How many effective codons are there for the synthesis of twenty amino acids:

Concept:

• A codon is a sequence of three DNA or RNA nucleotides that encode for a specific amino acid or stop signal during protein synthesis (Translation).
• Full set of codons is called the genetic code and each codon encodes for a single amino acid.
• The genetic code includes Total 64 possible permutations, or combinations, of three-letter nucleotide sequences that can be made from the four nucleotides.

Explanation:

• Out of 64 codons, 61 codons code for amino acids and the rest 03 are stop codons, which do not specify any amino acids. So there are 61 effective codons for the synthesis of twenty amino acids.
• Stop Codon is called nonsense codons, which are amber (UAG) ochre (UAA) and opal (UGA). They encode no amino acid. The ribosome pauses and falls off the mRNA.
• UGG code for tryptophan
• UGC code for cysteine
• UAC code for tyrosine

Additional Information

• The start codon is AUG, which is encoded by the Methionine.

• For the Nonsense codon, no normal tRNA molecule exists, This nonsense codon causes the termination of translation, so these are called as stop Codon.

• The genetic code is described as degenerate, because a single amino acid may be coded by more than one codon.