Translation
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yright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Translation mRNA is translated in codons (three nucleotides) Translation of mRNA begins at the start codon: AUG Translation ends at a stop codon: UAA, UAG, UGA PLAY Animation: Translation Figure 8.2
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Translation. mRNA is translated in codons (three nucleotides) Translation of mRNA begins at the start codon: AUG Translation ends at a stop codon: UAA, UAG, UGA. PLAY. Animation: Translation. Figure 8.2. Translation. