Codon

Definition

A codon is a sequence of three nucleotides in mRNA that corresponds to a specific amino acid or a stop signal during protein synthesis. Each codon is part of the genetic code, which dictates how the information in genes is translated into proteins. The order of codons determines the sequence of amino acids in a protein, ultimately influencing its structure and function.

5 Must Know Facts For Your Next Test

1. There are 64 possible codons in the genetic code, including 61 codons that specify amino acids and 3 stop codons that signal the termination of protein synthesis.
2. The genetic code is nearly universal across all organisms, indicating its essential role in biology and evolution.
3. Codons are read in a sequential manner by ribosomes during translation, ensuring the correct order of amino acids is assembled into a protein.
4. Some amino acids are encoded by more than one codon, a feature known as redundancy or degeneracy in the genetic code.
5. Mutations can occur when there is a change in the nucleotide sequence of codons, potentially leading to changes in protein structure and function.

Review Questions

• How do codons influence the process of protein synthesis?
  • Codons play a critical role in protein synthesis by providing the instructions for assembling amino acids into polypeptide chains. Each codon corresponds to a specific amino acid, and ribosomes read these codons sequentially as they translate mRNA into proteins. This sequence determines the order and composition of amino acids, which ultimately defines the structure and function of the resulting protein.
• Discuss the significance of redundancy in the genetic code regarding codons and amino acids.
  • Redundancy in the genetic code means that multiple codons can encode for the same amino acid. This feature provides a buffer against mutations since changes in some codons may not result in altered amino acids, helping maintain protein function despite potential errors. This flexibility is crucial for evolution and adaptation, allowing organisms to withstand genetic variations without compromising vital biological processes.
• Evaluate how mutations in codons can affect protein function and potentially lead to disease.
  • Mutations in codons can lead to changes in the corresponding amino acids during protein synthesis, which can disrupt normal protein folding and function. If a mutation results in an incorrect amino acid being incorporated into a protein, it may affect the protein's activity or stability, potentially leading to diseases such as sickle cell anemia or cystic fibrosis. The severity of these effects depends on the specific roles of the altered protein and its impact on cellular processes.

Related terms

amino acid: Organic compounds that combine to form proteins, essential for various biological processes and functions.

mRNA (messenger RNA): A type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized.

anticodon: A sequence of three nucleotides in tRNA that pairs with a complementary codon in mRNA during translation.