Q29-31E - Organic Chemistry (Mcmurry)

Question

Give an mRNA sequence that will code for the synthesis of metenkephalin.

Tyr-Gly-Gly-Phe-Met

Step-by-Step Solution

Answer

The mRNA sequence that will code for the synthesis of metenkephalin is,

• UAA GGG GGG UUU AUG
• UAC GGG GGG UUU AUG
• UAA GGA GGG UUU AUG
• UAC GGA GGG UUU AUG
• UAA GGA GGC UUC AUG
• UAA GGC GGU UUU AUG
• UAC GGA GGC UUC AUG
• UAC GGC GGU UUU AUG
• UUU GGA GGU UUC AUG

Step 1: Introduction

Transcribing DNA into mRNA is a complex process. Codons, which are tripeptide sequences that code for specific amino acids in the protein, are found in the mRNA.

Step 2: Tripeptide sequence of codon

The sequence of codons has the following characteristics:

The requirements for the first two nucleotide positions are quite stringent.

Because the nucleotide's third position is a variation, a shift in the tripeptide third nucleotide does not always signal a change in the amino acid incorporated.

Step 3: Tabulation for the amino acid codon

Amino acid	Codons
Tyr	UAA, UAC
Gly	GGU, GGA, GGC, GGG
Phe	UUU, UUC
Met	AUG

The codons are in $5^{\text{'}} \text{to} 3^{\text{'}}$ direction is,

• UAA GGG GGG UUU AUG
• UAC GGG GGG UUU AUG
• UAA GGA GGG UUU AUG
• UAC GGA GGG UUU AUG
• UAA GGA GGC UUC AUG
• UAA GGC GGU UUU AUG
• UAC GGA GGC UUC AUG
• UAC GGC GGU UUU AUG
• UUU GGA GGU UUC AUG

There are several mRNA sequence which will translate to give the given peptide sequence.