Assume that you identified a new organism that surprisingly only uses 2 nucleoti
ID: 70624 • Letter: A
Question
Assume that you identified a new organism that surprisingly only uses 2 nucleotides to define each codon of the genetic code. Which inferences can be made based on this discovery? Consider how this change from 3 to 2-nucleotide codon impacts processes of transcription and translation, and genetic code structure? Would there be any impact on protein structure, function, and diversity? Finally, articulate the possible advantages for this organism to only use 2 nucleotides to define codon instead of the usual triplet.
Explanation / Answer
On the basis of this discovery it may be inferred that the organism is a very ancient organism when the three codon system had not evolved. The two things worth mentioning are that this organism would have restricted evolvability because of less variety of codons. Their would be no redundancy of codons.
The two codon system would drastically reduce the number of codons required to code for amino acids. Similarly such a codon system would only code for about 16 amino acids as 42 = 16, where 4 is the total number of nucleotides. The transcription would be relatively fast as the mRNAs would be small.
The protein structure would be coded by these codons. Since the number of nucleotides per codon has decreased, the probability of error due to mutation would increase and hence any kind of mutation would directly affect the sequence of proteins. Any change in protein sequence would affect the structure function and also diversity of the protein.
The advatnges would be less expenditure of free energy in the metabolism and synthesis of all the amino acids, Since the number of amino acids are less, the free energy spent on the synthesis of amino acids would be less. The genetic code would be simple and the overall mechanism of genome expression would be highly simplified as compared to a three nucleotide codon system.