Question

Part c - codon size and the genetic code life as we know it depends on the genetic code: a set of codons, each made up of three bases in a dna sequence and corresponding mrna sequence, that specifies which of the 20 amino acids will be added to the protein during translation. imagine that a prokaryote-like organism has been discovered in the polar ice on mars. interestingly, these martian organisms use the same dna → rna → protein system as life on earth, except that there are only 2 bases (a and t) in the martian dna, and there are only 17 amino acids found in martian proteins. based on this information, what is the minimum size of a codon for these hypothetical martian life-forms?

Answer 1

You need to be able to at least enough to have a unique code at each position. For example, 3 bases is enough for us because that is the minimum that gives a unique code for each. If there was only 2 bases, you would have only 16 unique combinations. You need to calculate the number of combinations for each length (which is # of base choices (2) to the x power, where x equals the number of positions). 1 position= 2^1 = 2 2 positions = 2^2 = 4 3 positions = 2^3 = 8 4 positions = 2^4 = 16 5 positions = 2^5 = 32 5 positions is the first that gives at least 17 unique codes so the minimum size of the martian codon is 5 bases.