genetic code

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genetic code The set of correspondences between base (nucleotide pair) triplets in DNA and amino acids in protein. These base triplets carry the genetic information for protein synthesis. For example, the triplet CAA (cytosine, adenine, adenine) codes for valine. The code is universal, but degenerate, in that certain amino acids are coded for by more than one codon, and the codon bias (the preferred codon for a particular amino acid from the several possible choices) differs somewhat in different organisms and is different in nuclear, mitochondrial, and chlorophyll DNA.

amino acid

abbreviation

codons

alanine

Ala

GCA, GCC, GCG, GCU

arginine

Arg

AGA, AGG, CGA, CGG, CGC, CGU

asparaginine

Asn

AAC, AAU

aspartic acid

Asp

GAC, GAU

cysteine

Cys

UGC, UGU

glutamic acid

Glu

GAA, GAG

glutamine

Gln

CAA, CAG

glycine

Gly

GGA, GGC, GGG, GGU

histidine

His

CAC, CAU

isoleucine

Ile

AUA, AUC, AUU

leucine

Leu

CUA, CUC, CUG, CUU, UUA, UUG

lysine

Lys

AAA, AAG

methionine

Met

AUG

phenylalanine

Phe

UUC, UUU

proline

Pro

CCA, CCC, CCG, CCU

serine

Ser

AGC, AGU, UCA, UCC, UCG, UCU

threonine

Trp

ACA, ACC, ACG, ACU

tryptophan

Trp

UGG

tyrosine

Tyr

UAC, UAU

valine

Val

GUA, GUC, GUG, GUU

stop codon

UAA, UAG, UGA


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