RNA ProteinDNA

Replication Transcription Translation

Polymerase

Monomers

DNA Pol III (and I)

dNTPs

Direction of synthesis

5’ to 3’

Template ssDNA

Product polynucleotide

RNA ProteinDNA

Replication Transcription Translation

Polymerase

Monomers

DNA Pol III (and I)

RNA Pol

dNTPs NTPs

Direction of synthesis

5’ to 3’ 5’ to 3’

Template ssDNA ssDNA

Product polynucleotide polynucleotide

Fig. 17-7a-1Promoter Transcription unit

DNAStart pointRNA polymerase

553

3

Fig. 17-7a-2Promoter Transcription unit

DNAStart pointRNA polymerase

553

3

Initiation

33

1

RNAtranscript

5 5

UnwoundDNA

Template strandof DNA

Fig. 17-7a-3Promoter Transcription unit

DNAStart pointRNA polymerase

553

3

Initiation

33

1

RNAtranscript

5 5

UnwoundDNA

Template strandof DNA

2 Elongation

RewoundDNA

5

5 5 3 3 3

RNAtranscript

Fig. 17-7a-4Promoter Transcription unit

DNAStart pointRNA polymerase

553

3

Initiation

33

1

RNAtranscript

5 5

UnwoundDNA

Template strandof DNA

2 Elongation

RewoundDNA

5

5 5 3 3 3

RNAtranscript

3 Termination

5

5 5 33

3Completed RNA transcript

Fig. 17-7b

Elongation

RNApolymerase

Nontemplatestrand of DNA

RNA nucleotides

3' end

Direction oftranscription(“downstream”) Template

strand of DNANewly madeRNA

3'

5'

5'

RNA ProteinDNA

Replication Transcription Translation

Polymerase

Monomers

DNA Pol III (and I)

RNA Pol

dNTPs NTPs

Direction of synthesis

5’ to 3’ 5’ to 3’

Template ssDNA ssDNA

Product polynucleotide polynucleotide

Fig. 17-5Second mRNA base

Firs

t mRN

A ba

se (5

end

of c

odon

)

Third

mRN

A ba

se (3

end

of c

odon

)

Polypeptide

Ribosome

Aminoacids

tRNA withamino acidattached

tRNA

Anticodon

Trp

Phe Gly

Codons 35

mRNA

the mechanism of translation

Fig. 17-14

Amino acidattachment site

3

5

Hydrogenbonds

Anticodon

(a) Two-dimensional structure

Amino acidattachment site

53

Hydrogenbonds

3 5AnticodonAnticodon

(c) Symbol used in this book(b) Three-dimensional structure

Amino acid Aminoacyl-tRNAsynthetase (enzyme)

ATP

AdenosineP P P

AdenosineP

PP i

PPi

i

tRNA

tRNA

Aminoacyl-tRNAsynthetase

Computer modelAMPAdenosineP

Aminoacyl-tRNA(“charged tRNA”)

Attaching amino acids to tRNAs:Amino-acyl tRNA synthases

-20 different synthases-Require ATP-Each must be specific to the right amino acid and tRNA(s)

tRNAGLN

Aminoacyl-tRNA synthase(ATSGLN)

Adenylated Glutamine

Fig. 17-16bP site (Peptidyl-tRNAbinding site) A site (Aminoacyl-

tRNA binding site)E site(Exit site)

mRNAbinding site

Largesubunit

Smallsubunit

(b) Schematic model showing binding sites

Next amino acidto be added topolypeptide chain

Amino end Growing polypeptide

mRNAtRNA

E P A

E

Codons

(c) Schematic model with mRNA and tRNA

5

3

The Ribosome

LSU

SSU

Fig. 17-18-1

Amino endof polypeptide

mRNA

5

3E

Psite

Asite

Fig. 17-18-2

Amino endof polypeptide

mRNA

5

3E

Psite

Asite

GTP

GDP

E

P A

Fig. 17-18-3

Amino endof polypeptide

mRNA

5

3E

Psite

Asite

GTP

GDP

E

P A

E

P A

Peptide bond formation- Transfer of growing chain from tRNA in P site to tRNA in A site

Fig. 17-18-3

Amino endof polypeptide

mRNA

5

3E

Psite

Asite

GTP

GDP

E

P A

E

P A

Fig. 17-18-4

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

Fig. 17-17

3355U

UA

ACGMet

GTP GDPInitiator

tRNA

mRNA5 3

Start codon

mRNA binding siteSmallribosomalsubunit

5

P site

Translation initiation complex

3

E A

Met

Largeribosomalsubunit

Initiating translation

Fig. 17-19-1

Releasefactor

3

5Stop codon(UAG, UAA, or UGA)

Terminating translation

Fig. 17-19-2

Releasefactor

3

5Stop codon(UAG, UAA, or UGA)

5

32

Freepolypeptide

2 GDP

GTP

Terminating translation

Fig. 17-19-3

Releasefactor

3

5Stop codon(UAG, UAA, or UGA)

5

32

Freepolypeptide

2 GDP

GTP

5

3

Terminating translation

Fig. 17-20

Growingpolypeptides

Completedpolypeptide

Incomingribosomalsubunits

Start ofmRNA(5 end)

PolyribosomeEnd ofmRNA(3 end)

(a)

Ribosomes

mRNA

(b) 0.1 µm

Fig. 17-24RNA polymerase

DNA

Polyribosome

mRNA

0.25 µmDirection oftranscription

DNA

RNApolymerase

Polyribosome

Polypeptide(amino end)

Ribosome

mRNA (5 end)

In bacteria:Translation can happen while transcription is still ocurring

Fig. 18-3a

Polypeptide subunits that make upenzymes for tryptophan synthesis

mRNA 5

Promoter

trp operon

Genes of operon

Stop codonStart codon

trpAtrpE trpD trpC trpB

ABCDE

In bacteria: Many genes are organized in operons

Operon = group of genes sharing one promoter, expressed as 1 mRNAs containing multiple ORFs

RNA ProteinDNA

Replication Transcription Translation

Polymerase

Monomers

DNA Pol III (and I)

RNA Pol

dNTPs NTPs

Direction of synthesis

5’ to 3’ 5’ to 3’

Template ssDNA ssDNA

Product polynucleotide polynucleotide

ribosome

Aminoacyl-tRNAs

mRNA

N to C

polypeptide