Question

RECALL What is the role of the 50 S ribosomal subunit in prokaryotic protein synthesis?

Short answer

The 50 S ribosomal subunit catalyzes peptide bond formation and aids in tRNA positioning during protein synthesis.

Step-by-step solution

Identify the Context

Understand that the 50 S ribosomal subunit is a part of the prokaryotic ribosome, which plays a crucial role in protein synthesis by translating messenger RNA (mRNA) into proteins.

Understand Ribosomal Subunit Structure

Recognize that the prokaryotic ribosome is composed of two subunits: the smaller 30 S subunit and the larger 50 S subunit. The 50 S subunit is made up of ribosomal RNA (rRNA) and proteins.

Role in Peptide Bond Formation

The 50 S ribosomal subunit plays a critical role in forming peptide bonds between amino acids. Specifically, the peptidyl transferase center of the 50 S subunit catalyzes this process, which is essential for elongating the growing polypeptide chain.

Facilitation of Ribosomal Function

The 50 S subunit also aids in proper positioning of the tRNA molecules and ensures their accurate interaction with the mRNA. This facilitates the correct addition of amino acids to the polypeptide chain.

Overview of Translation

During translation, the 50 S subunit, along with the 30 S subunit, moves along the mRNA. The 50 S subunit's functions are crucial during the elongation phase of protein synthesis.

Key concepts

ribosomal subunits

In prokaryotic cells, protein synthesis takes place within the ribosome, an essential cellular machine. Ribosomes are made up of two subunits: the 30 S and the 50 S. Each subunit has unique roles in the translation process. The 30 S subunit is responsible for decoding the mRNA, ensuring that the correct tRNA is matched with the mRNA codon. On the other hand, the 50 S subunit is larger and plays a pivotal role in catalyzing the formation of peptide bonds. Understanding the structure and function of these subunits is key to grasping how proteins are synthesized within cells.

protein synthesis

Protein synthesis is the process by which cells build proteins, which are essential for various cellular functions. This process involves two main stages: transcription and translation. During transcription, the genetic information in DNA is copied into mRNA. Translation is the next step, where the information contained in the mRNA is used to assemble amino acids into a polypeptide chain, forming a protein. This assembly happens in the ribosome, where the 50 S subunit plays a crucial role.

peptidyl transferase center

The peptidyl transferase center (PTC) is a vital component of the 50 S ribosomal subunit. It catalyzes the formation of peptide bonds between amino acids during protein synthesis. The PTC ensures that each new amino acid is correctly added to the growing polypeptide chain. This catalytic activity is essential for the elongation phase of translation, as it facilitates the linking of amino acids into a continuous chain. Without the PTC, the ribosome would not be able to build proteins effectively.

translation

Translation is a critical phase of protein synthesis where the mRNA is decoded to produce a specific polypeptide. It takes place in the ribosome and involves several steps: initiation, elongation, and termination. During initiation, the ribosome assembles around the target mRNA. Elongation is where amino acids are sequentially added to the growing polypeptide chain, facilitated by the peptidyl transferase activity within the 50 S subunit. Finally, termination occurs when a stop codon is reached, signaling the end of the protein synthesis process and releasing the newly formed protein.

tRNA positioning

tRNA molecules play an essential role in translation by bringing the correct amino acids to the ribosome based on the mRNA codon sequence. The 50 S ribosomal subunit ensures the accurate positioning and interaction of tRNA with the mRNA. This precise positioning is crucial for the addition of the correct amino acid to the polypeptide chain. It helps maintain fidelity in the protein synthesis process, ensuring that proteins are built accurately according to the genetic instructions encoded in the mRNA.