Transfer RNA

Definition

Transfer RNA (tRNA) is a type of RNA molecule that plays a crucial role in the process of translation by transporting amino acids to the ribosome, where proteins are synthesized. Each tRNA molecule has a specific anticodon that pairs with the corresponding codon on messenger RNA (mRNA), ensuring that the correct amino acid is added to the growing polypeptide chain. This pairing is essential for accurate protein synthesis, as it allows the genetic code to be translated into functional proteins.

5 Must Know Facts For Your Next Test

1. Each tRNA molecule carries a specific amino acid and has a unique anticodon that is complementary to an mRNA codon.
2. tRNAs are charged with their respective amino acids by enzymes called aminoacyl-tRNA synthetases, which ensure accurate matching between tRNAs and amino acids.
3. During elongation in translation, tRNAs enter the ribosome at the A site, then move to the P site after their amino acid is added to the growing polypeptide chain.
4. tRNA molecules are recycled after delivering their amino acids; they can be recharged with new amino acids for further rounds of translation.
5. There are 20 different amino acids but multiple tRNA molecules can recognize the same codon due to the wobble hypothesis, which allows for some flexibility in base pairing.

Review Questions

• How does transfer RNA ensure that the correct amino acid is added during protein synthesis?
  • Transfer RNA ensures the correct amino acid is added during protein synthesis through its unique structure and function. Each tRNA has an anticodon that pairs specifically with a codon on the mRNA strand, which encodes for a particular amino acid. This precise matching process guarantees that as ribosomes read the mRNA, the corresponding amino acids are brought in by their respective tRNAs, leading to accurate polypeptide formation.
• What role do aminoacyl-tRNA synthetases play in the function of transfer RNA during translation?
  • Aminoacyl-tRNA synthetases are crucial enzymes that facilitate the charging of tRNAs with their corresponding amino acids. Each enzyme is specific for one amino acid and its matching tRNA, ensuring that the correct amino acid is linked to its tRNA before translation begins. This step is essential because any mismatch could lead to errors in protein synthesis, resulting in nonfunctional or harmful proteins.
• Evaluate how the wobble hypothesis impacts the efficiency of protein synthesis and its significance in genetic coding.
  • The wobble hypothesis significantly enhances the efficiency of protein synthesis by allowing multiple tRNAs to recognize and bind to the same mRNA codon. This flexibility in base pairing at the third position of codons means that fewer tRNA types are needed than there are codons, simplifying cellular machinery and resources. This adaptability also plays an important role in genetic coding, as it helps buffer against mutations; certain changes in DNA can still lead to functional proteins despite variations in codon usage.

Related terms

Amino Acid: The building blocks of proteins, which are linked together in a specific sequence to form polypeptides.

Ribosome: The cellular machinery that facilitates the translation of mRNA into protein by coordinating the interaction between tRNA and mRNA.

Codon: A sequence of three nucleotides on mRNA that corresponds to a specific amino acid or stop signal during protein synthesis.