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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
5
3
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. 17-16b
P 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. 17-24
RNA 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