Un espermatozoide realiza un vertiginoso viaje junto a sus congéneres. En su travesía, ascendiendo por el útero y la trompa de falopio, se encuentra con el óvulo, que ya ha sido abordado por muchos otros que han perecido. Finalmente, nuestro protagonista —que no, no era el primero en llegar, sino uno más del pelotón— es favorablemente seleccionado por el óvulo, y consigue entrar en el citoplasma de la célula. La conclusión es obvia: todas las células de un individuo proceden de una sola, y por lo tanto, todas presentan la misma carga genética.
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etiquetas: células , cuerpo , genoma , espermatozoide , zigoto 
Hace tiempo leí que se había descubierto que según la edad del padre, se iban acumulando muchas mutaciones en el genoma de los espermatozoides. Me dejó alucinado, pero no veo que aquí se mencione. ¿alguien sabe algo?
The observed human sperm mutation frequency cannot explain the achondroplasia paternal age effect
The lifelong spermatogonial stem cell divisions unique to male germ cell production are thought to contribute to a higher mutation frequency in males. The fact that certain de novo human genetic conditions (e.g., achondroplasia) increase in incidence with the age of the father is consistent with this idea. Although it is assumed that the paternal age effect is the result of an increasing frequency of mutant sperm as a man grows older, no direct molecular measurement of the germ-line mutation frequency has been made to confirm this hypothesis. Using sperm DNA from donors of different ages, we determined the frequency of the nucleotide substitution in the fibroblast growth factor receptor 3 (FGFR3) gene that causes achondroplasia. Surprisingly, the magnitude of the increase in mutation frequency with age appears insufficient to explain why older fathers have a greater chance of having a child with this condition. A number of alternatives may explain this discrepancy, including selection for sperm that carry the mutation or an age-dependent increase in premutagenic lesions that remain unrepaired in sperm and are inefficiently detected by the PCR assay.
www.pnas.org/doi/10.1073/pnas.232568699
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Sobre genes y edad:
The risk of genetic mutations with paternal age
Look through a microscope at the sperm of two healthy men – one older, one younger — and you won’t be able to tell much of a difference.
Dive deeper to the genetic level, though, and you may well see worlds of discrepancies. Some potentially alarming. And not just because microscope technology has improved.
All the way back in the 1930s, pioneering geneticist J. B. S. Haldane observed a strange pattern among families with lengthy histories of hemophilia: The gene responsible for the
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