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Did you know that because Dolly's DNA came from a six year old sheep, there were many questions about whether the cloning process had successfully reset the DNA to that of an embryo or whether Dolly carried artifacts in her DNA that would normally be found in an older animals. This led to speculation about what Dolly’s ‘genetic’ age was and whether she aged more quickly than a sheep that wasn’t a clone. Because Dolly was the first animal to be cloned from an adult cell, scientists did not fully know what happened to the donor DNA during cloning. Analysis of Dolly’s DNA when she was one year old showed that the protective caps on the end of her chromosomes (known as telomeres) were shorter than those of a normal sheep of the same age. Telomeres get shorter with age and it is possible that Dolly’s telomeres had not been fully renewed during the cloning process. However, the telomeres of other cloned animals have been found to be a similar length or even longer than those of normal animals. The reasons for these differences in telomere length are not completely clear and require further investigation.
