Question

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 thatthere are only 2 bases (a and t) in the martian dna, andthere 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

The right answer is 5.

To answer this question, we must think in the same way as the demonstration showing that codons of 3 are necessary to encode an amino acid (in terrestrial species).

To calculate the number of nucleotides in a codon in these new species: we should use the law of:

nucleotides existing ^ (number of nucleotides in a codon) = number of codons.  (in order to have the number of possible codon combinations)

The number of codons must be greater than or equal to the number of amino acids (17).

2 ^ 1 = 2 (<17)

2 ^ 2 = 4 (<17)

2 ^ 3 = 8 (<17)

2 ^ 4 = 16 (<17)

2 ^ 5 = 32  (> 17)

32> 17 so the number of nulceotides in a codon must be 5.