Genetic Codes (RNA & DNA Codons)

RNA Codons



Genetic Codes

 The genetic code is traditionally represented as a RNA codon table due to the biochemical nature of the protein translation process. However, with the rise of computational biology and genomics, proteins have become increasingly studied at a genomic level. As a result, the practice of representing the genetic code as a DNA codon table has become more popular. The DNA codons in such tables occur on the sense DNA strand and are arranged at a 5' → 3' directionality.

nonpolar

polar

basic

acidic

(stop codon)

		2nd base
		T		C		A		G
1st base	T	TTT	(Phe/F) Phenylalanine	TCT	(Ser/S) Serine	TAT	(Tyr/Y) Tyrosine	TGT	(Cys/C) Cysteine
		TTC	(Phe/F) Phenylalanine	TCC	(Ser/S) Serine	TAC	(Tyr/Y) Tyrosine	TGC	(Cys/C) Cysteine
		TTA	(Leu/L) Leucine	TCA	(Ser/S) Serine	TAA	Stop (Ochre)	TGA	Stop (Opal)
		TTG	(Leu/L) Leucine	TCG	(Ser/S) Serine	TAG	Stop (Amber)	TGG	(Trp/W) Tryptophan
	C	CTT	(Leu/L) Leucine	CCT	(Pro/P) Proline	CAT	(His/H) Histidine	CGT	(Arg/R) Arginine
		CTC	(Leu/L) Leucine	CCC	(Pro/P) Proline	CAC	(His/H) Histidine	CGC	(Arg/R) Arginine
		CTA	(Leu/L) Leucine	CCA	(Pro/P) Proline	CAA	(Gln/Q) Glutamine	CGA	(Arg/R) Arginine
		CTG	(Leu/L) Leucine	CCG	(Pro/P) Proline	CAG	(Gln/Q) Glutamine	CGG	(Arg/R) Arginine
	A	ATT	(Ile/I) Isoleucine	ACT	(Thr/T) Threonine	AAT	(Asn/N) Asparagine	AGT	(Ser/S) Serine
		ATC	(Ile/I) Isoleucine	ACC	(Thr/T) Threonine	AAC	(Asn/N) Asparagine	AGC	(Ser/S) Serine
		ATA	(Ile/I) Isoleucine	ACA	(Thr/T) Threonine	AAA	(Lys/K) Lysine	AGA	(Arg/R) Arginine
		ATG[A]	(Met/M) Methionine	ACG	(Thr/T) Threonine	AAG	(Lys/K) Lysine	AGG	(Arg/R) Arginine
	G	GTT	(Val/V) Valine	GCT	(Ala/A) Alanine	GAT	(Asp/D) Aspartic acid	GGT	(Gly/G) Glycine
		GTC	(Val/V) Valine	GCC	(Ala/A) Alanine	GAC	(Asp/D) Aspartic acid	GGC	(Gly/G) Glycine
		GTA	(Val/V) Valine	GCA	(Ala/A) Alanine	GAA	(Glu/E) Glutamic acid	GGA	(Gly/G) Glycine
		GTG	(Val/V) Valine	GCG	(Ala/A) Alanine	GAG	(Glu/E) Glutamic acid	GGG	(Gly/G) Glycine

^A The codon ATG both codes for methionine and serves as an initiation site: the first ATG in an DNA's coding region is where translation into protein begins.^[1]

A Mapping of Amino Acids and Stop Signals to DNA Codons

Amino Acid/Signal	Codons	Amino Acid/Signal	Codons
A	GCT, GCC, GCA, GCG	C	TGT, TGC
D	GAT, GAC	E	GAA, GAG
F	TTT, TTC	G	GGT, GGC, GGA, GGG
H	CAT, CAC	I	ATT, ATC, ATA
K	AAA, AAG	L	TTA, TTG, CTT, CTC, CTA, CTG
M	ATG	N	AAT, AAC
P	CCT, CCC, CCA, CCG	Q	CAA, CAG
R	CGT, CGC, CGA, CGG, AGA, AGG	S	TCT, TCC, TCA, TCG, AGT, AGC
T	ACT, ACC, ACA, ACG	V	GTT, GTC, GTA, GTG
W	TGG	Y	TAT, TAC
START	ATG	STOP	TAA, TGA, TAG