chapter 17: from gene to protein. figure 17-01 le 17-2 class i mutants (mutation in gene a) wild...
Post on 18-Jan-2018
223 Views
Preview:
DESCRIPTION
TRANSCRIPT
Chapter 17:From Gene to Protein
Figure 17-01
LE 17-2
Class IMutants(mutationIn gene A)Wild type
Class IIMutants(mutationIn gene B)
Class IIIMutants(mutationIn gene C)
Precursor
Ornithine
AEnzyme
A
Citrulline
Arginine
Gene A
Gene B
Gene C
Precursor Precursor Precursor
AA
B B B
Ornithine Ornithine OrnithineEnzyme
B
EnzymeC
Arginine Arginine ArginineC C C
Citrulline Citrulline Citrulline
MinimalMedium(MM)(control)
Wild typeClass IMutants
Class IIMutants
Class IIIMutants
MM +Ornithine
MM +Citrulline
MM +arginine(control)
LE 17-4
DNAmolecule
Gene 1
Gene 2
Gene 3
DNA strand(template)
3
TRANSCRIPTION
Codon
mRNA
TRANSLATION
Protein
Amino acid
35
5
DNA vs. RNA(review from chapter 5)
Activity: (16) DNA and RNA Structure
LE 17-3-2
TRANSCRIPTIONDNA
Prokaryotic cellRibosome
Polypeptide
mRNA
Prokaryotic cell
Activity: Overview of Protein Synthesis
20 amino acids
LE 17-5Second mRNA base
Firs
t mR
NA
bas
e (5
end
)
Third
mR
NA
bas
e (3
end
)
LE 17-7
Elongation Non-templatestrand of DNA
RNApolymerase
RNA nucleotides
3 end3
5
5
Newly madeRNA
Templatestrand of DNA
Direction of transcription(“downstream”)
Promoter
53
RNA polymeraseStart point
DNA
Transcription unit
35
53
35
UnwoundDNA
RNAtran-script
Template strandof DNA
Initiation
Elongation
Termination
53
35
53
35
35
RewoundDNA
RNAtranscript
5
Completed RNA transcript
Activity: Transcription
Transcription
LE 17-7a-1
Promoter Transcription unit
RNA polymeraseStart point DNA
53
35
LE 17-9
5Protein-coding segment
5 Start codon Stop codon Poly-A tail
Polyadenylation signal
5 3Cap UTR UTR
Activity: RNA Processing
mRNA processing (eukaryotes only)
LE 17-10
5 Exon Intron Exon Intron Exon 3Pre-mRNA
1 30 31 104 105 146
Codingsegment
Introns cut out andexons spliced together
1 1465Cap
5Cap
Poly-A tail
Poly-A tail
5 3UTR UTR
LE 17-11
Exon 15
Intron Exon 2
Other proteinsProtein
snRNA
snRNPs
RNA transcript (pre-mRNA)
Spliceosome
5
Spliceosomecomponents
Cut-outintron
mRNA
Exon 1 Exon 25
LE 17-12
Gene
Transcription
RNA processing
Translation
Domain 2
Domain 3
Domain 1
Polypeptide
Exon 1 Intron Exon 2 Intron Exon 3
DNA
Activity: Overview of Protein Synthesis
Protein Synthesis
Polypeptide
tRNA withamino acidattached
Ribosome
tRNA
Anticodon
35
mRNA
Aminoacids
Codons
LE 17-14a
Amino acidattachment site
Hydrogenbonds
3
5
Two-dimensional structureAnticodon
Amino acidattachment site
35
Hydrogenbonds
Anticodon Anticodon
Symbol used in this bookThree-dimensional structure
3 5
tRNA
LE 17-15Amino acid Aminoacyl-tRNA
synthetase (enzyme)
Pyrophosphate
Phosphates
tRNA
AMP
Aminoacyl tRNA(an “activatedamino acid”)
LE 17-16
Amino end
mRNA
5
3
Growing polypeptide
Next amino acidto be added topolypeptide chain
tRNA
Schematic model with mRNA and tRNA
