to Richard Altmann, who thus called them in 1879.

But in this historic journey, it's not possible to forget the findings of Watson and Crick, doctors who allowed to know that the genetic information is contained in the molecular structure of desoxyribonucleic acid (DNA) which is found on the inside of a nucleus of the cell, in structures called chromosomes. However their findings were made possible the work of Rosalind Franklin who was an expert in x-ray crystallography and that thanks to her work was possible to elucidate the structure of the DNA double helix. 

Thanks to the joint work of these researchers from Cambridge, is found that desoxyribonucleic acid is a type of macromolecule that is part of all living cells and that there is contained the genetic information necessary for the development and operation of known living organisms and some viruses, being responsible for its transmission of heritable traits to the next generation. Within the DNA is very organized and associated with different proteins, which forms the structure known as chromatin (Watson, 2000).


Barahona, A., Suárez, E. y Martínez, S. (2001) Filosofía e historia de la biología. México. Facultad de Ciencias. UNAM. 

Kaback, DB. (2013)  The modest beginning of one genome project. Genetics. 194 (2) 291-299.

Morgado, E. (2001) ¿Cuán Mendeliana es la patología genética humana?. Clínica y Ciencia vol. 1 Nº 3. 48-59.
Strathern, P. (1999) Crick, Watson y el ADN. Siglo Veintiuno Editores. España.

Vásquez  Laslop, M. y Velázquez Arellano, A. (2004) Genómica y el desarrollo de un nuevo individuo. En A. Velazquez (2004) Lo que somos y el genoma humano: des-velando nuestra identidad. Ediciones científicas universitarias. UNAM. FCE.

Watson, J. (2000) La doble hélice. Alianza Editorial. Madrid.

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