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Genetic Variation

May 2, 2018

 

Genetic variation is an important process because it can be naturally selected for or against, and it is needed for organisms to survive in different environments and climates. It is also important because if everyone in a species was identical, then they could be easily killed by diseases. Prokaryotes (single celled organisms) can increase genetic variation through the asexual processes of transformation, transduction, and conjugation. These are also collectively known as horizontal acquisition. Transformation occurs when a bacterial cell dies and breaks apart, leaving its DNA free floating, where it can then be picked up by another bacterial cell and be put to use within it. 

 

Transduction is when a bacteriophage infects a host cell and hijacks it to create copies of itself. When these new viruses break free, they take some of their host cell’s DNA with them as they travel to new cells they will infect. These bacterial cells can then use the previous host cell’s DNA themselves. Conjugation is the transfer of a plasmid from one bacterial cell to another, when they link themselves. One bacteria will originally have a “pilus” that it can use to connect to another bacteria and pass on its “fertility plasmid”. Eukaryotes (more complicated organisms) also have three main ways that they increase genetic variation, however these occur sexually. These are crossing over, random (also called independent) assortment, and random fertilization. Crossing over occurs in meiosis 1 and is where homologous chromosome from a mother and a father exchange genetic information with each other. Random assortment also happens during meiosis when the two linked chromosomes split up and each daughter cell gets a different one. Random fertilization has to do with the odds of each specific sperm with its specific genetic material fertilizing a specific egg. Each time and of these things occur it is unique, causing variation. The process of genetic variation is vital to the survival of an organism.

 

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