Translation Components—What Is Not Needed? Which of the following is NOT a necessary component of the translation process (polypeptide synthesis on ribosomes)?

Introduction / Context:
Translation requires coordinated interactions between mRNA, tRNAs bearing anticodons and amino acids, and ribosomal subunits. Some enzymes are essential (e.g., aminoacyl-tRNA synthetases), whereas others belong to DNA repair or replication pathways. This question asks you to identify a component not required for translation.

Given Data / Assumptions:

• tRNA anticodon pairs with mRNA codon to ensure correct amino acid incorporation.
• Ribosomal subunits form the catalytic platform for peptide bond formation.
• Amino acids are substrates for polypeptide synthesis.

Concept / Approach:
DNA ligase seals nicks in DNA during replication and repair by forming phosphodiester bonds in DNA, not during protein synthesis. In translation, the relevant bond formation is the peptide bond, catalyzed by the ribosome's peptidyl transferase center (an rRNA-based activity), not a DNA ligase. Therefore, ligase is not a necessary component of translation, while the others are indispensable.

Step-by-Step Solution:

Verification / Alternative check:
In vitro translation systems lack DNA ligase yet synthesize proteins efficiently, while deleting tRNAs or ribosomes abolishes translation.

Why Other Options Are Wrong:

• Anticodon: required for codon recognition.
• mRNA: provides the template.
• Amino acids: building blocks of polypeptides.
• Ribosomal subunits: form the active ribosome.

Common Pitfalls:
Confusing enzymatic activities across DNA replication/repair and protein synthesis pathways.

Final Answer:
Ligase