Codon

Definition

A codon is a sequence of three nucleotides in DNA or RNA that corresponds to a specific amino acid or a stop signal during protein synthesis. Each codon plays a critical role in the genetic code, directing the assembly of proteins by determining the sequence of amino acids in a polypeptide chain. This process involves transcription, where DNA is converted to RNA, and translation, where the mRNA codons are read to build proteins.

5 Must Know Facts For Your Next Test

1. Codons are found in messenger RNA (mRNA) and are essential for translating genetic information into proteins.
2. There are 64 possible codons in the genetic code, with 61 coding for amino acids and 3 serving as stop signals that terminate protein synthesis.
3. The genetic code is nearly universal, meaning that most organisms share the same set of codons for coding amino acids, which highlights a common evolutionary ancestry.
4. Each amino acid may be specified by more than one codon, leading to redundancy in the genetic code; for example, both UUA and UUG code for leucine.
5. Mutations in codons can lead to changes in amino acids during protein synthesis, potentially altering protein function and affecting cellular processes.

Review Questions

• How do codons function during the process of protein synthesis?
  • Codons serve as the basic units of information during protein synthesis by encoding the sequence of amino acids that will make up a protein. In transcription, DNA is transcribed into mRNA, where each codon consists of three nucleotides that correspond to specific amino acids. During translation, ribosomes read these codons one by one, facilitating the recruitment of tRNA molecules with complementary anticodons that carry the appropriate amino acids for protein assembly.
• Discuss how the redundancy of the genetic code impacts genetic mutations related to codons.
  • The redundancy of the genetic code means that multiple codons can encode the same amino acid. This feature provides a buffer against mutations; if a single nucleotide change occurs in a codon but results in the same amino acid being incorporated into the protein, this is known as a silent mutation and typically does not affect protein function. However, if a mutation leads to a different amino acid being incorporated (missense mutation) or introduces a stop signal (nonsense mutation), it can have significant impacts on protein structure and function.
• Evaluate the significance of understanding codons and their role in the genetic code for advancements in biotechnology and medicine.
  • Understanding codons and their roles in the genetic code is crucial for advancements in biotechnology and medicine because it underpins many techniques such as gene editing, synthetic biology, and personalized medicine. For instance, knowledge about how specific codons relate to particular amino acids allows scientists to design genes that produce desired proteins for therapeutic uses. Additionally, understanding mutations in codons can help in developing targeted therapies for genetic disorders by correcting errors at the DNA level or creating custom mRNAs for therapeutic applications. This knowledge also enhances our ability to create genetically modified organisms with beneficial traits.

Related terms

amino acid: The building blocks of proteins, each defined by specific codons and linked together through peptide bonds.

anticodon: A sequence of three nucleotides on tRNA that is complementary to a specific mRNA codon, allowing for the correct incorporation of amino acids during translation.

genetic code: The set of rules by which information encoded in genetic material is translated into proteins, consisting of codons that specify particular amino acids.