codon

Thân thiện

A student points to a codon chart in a biology textbook.

Definition

1. Noun:
   • A codon is a specific sequence of three adjacent nucleotides (the building blocks of DNA or RNA) that serves as a fundamental unit of the genetic code. Each codon provides the instruction for incorporating a single, specific amino acid into a growing protein chain or signals the start or stop of protein synthesis.

Examples of Usage

• Noun:
  • The codon AUG typically signals the start of translation and also codes for the amino acid methionine.
  • A point mutation can change a single nucleotide within a codon, potentially altering the amino acid it specifies.
  • Scientists analyzed the DNA sequence to identify every codon that instructs the ribosome to add a new amino acid.

Advanced Usage

• "Start codon": The specific codon (usually AUG) that signals the beginning of protein synthesis (translation).
  • The ribosome binds to the mRNA at the start codon.
• "Stop codon" (or "termination codon"): One of three specific codons (UAA, UAG, or UGA in RNA) that signals the end of protein synthesis.
  • Translation continues until the ribosome encounters a stop codon.
• "Synonymous codon": Different codons that code for the same amino acid. This property is known as the degeneracy or redundancy of the genetic code.
  • Leucine is encoded by six different synonymous codons.

Variants and Related Words

• Anticodon (n): A sequence of three nucleotides on a transfer RNA (tRNA) molecule that is complementary to and pairs with a specific codon on the messenger RNA (mRNA) during translation.
  • The tRNA's anticodon ensures the correct amino acid is added to the chain.

Synonyms

• Triplet: In genetics, this term is often used interchangeably with "codon" to refer to a set of three nucleotides.
• Genetic code word: A descriptive synonym emphasizing its role as a unit of information in the genetic code.

Related Phrases

• "Reading frame": The way nucleotides are grouped into consecutive, non-overlapping codons. A shift in the reading frame changes how the sequence is interpreted into codons.
  • A frameshift mutation disrupts the normal reading frame, altering all subsequent codons.
• "Codon usage bias": The phenomenon where some synonymous codons are used more frequently than others in the genome of an organism.
  • Codon usage bias can affect the efficiency of gene expression.

Học thuật

Noun

1. a specific sequence of three adjacent nucleotides on a strand of DNA or RNA that specifies the genetic code information for synthesizing a particular amino acid