A DNA sequence encoding a five-amino acid polypeptide is given below.
...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...
...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...

What is the function of the Shine–Dalgarno sequence?

Key Concepts

Shine-Dalgarno Sequence

The Shine-Dalgarno sequence is a ribosomal binding site in bacterial mRNA, crucial for initiating translation. It is a short, conserved sequence located upstream of the start codon, allowing the ribosome to recognize and bind to the mRNA. This interaction facilitates the proper alignment of the ribosome with the mRNA, ensuring that translation begins at the correct site.

Translation Initiation

Translation initiation is the first step in protein synthesis, where the ribosome assembles around the mRNA. This process involves the recognition of the start codon (AUG) and the recruitment of the initiator tRNA, which carries the first amino acid. The Shine-Dalgarno sequence plays a vital role in this step by ensuring the ribosome is positioned correctly to start translating the mRNA into a polypeptide chain.

Polypeptide Synthesis

Polypeptide synthesis is the process by which amino acids are linked together in a specific sequence to form proteins. This process occurs in the ribosome during translation, where the genetic code in mRNA is read and translated into a corresponding sequence of amino acids. The correct functioning of the Shine-Dalgarno sequence is essential for the accurate synthesis of polypeptides, as it influences the efficiency and fidelity of translation.