Researchers compared the amino acid sequences of the transport protein in zebrafish, 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? Explain why or why not.

Amino acid sequences are the specific order of amino acids in a protein, which determine its structure and function. These sequences are encoded by the corresponding mRNA, which is transcribed from DNA. Identical amino acid sequences across different species suggest evolutionary conservation, but do not guarantee that the mRNA sequences are identical due to potential variations in codon usage.

mRNA (messenger RNA) is a type of RNA that carries genetic information from DNA to the ribosome, where proteins are synthesized. The mRNA is composed of codons, which are sequences of three nucleotides that correspond to specific amino acids. Different organisms may use different codons to code for the same amino acid, a phenomenon known as codon bias, which means that identical amino acid sequences can arise from different mRNA sequences.

Evolutionary conservation refers to the preservation of certain biological traits, such as amino acid sequences, across different species due to their functional importance. When researchers find identical sequences in multiple species, it indicates that these sequences have been maintained through evolution, likely because they confer a selective advantage. However, this conservation does not imply that the underlying genetic sequences (mRNA or DNA) are identical, as evolutionary processes can lead to divergence at the genetic level.