作业帮为什么RNA聚合酶保真度比DNA低?同一基因为什么会转录出多mRNA?
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/03 06:34:17
为什么RNA聚合酶保真度比DNA低?同一基因为什么会转录出多mRNA?
为什么RNA聚合酶保真度比DNA低?同一基因为什么会转录出多mRNA?
为什么RNA聚合酶保真度比DNA低?同一基因为什么会转录出多mRNA?
DNA聚合酶有校对功能,而RNA聚合酶没有校对功能,所以发生错配的话DNA聚合酶可以自我修正,而RNA聚合酶则不可以.这样RNA聚合酶保真度就比DNA聚合酶低.
转录出多条mRNA的情况多在原核生物中出现,真核生物一个基因编码一条多肽链,即转录一条mRNA.一,由于原核生物的基因组相对要小,多数基因按功能相关成串排列,是多顺反子的,而不像真核的是但顺反字,因此会同时携带不同蛋白的基因；二,多顺反子mRNA也有可能切割成多个单独的mRNA,避免了mRNA过长形成二级三级结构组织翻译进行.
Both DNA and RNA polymerases make mistakes during nucleotide chain elongation. But DNA polymerase can correct its errors by 3' nuclease activity, while RNA polymerase doesn't have such activity. There...
全部展开
Both DNA and RNA polymerases make mistakes during nucleotide chain elongation. But DNA polymerase can correct its errors by 3' nuclease activity, while RNA polymerase doesn't have such activity. Therefore, fidelity of DNA polymerase is higher than RNA ploymerase.
But the error effects by RNA polymerase are relatively minimized by the fact a non-sense RNA may be degraded faster and the fact the true half life of an mRNA is very short. If you consider the RNAs that have longer half life, like pol III ones, the copy number of them is so great that you have plenty fully functional ones and that drive the incorrect one negligible.
收起
RNA聚合酶没有外切核酸酶活性，而DNA聚合酶有，所以DNA聚合酶复制的保真度高。同一基因转录后经过不同的剪切，就可以得到不同mRNA，这发生在真核细胞里。