As a NASA biologist, you are studying alien cells found under the polar ice cap of Mars. You find that these cells contain RNA consisting of 10 different nucleotide bases, and proteins consisting of 76 different amino acids. You hypothesize that the smallest possible codons in the genetic code of these alien cells would contain how many nucleotide "letters" per codon?

2

Explanation:

Number of different nucleotides available = 10

If a codon would consist 2 nucleotides, possible combination of amino acids would be = 10 * 10 = 100

Proteins found in this region have 76 different types of amino acids which is less than the possible 100 amino acids. So, 2 nucleotides per codon should be enough to produce all the amino acids.

Hence, the smallest possible codons in the genetic code of these alien cells would contain 2 nucleotide letters per codon.