Genetic code

Definition

The genetic code is the set of rules that defines how the sequence of nucleotides in DNA and RNA translates into the sequence of amino acids in proteins. This code is essential for the synthesis of proteins, which are crucial for cellular function and organismal development, linking the processes of transcription and translation in the flow of genetic information.

5 Must Know Facts For Your Next Test

1. The genetic code is nearly universal among all organisms, suggesting a common evolutionary ancestor.
2. There are 64 possible codons in the genetic code, but only 20 standard amino acids, meaning that some amino acids are coded for by multiple codons.
3. The genetic code includes start and stop signals, where AUG serves as the start codon and UAA, UAG, and UGA are stop codons.
4. The redundancy in the genetic code helps protect against mutations; changes in a codon may not necessarily alter the amino acid produced.
5. The translation process involves tRNA molecules that bring specific amino acids to the ribosome based on the matching anticodon with the corresponding mRNA codon.

Review Questions

• How does the structure of the genetic code facilitate protein synthesis?
  • The structure of the genetic code facilitates protein synthesis through its use of codons, which are triplet sequences of nucleotides that correspond to specific amino acids. This coding system allows ribosomes to read mRNA and assemble amino acids into proteins accurately. The redundancy of the code also provides a safety net against mutations, ensuring that many changes won't alter the final protein product significantly.
• What role do transcription and translation play in utilizing the genetic code?
  • Transcription and translation are two critical processes that utilize the genetic code to produce proteins. During transcription, the DNA sequence is transcribed into mRNA, which carries the genetic information from the nucleus to the ribosome. Translation then decodes this mRNA sequence into a chain of amino acids using tRNA molecules that match each codon to its corresponding amino acid, ultimately forming a functional protein.
• Evaluate how mutations in the genetic code can impact protein synthesis and organismal traits.
  • Mutations in the genetic code can have varying impacts on protein synthesis and consequently affect organismal traits. Some mutations may be silent, causing no change in the protein, while others can result in missense mutations that alter an amino acid, potentially affecting protein function. In more severe cases, nonsense mutations can create premature stop codons, leading to truncated proteins. Such changes can have profound implications on an organism's phenotype, health, and survival.

Related terms

codon: A codon is a sequence of three nucleotides in mRNA that corresponds to a specific amino acid or a stop signal during protein synthesis.

transcription: Transcription is the process by which the genetic information encoded in DNA is copied into messenger RNA (mRNA) as the first step in gene expression.

translation: Translation is the process where ribosomes synthesize proteins by decoding the mRNA sequence into a specific sequence of amino acids.