Answered

During translation, nucleotide base triplets (codons) in mRNA are read in sequence in the $5^{\prime} \rightarrow 3^{\prime}$ direction along the mRNA. Amino acids are specified by the string of codons. What amino acid sequence does the following mRNA nucleotide sequence specify?



$5^{\prime} \text { - AUGGCAAGAAAA - } 3^{\prime}$



Express the sequence of amino acids using the three-letter abbreviations, separated by hyphens (e.g., Met-Ser-Thr-Lys-Gly).

Verified Answer :

  • Break the mRNA sequence \(5^{\prime}\text{-AUGGCAAGAAAA-}3^{\prime}\) into the codons AUG, GCA, AGA, and AAA.
  • Translate each codon according to the genetic code: AUG is Met, GCA is Ala, AGA is Arg, and AAA is Lys.
  • Join the abbreviations with hyphens to form the final protein segment.
  • The resulting amino acid sequence is \(\boxed{\text{Met-Ala-Arg-Lys}}\).

Explanation

  1. Analyzing the mRNA Sequence

The translation of mRNA into an amino acid sequence relies on reading the genetic code, which consists of triplets of nucleotides called codons. Each codon specifies a particular amino acid. The given mRNA sequence is \(5^{\prime} \text {- AUGGCAAGAAAA - } 3^{\prime}\). To determine the amino acid sequence, we must first break the mRNA strand into non-overlapping triplets starting from the \(5^{\prime}\) end.

  1. Identifying Codons

We partition the sequence AUGGCAAGAAAA into four consecutive codons:

  1. AUG
  2. GCA
  3. AGA
  4. AAA
  1. Mapping Codons to Amino Acids

By consulting the universal genetic code, we map each codon to its corresponding amino acid:

  • AUG codes for Methionine (Met).
  • GCA codes for Alanine (Ala).
  • AGA codes for Arginine (Arg).
  • AAA codes for Lysine (Lys).
  1. Final Amino Acid Sequence

Combining these amino acids in the order specified by the mRNA sequence, we obtain: Met-Ala-Arg-Lys. The final sequence is \(\boxed{\text{Met-Ala-Arg-Lys}}\).

Examples

Understanding how genetic information is decoded is the foundation of molecular biology. For example, when a cell needs to synthesize a specific protein to repair damage or signal a change in the environment, it translates the precise instructions contained within mRNA. This process of converting a sequence of nucleotides into a sequence of amino acids allows cells to build the complex machinery, such as enzymes and structural proteins, necessary for all life functions.

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