Codon does not contain which nucleic acid?

Ans. is 'd' i.e., Thymdine* Codon is a combination of 3 nucleotides present in mRNA, that can code for an aminoacid* Since it is present in RNA, it can include 3 of the 4 nucleotides - A, U, G, C (never thymidine)* Totally there are 64 codons* Out of the 64, 3 are stop codons (UGA, UAG, UAA)* Hence 61 codons code for 20 aminoacids* Property of genetic codeDegeneracy# As 61 codons code for 20 aminaocids, more than 1 codon can code for a single aminoacid. This is called as degeneracy.# The two aminoacids which do not follow degeneracy are :i) Methionineii) TryptophanUnambiguous# Not more than 1 aminocid can be coded by a single codonNon Overlapping# Never one codon is overlapped with the next (If the 1,2,3 nucleotides are considered as the 1st codon, 4,5,6 nucleotides will be considered as the 2nd codon... we don't include 3,4,5 as the 2nd codon)Not punctuated# After every 3 nucleotides, we don't have a punctuation. That is why frame shift mutation is possibleUniversal# Genetic code is the same in any cell# Exceptions - In mitochondrial DNA, UGA is not a stop codon, it codes for tryptophan and AGA and AGG do not code for Arginine, both act as stop codons.