Organic Chemistry

Section 27.13 Biosynthesis of Proteins: Translation 055

confuse transcription and translation—these words are used just as they are used in
English. Transcription (DNA to RNA) is copying within the same languageof
nucleotides. Translation (RNA to protein) is changing to another language—the lan-
guage of amino acids.
How the information in mRNA is translated into a polypeptide is shown in
Figure 27.16. In this figure, serine was the last amino acid incorporated into the

codon

anticodon

tRNA

mRNA

growing

polypeptide

chain

tRNA that

had carried

serine

the ester and the primary

amino groups engage in

a nucleophilic acyl

substitution reaction

leucine

codes for

alanine

serine

G A A G A A

5 ′ AUG C CCU G C 3 ′

C G G

U C G

5 ′ AUG C CCU GCC GCU CAC G A 3 ′

RO

NH CH C

RO

O

ACC

O

NH CH C NH

CH 2

OH

CH C

GAA A G A

=

O

ACC

O

H 2 N

CH 2

CH 3

CH CH 3

CH C

U C G

5 ′ AUG C CCU G C 3 ′

RO

NH CH C

RO

O

ACC

O

NH CH C NH

CH 2

OH

CH C

G A A

O

ACC

O

H 2 N

CH 2

CH 3

CH CH 3

CH C

RO

NH CH C

RO

O

O

NH CH C

O

NH C

CH 2

OH

CH NH

CH 2

CH

CH C

O

ACC

ACC

OH

ACC

O

H 2 N

CH (^3) CH 3
CH 3
CH C

Figure 27.16
Translation. The sequence of bases
in mRNA determines the sequence
of amino acids in a protein.
Transcription: DNA¡RNA
Translation: mRNA¡protein
Tutorial:
Translation