50S Ribosomal Subunit

Definition

The 50S ribosomal subunit is one of the two main components that make up the bacterial ribosome, which is responsible for protein synthesis. It works in conjunction with the 30S ribosomal subunit to decode mRNA and synthesize polypeptides during translation.

5 Must Know Facts For Your Next Test

1. The 50S ribosomal subunit contains the peptidyl transferase center, which catalyzes the formation of peptide bonds between amino acids.
2. Antibacterial drugs like chloramphenicol and linezolid target the 50S ribosomal subunit, inhibiting protein synthesis and leading to bacterial cell death.
3. The 50S subunit is composed of the 5S, 5.8S, and 23S ribosomal RNAs, as well as over 30 ribosomal proteins.
4. The 50S subunit is responsible for the binding and positioning of tRNA molecules during the elongation stage of translation.
5. Mutations in the genes encoding the 50S ribosomal subunit can confer resistance to certain antibacterial drugs.

Review Questions

• Explain the role of the 50S ribosomal subunit in protein synthesis.
  • The 50S ribosomal subunit plays a crucial role in protein synthesis by housing the peptidyl transferase center, which catalyzes the formation of peptide bonds between amino acids. It works in conjunction with the 30S subunit to decode the mRNA template and facilitate the elongation of the polypeptide chain. The 50S subunit is responsible for binding and positioning the tRNA molecules during translation, ensuring the proper alignment of the amino acids for peptide bond formation.
• Describe how antibacterial drugs target the 50S ribosomal subunit to inhibit protein synthesis.
  • Certain antibacterial drugs, such as chloramphenicol and linezolid, specifically target the 50S ribosomal subunit to disrupt protein synthesis in bacterial cells. These drugs bind to specific regions of the 50S subunit, interfering with the binding and positioning of tRNA molecules or the catalytic activity of the peptidyl transferase center. By inhibiting the proper functioning of the 50S subunit, these antibacterial drugs prevent the formation of peptide bonds, ultimately leading to the cessation of protein synthesis and the death of the bacterial cell.
• Analyze the potential impact of mutations in the genes encoding the 50S ribosomal subunit on antibiotic resistance.
  • Mutations in the genes responsible for the structure and function of the 50S ribosomal subunit can confer resistance to certain antibacterial drugs that target this subunit. These mutations can alter the binding sites or the catalytic activity of the 50S subunit, rendering it less susceptible to the inhibitory effects of the drugs. As a result, the bacterial cell can continue to synthesize proteins and survive in the presence of the antibacterial agent. Understanding the mechanisms by which mutations in the 50S subunit genes contribute to antibiotic resistance is crucial for developing effective strategies to combat the growing problem of antimicrobial resistance.

Related terms

Ribosome: The cellular organelle responsible for protein synthesis, composed of the 30S and 50S ribosomal subunits.

30S Ribosomal Subunit: The smaller of the two ribosomal subunits, responsible for binding and decoding the mRNA template.

Peptidyl Transferase Center: The catalytic site within the 50S ribosomal subunit that facilitates the formation of peptide bonds during translation.