Each triplet of bases in DNA codes has a specific meaning, typically identifying an amino acid. The code is degenerate, since most amino acids may be coded by more than one codon.
Bases in triplet:
(1) 5'-OH terminal base
(2) middle base
(3) 3'-OH terminal base
1st base |
2nd Base |
3rd Base |
Amino Acid |
---|---|---|---|
U |
U |
U |
phenylalanine |
U |
U |
C |
phenylalanine |
U |
U |
A |
leucine |
U |
U |
G |
leucine |
U |
C |
U |
serine |
U |
C |
C |
serine |
U |
C |
A |
serine |
U |
C |
G |
serine |
U |
A |
U |
tyrosine |
U |
A |
C |
tyrosine |
U |
A |
A |
STOP |
U |
A |
G |
STOP |
U |
G |
U |
cysteine |
U |
G |
C |
cysteine |
U |
G |
A |
STOP |
U |
G |
G |
tryptophan |
C |
U |
U |
leucine |
C |
U |
C |
leucine |
C |
U |
A |
leucine |
C |
U |
G |
leucine |
C |
C |
U |
proline |
C |
C |
C |
proline |
C |
C |
A |
proline |
C |
C |
G |
proline |
C |
A |
U |
histidine |
C |
A |
C |
histidine |
C |
A |
A |
glutamine |
C |
A |
G |
glutamine |
C |
G |
U |
arginine |
C |
G |
C |
arginine |
C |
G |
A |
arginine |
C |
G |
G |
arginine |
A |
U |
U |
isoleucine |
A |
U |
C |
isoleucine |
A |
U |
A |
isoleucine |
A |
U |
G |
methionine |
A |
C |
U |
threonine |
A |
C |
C |
threonine |
A |
C |
A |
threonine |
A |
C |
G |
threonine |
A |
A |
U |
asparagine |
A |
A |
C |
asparagine |
A |
A |
A |
lysine |
A |
A |
G |
lysine |
A |
G |
U |
serine |
A |
G |
C |
serine |
A |
G |
A |
arginine |
A |
G |
G |
arginine |
G |
U |
U |
valine |
G |
U |
C |
valine |
G |
U |
A |
valine |
G |
U |
G |
valine |
G |
C |
U |
alanine |
G |
C |
C |
alanine |
G |
C |
A |
alanine |
G |
C |
G |
alanine |
G |
A |
U |
asparagine |
G |
A |
C |
asparagine |
G |
A |
A |
glutamine |
G |
A |
G |
glutamine |
G |
G |
U |
glycine |
G |
G |
C |
glycine |
G |
G |
A |
glycine |
G |
G |
G |
glycine |
where:
• A triplet codon ending in a U or C codes for the same amino acid.
Amino Acid |
Abbreviation |
Codons |
---|---|---|
alanine |
Ala |
GCU, GCC, GCA, GCG |
arginine |
Arg |
CGU, CGC, CGA, CGG, AGA, AGG |
asparagine |
Asn |
AAU, AAC |
aspartic acid |
Asp |
GAU, GAC |
cysteine |
Cys |
UGU, UGC |
glutamic acid |
Glu |
GAA, GAG |
glutamine |
Gln |
CAA, CAG |
glycine |
Gly |
GGU, GGC, GGA, GGG |
histidine |
His |
CAU, CAC |
isoleucine |
Ile |
AUU, AUC, AUA |
leucine |
Leu |
UUA, UUG, CUU, CUC, CUA, CUG |
lysine |
Lys |
AAA, AAG |
methionine |
Met |
AUG |
phenylalanine |
Phe |
UUU, UUC |
proline |
Pro |
CCU, CCC, CCA, CCG |
serine |
Ser |
UCU, UCC, UCA, UCG, AGU, AGC |
STOP |
|
UAA, UAG, UGA |
threonine |
Thr |
ACU, ACC, ACA, ACG |
tryptophan |
Trp |
UGG |
tyrosine |
Tyr |
UAU, UAC |
valine |
Val |
GUU, GUC, GUA, GUG |