Question

you travel to another planet and discover that its genetic system is based on DNA,but there are 6 bases instead of 4 as happens on earth.the proteins on the planet have 30 amino acids.what is the likely number of letters in each codon on this planet?

Answer 1

On earth, DNA has 4 different bases and there are three bases in each codon.

So, total number of codons possible = 4³ = 64

But total number of amino acids = 20

Here we have to note that if there were only two letters in a codon, number of codons possible will be 4² = 16 and there won't be 20 amino acids. So, to constitute 20 amino acids, there should be atleast three letters in a codon.

On this 'another planet', there are 6 different bases and 30 amino acids.

So to constitute 30 amino acids:

If there are 2 letter in each codon, number of combinations is 6² = 36 which is greater than 31. (30 AA + 1 stop codon)

So, the minimum number of letters required in a codon to make 30 amino acids in this planet is 2.

Therefore, the answer is 2.