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1、,Unit 2,Cloning,Why plant “clones” arent identical 克隆后的植物与母体完全相同吗？植物克隆与动物克隆有区别吗？这种研究有什么意义呢？,单元话题阅读,Science Daily (Aug 4,2011)A new study of plants that are reproduced by cloning has shown why cloned plants are not identical. Scientists have known for some time that cloned organisms are not always id
2、entical：their observable characteristics and traits can vary，and this variation can be passed on to the next generation.This is despite the fact that they are derived (获得) from genetically identical founder cells.,Now，a team from Oxford University，the UK，and King Abdullah University of Science and T
3、echnology，Saudi Arabia，believe they have found out why this is the case in plants：the genomes (染色体) of regenerate plants carry relatively high frequencies of new DNA sequence mutations (变异) that were not present in the genome of the donor plant. The team reported their findings in this weeks Current
4、 Biology.,“Where these new mutations actually come from is still a mystery，” said Professor Harberd.“They may arise during the regeneration process itself or during the cell divisions in the donor plant that gave rise to the root cells from which the regenerate plants are created.We are planning fur
5、ther research to find out which of these two processes is responsible for these mutations.What we can say is that nature has safely been employing what you might call a cloning process in plants for millions of years，and that there must be good evolutionary reasons why these mutations are introduced
6、.”,The new results suggest that variation in clones of plants may have different underlying causes from those of variation in clones of animalswhere it is believed that the effect of environmental factors on how animal genes are expressed is more important and no similar high frequencies of mutation
7、s have been observed. Professor Harberd said，“While our results highlight that cloned plants and animals are very different，they may give us insights into how bacterial and cancer cells replicate themselves，and how mutations arise during these processes which，ultimately，have an impact on human health.”,谢谢观看！,
