TRANSCRIPTION

TRANSLATION

DNA

mRNARibosome

Polypeptide

(a) Bacterial cell

Nuclearenvelope

TRANSCRIPTION

RNA PROCESSING Pre-mRNA

DNA

mRNA

TRANSLATION Ribosome

Polypeptide

(b) Eukaryotic cell

1

DNAmolecule

Gene 1

Gene 2

Gene 3

DNAtemplatestrand

TRANSCRIPTION

TRANSLATION

mRNA

Protein

Codon

Amino acid2

Second mRNA base

Firs

t mR

NA

base

(5 e

nd o

f cod

on)

Third

mR

NA

base

(3 e

nd o

f cod

on)

3

(a) Tobacco plant expressing a firefly gene

(b) Pig expressing a jellyfish gene

4

Polypeptide

Ribosome

Aminoacids

tRNA withamino acidattached

tRNA

Anticodon

TrpPhe Gly

Codons 35

mRNA5

Amino endof polypeptide

mRNA

5

3E

Psite

Asite

GTP

GDP

E

P A

E

P A

GDPGTP

Ribosome ready fornext aminoacyl tRNA

E

P A

6

Releasefactor

3

5Stop codon(UAG, UAA, or UGA)

5

32

Freepolypeptide

2 GDPGTP

5

3

7

Wild-type hemoglobin DNA

mRNA

Mutant hemoglobin DNA

mRNA

33

3

3

3

3

55

5

55

5

C CT T TTG GA A AA

A A AGG U

Normal hemoglobin Sickle-cell hemoglobinGlu Val

8