Codon-anticodon pairing

Definition

Codon-anticodon pairing is the process in which a sequence of three nucleotides, called a codon, on mRNA pairs with its complementary sequence of three nucleotides, known as an anticodon, on tRNA during protein synthesis. This pairing is crucial for translating the genetic information carried by mRNA into a specific sequence of amino acids, ultimately forming proteins that perform various functions within living organisms. The accuracy of this pairing ensures that proteins are synthesized correctly according to the genetic code.

5 Must Know Facts For Your Next Test

1. Each tRNA molecule has a specific anticodon that corresponds to a particular amino acid, ensuring that the correct amino acid is added to the growing polypeptide chain during translation.
2. The codon-anticodon pairing follows strict base-pairing rules, where adenine pairs with uracil in RNA and cytosine pairs with guanine.
3. There are 64 possible codons in the genetic code, but only 20 amino acids, leading to multiple codons coding for the same amino acid, a phenomenon known as degeneracy.
4. Codon-anticodon pairing occurs within the ribosome, specifically in the A (aminoacyl) site, where new tRNA molecules enter and pair with mRNA codons.
5. Mispairing of codons and anticodons can lead to mutations or incorrect protein synthesis, emphasizing the importance of accurate base pairing in maintaining cellular function.

Review Questions

• How does codon-anticodon pairing contribute to the accuracy of protein synthesis?
  • Codon-anticodon pairing contributes to the accuracy of protein synthesis by ensuring that each tRNA molecule brings the correct amino acid corresponding to the mRNA codon being read. The specific matching between the codon on mRNA and the anticodon on tRNA is guided by complementary base pairing rules. This precision is crucial for assembling polypeptides in the correct order, which directly affects the function of the resulting protein.
• What are the implications of codon degeneracy for the evolutionary processes in organisms?
  • Codon degeneracy refers to the existence of multiple codons that can encode for the same amino acid. This redundancy can provide a buffer against mutations; changes in DNA that alter a codon may still result in the same amino acid being incorporated into a protein. Such flexibility can have important implications for evolutionary processes, allowing organisms to tolerate certain genetic variations without affecting protein function, which may help maintain vital cellular processes over generations.
• Evaluate how errors in codon-anticodon pairing could impact cellular functions and overall organism health.
  • Errors in codon-anticodon pairing can lead to incorrect amino acids being incorporated into proteins, resulting in dysfunctional proteins that may lose their normal function or gain harmful properties. Such misfolded or improperly assembled proteins can disrupt metabolic pathways, hinder cellular processes, and potentially lead to diseases. For example, some genetic disorders arise from single-point mutations that affect codon usage, highlighting how critical accurate pairing is for maintaining organismal health and proper biological functioning.

Related terms

mRNA:

Messenger RNA (mRNA) is a type of RNA that conveys genetic information from DNA to the ribosome, where it serves as a template for protein synthesis.

tRNA:

Transfer RNA (tRNA) is a molecule that transports amino acids to the ribosome during protein synthesis and has an anticodon that pairs with the corresponding codon on mRNA.

ribosome: The ribosome is a cellular structure that facilitates the assembly of amino acids into proteins by reading the sequence of codons on mRNA and coordinating the interaction between mRNA and tRNA.