🧫organic chemistry ii review

key term - Codon

Definition

A codon is a sequence of three nucleotides in messenger RNA (mRNA) that corresponds to a specific amino acid or a stop signal during protein synthesis. Each codon plays a crucial role in translating the genetic information encoded in DNA into proteins, which are essential for various cellular functions. The sequence of codons determines the order of amino acids in a protein, influencing its structure and function.

5 Must Know Facts For Your Next Test

  1. There are 64 possible codons, consisting of 61 coding codons for amino acids and 3 stop codons that signal the termination of protein synthesis.
  2. The genetic code is degenerate, meaning that multiple codons can specify the same amino acid, providing a level of redundancy.
  3. Codons are read in a non-overlapping manner during translation, meaning that each nucleotide is part of only one codon.
  4. The first codon of an mRNA transcript is typically an AUG, which codes for methionine and serves as the start signal for translation.
  5. Mutations in codons can lead to changes in amino acid sequences, which may affect protein function and can contribute to various diseases.

Review Questions

  • How do codons contribute to the process of translation during protein synthesis?
    • Codons are essential during translation as they provide the instructions for assembling amino acids into proteins. Each three-nucleotide sequence in the mRNA corresponds to a specific amino acid, and as the ribosome reads these codons one at a time, it recruits the appropriate tRNA molecules carrying the corresponding amino acids. This sequential addition continues until a stop codon is reached, completing the polypeptide chain.
  • Discuss the implications of codon redundancy in the context of mutations and protein function.
    • Codon redundancy means that some amino acids can be encoded by more than one codon, which can mitigate the effects of mutations. For example, if a mutation changes one nucleotide in a codon but still results in the same amino acid being incorporated into the protein, it may not affect protein function. However, if a mutation alters a codon to specify a different amino acid or introduces a stop codon prematurely, it can lead to malfunctioning proteins or diseases.
  • Evaluate how understanding codons and their role in protein synthesis can aid in biotechnological applications such as gene editing.
    • Understanding codons is critical for biotechnological applications like gene editing because it allows scientists to design precise changes to DNA sequences that can lead to desired outcomes in protein production. By manipulating specific codons, researchers can correct mutations or engineer proteins with enhanced properties. This knowledge underpins techniques such as CRISPR-Cas9, which target specific genes for modification based on their nucleotide sequences, showcasing the importance of codons in advancing genetic engineering and therapeutic strategies.