Computer model of functioning ribosome
5 3
E
Codons
Schematic model showing binding sites
Smallsubunit
Largesubunit
A site (Aminoacyl-tRNA binding site)E site
(Exit site)E P A
mRNAbinding site
P site (Peptidyl-tRNAbinding site)
Smallsubunit
Largesubunit
Exit tunnelGrowingpolypeptidetRNA
molecules
E P A
mRNA
Activity: Translation
LE 17-17
Met
GTPInitiator tRNA
mRNA
5 3
mRNA binding site
Smallribosomalsubunit
Start codon
P site
5 3
Translation initiation complex
E A
Largeribosomalsubunit
GDP
Met
Translation: Initiation
LE 17-18
Ribosome ready fornext aminoacyl tRNA
mRNA
5
Amino endof polypeptide
E
Psite
Asite
3
2
2 GDP
E
P A
GTP
GTP
GDP
E
P A
E
P A
Elongation
LE 17-5Second mRNA base
Firs
t mR
NA
bas
e (5
end
)
Third
mR
NA
bas
e (3
end
)
LE 17-19
Releasefactor
Stop codon(UAG, UAA, or UGA)
5
3
5
3
5
Freepolypeptide
3
When a ribosome reaches a stopcodon on mRNA, the A site of theribosome accepts a protein calleda release factor instead of tRNA.
The release factor hydrolyzes thebond between the tRNA in theP site and the last amino acid of thepolypeptide chain. The polypeptideis thus freed from the ribosome.
The two ribosomal subunitsand the other componentsof the assembly dissociate.
Termination
DNAi.org
LE 17-20
Ribosomes
mRNA
This micrograph shows a large polyribosome in a prokaryotic cell (TEM).
An mRNA molecule is generally translated simultaneouslyby several ribosomes in clusters called polyribosomes.
Incomingribosomalsubunits
Growingpolypeptides
End ofmRNA(3 end)
Start ofmRNA(5 end)
Polyribosome
Completedpolypeptides
m0.1
LE 17-21
Ribosomes
mRNASignalpeptide
Signal-recognitionparticle(SRP)
SRPreceptorprotein
CYTOSOL
ER LUMEN Translocationcomplex
Signalpeptideremoved
ERmembrane
Protein
LE 17-22
RNA polymerase
DNA
Polyribosome
RNApolymerase
Direction oftranscription
mRNA
0.25
DNA
Polyribosome
Polypeptide(amino end)
Ribosome
mRNA (5 end)
m
LE 17-23
Wild-type hemoglobin DNA
mRNA
3 5 53
5 3 35
Mutant hemoglobin DNA
mRNA
Normal hemoglobin Sickle-cell hemoglobin
LE 17-24
Base-pair substitution
No effect on amino acid sequenceU instead of C
MissenseA instead of G
NonsenseU instead of A
Stop
Amino end
Protein5 3
Carboxyl end
Stop
Stop
Stop
mRNA
Wild type
LE 17-25
Base-pair insertion or deletion
Frameshift causing immediate nonsense
Extra U
MissingFrameshift causingextensive missense
Insertion or deletion of 3 nucleotides:no frameshift but extra or missing amino acid
Missing
Stop
Stop
Amino end Carboxyl endStop
Wild type
mRNAProtein
5 3
LE 17-26
TRANSCRIPTION
RNA PROCESSING
RNAtranscript5
Exon
NUCLEUS
FORMATION OFINITIATION COMPLEX
CYTOPLASM
3
DNA
RNApolymerase
RNA transcript(pre-mRNA)
Intron
Aminoacyl-tRNAsynthetase
AminoacidtRNA
AMINO ACID ACTIVATION
3
mRNA
A
P
E Ribosomalsubunits
5
Growingpolypeptide
E A
Activatedamino acid
Anticodon
TRANSLATION
Codon
Ribosome
Noncoding segments…
Follow up to the Unseen Genome: Gems Among the Junk
ENCODE
top related