We know that the genetic code is universal. My query is why the mitochondrial genetic code is different from universal genetic code?
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asked Feb 23, 2016 at 11:24
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1 Answer
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Your premise is incorrect, the genetic code is NOT universal. There is a 'standard' genetic code, which is found among higher animals and plants and most bacteria, but there is a variety of other genetic codes found in the main genome of more obscure organisms. These are listed at: http://www.ncbi.nlm.nih.gov/Taxonomy/Utils/wprintgc.cgi .
There is also no mitochondrial genetic code but a variety of mitochondrial (and plastid) genetic codes. One feature of genomes with non-standard genetic codes is small size, so that the number of proteins influenced by a change from a common precursor genetic code would have been small.
In the case of mammalian mitochondria there are fewer tRNAs and these have non-standard anticodon-codon interactions. Thus rationalization of these genetic codes may have been due to pressure to reduce the size of the genome.
