You have isolated a gene that spans a total of 1800 nucleotides. The gene contains 400 nucleotides within 4 exons and 900 nucleotides are associated with the 3 introns. In addition there are 500 nucleotides associated with the regulatory sequences of the gene. Given this information, which of the following numbers most likely represents the number of amino acids encoded by this gene?

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Quizplus · Accepted Answer

The gene contains 400 nucleotides within exons, which are the coding regions. Since each amino acid is encoded by a codon of 3 nucleotides, the number of amino acids is 400/3, approximately 133. Therefore, 130 is the closest option. The coding region of any given gene is contained within the exons. The introns are removed from the mRNA following processing. It is possible for all or a part of any given 5′ and 3′ exon to be noncoding, but this information was not provided. Therefore, the most likely number of encoded amino acids in this gene is determined from the number of nucleotides comprising the exons. Since each amino acid is encoded by 3 nucleotides, the closest number to that which could be encoded by 400 nucleotides is 130.

You Have Isolated a Gene That Spans a Total of 1800