Out of the 64 possible codons in the genetic code, 61 codons are coding for the 20 standard amino acids found in proteins. The reason for this is due to redundancy in the genetic code.
The genetic code is degenerate, meaning that multiple codons can code for the same amino acid. For example, the amino acid methionine is coded by the start codon AUG, but it is also coded by the codon GUG. Similarly, the amino acid leucine is coded by six different codons (UUA, UUG, CUU, CUC, CUA, CUG).
This redundancy allows for flexibility and error correction in the translation process. If a mutation occurs in the DNA sequence and changes one nucleotide in the codon, there is a higher chance that the same amino acid can still be incorporated into the protein due to the degenerate nature of the code.
Additionally, the three remaining codons (UAA, UAG, UGA) are known as stop codons or termination codons. These codons signal the end of the protein-coding sequence, rather than coding for an amino acid. When a ribosome encounters one of these stop codons, it terminates translation and releases the completed protein.
Overall, the redundancy in the genetic code allows for efficient and accurate protein synthesis, while the presence of stop codons ensures that protein synthesis is properly terminated.
why out of 64 codon only 61 is coded for 20 amino acids
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