DNA Sequences Occurs at Many Scales within Genomes Discussion

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Today it is widely believed that there are two fundamental ways in which genomes evolve; namely evolution by (1) duplication of pre-existing regions of DNA within the genome and (2) lateral gene transfer. (Brown, 2002), (Zhaxybayeva & Doolittle, 2011). The focus of this essay will be on DNA duplication, its occurrence, and it’s consequences in genomes at a molecular and organismal level. DNA duplication refers to the process by which a region of DNA already present in an organism’s genome is duplicated in that organism. The duplication of DNA has long been considered an important factor in the evolution of genomes. (Taylor & Raes, 2004) Although the duplication of DNA itself does not directly cause gene diversification and thus genome evolution, it does provide the potential for gene diversification to occur. It is true that DNA duplication occurs at many scales within genomes. DNA duplication can occur at the chromosomal level, where an extra copy of a particular chromosome becomes present in an organism. Chromosomal duplication may arise as a result of stress - some organisms’ duplicate genes in response to a particular environment. (Sheltzer et al, 2012) Chromosomal duplication offers a quick way for some organisms to adapt to a stressful environment, but can be be costly for a cell because of results in changes to normal cell metabolism as well as increased energy expenditure. (Yona et al, 2012) In yeast it’s apparent that chromosomal duplication occurs as a quick response to stress, but is slowly replaced by more efficient solutions through gene silencing or deletion. Chromosomal duplication can happen during meiosis if homologous chromosomes fail to separate during meiosis. Similarly, aneuploidy can also arise if sister chro...

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