Which three-nucleotide unit in mRNA specifies a particular amino acid?

Which three-nucleotide unit in mRNA specifies a particular amino acid?

• A. Codon
• B. Anticodon
• C. Exon
• D. Intron

Answer: (A)

In mRNA, the unit of three nucleotides that specifies a particular amino acid is called a codon. The genetic code maps each codon to one amino acid (though some amino acids have multiple codons), and the ribosome reads these codons to add the correct amino acids in order during protein synthesis. The anticodon, by contrast, is a three-nucleotide region on tRNA that pairs with the codon to deliver the matching amino acid. Exons and introns are parts of genes: exons are the coding regions retained in mature mRNA, while introns are noncoding sequences removed during processing.

In mRNA, the unit of three nucleotides that specifies a particular amino acid is called a codon. The genetic code maps each codon to one amino acid (though some amino acids have multiple codons), and the ribosome reads these codons to add the correct amino acids in order during protein synthesis. The anticodon, by contrast, is a three-nucleotide region on tRNA that pairs with the codon to deliver the matching amino acid. Exons and introns are parts of genes: exons are the coding regions retained in mature mRNA, while introns are noncoding sequences removed during processing.