Skin color is often one of the first traits people notice in each other. Studies in zebra fish uncovered a mutation that altered a transport protein and resulted in light-colored fish. This discovery led to the finding that the same gene in humans has a strong influence on skin pigmentation in many populations.

Researchers compared the amino acid sequences of the transport protein in zebra fish, puffer fish, mice, and humans. They found many stretches with identical sequences in all four species. Does this mean that the corresponding mRNA base sequences are also the same in these four species?

The correct answer is: No.

Explanation:

Proteins, obtained from different species, having identical sequences of amino acids does not mean that their gene or the mRNA (messenger Ribonucleic Acid) will also have an identical sequence. This is because of the degeneracy in the genetic code. Three consecutive nucleotides (triplets) in the mRNA sequence codes for an amino acid molecule. These triplets are also called the Codons. However, the specificity of a particular amino acid is determined by the first two nucleotides in the codon. The third nucleotide is wobble or degenerate. This means that the nucleotide in the third position of a codon cannot alter the amino acid specified by the first two nucleotides in the codon. The mRNA sequences, encoding the protein, obtained from different species may vary in the wobble nucleotide position and hence the mRNA sequence can be distinctly different in different species.