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 essential for translating the genetic information encoded in DNA into proteins, which are critical for cellular function and structure. Codons are integral to the genetic code, determining how the sequence of nucleotides is read and interpreted by the cellular machinery involved in translation.

5 Must Know Facts For Your Next Test

1. There are 64 possible codons in the genetic code, with 61 codons specifying amino acids and 3 codons acting as stop signals that terminate protein synthesis.
2. Codons are read in a non-overlapping manner, meaning each nucleotide is part of only one codon, and this ensures accurate translation of the genetic information.
3. The genetic code is nearly universal across all living organisms, highlighting its fundamental role in biology and evolution.
4. Some amino acids are specified by more than one codon, which is referred to as redundancy or degeneracy in the genetic code.
5. Start codons, specifically AUG, not only signal the beginning of translation but also encode the amino acid methionine, which is often the first amino acid in newly synthesized proteins.

Review Questions

• How does a codon function within the context of translation, and what role does it play in determining the sequence of amino acids in a protein?
  • A codon functions as a fundamental unit in the process of translation by providing the instructions for incorporating specific amino acids into a growing polypeptide chain. Each codon, made up of three nucleotides on mRNA, corresponds to a particular amino acid or a stop signal. During translation, ribosomes read these codons sequentially, allowing tRNA molecules with matching anticodons to deliver the appropriate amino acids, thereby assembling them in the correct order to form functional proteins.
• Discuss how redundancy in the genetic code affects protein synthesis and what implications this has for mutations that may occur within codons.
  • Redundancy in the genetic code allows for multiple codons to encode the same amino acid, which can provide a buffer against mutations. If a mutation alters one nucleotide in a codon, it may still result in the same amino acid being incorporated into a protein due to this redundancy. This phenomenon can reduce the impact of certain mutations on protein function; however, if a mutation changes a codon to one that encodes a different amino acid or creates a stop signal prematurely, it can lead to dysfunctional proteins and potential cellular consequences.
• Evaluate how understanding codons and their role in translation contributes to advancements in genetic engineering and biotechnology.
  • Understanding codons and their specific functions in translation is crucial for advancements in genetic engineering and biotechnology because it enables scientists to manipulate gene expression and protein synthesis intentionally. By designing synthetic genes with specific codon sequences, researchers can enhance or alter protein production in organisms. This knowledge aids in developing targeted therapies, creating genetically modified organisms for agriculture or research purposes, and producing recombinant proteins for pharmaceuticals. The ability to predict how changes in codons affect protein outcomes underpins many innovations in biotechnology.

Related terms

anticodon: An anticodon is a sequence of three nucleotides on tRNA that is complementary to a specific codon on mRNA, ensuring the correct amino acid is added during protein synthesis.

genetic code: The genetic code is the set of rules that define how sequences of nucleotide triplets (codons) translate into amino acids, ultimately determining the structure and function of proteins.

amino acid: Amino acids are the building blocks of proteins, and there are 20 different types that combine in various sequences to form proteins based on the information provided by codons.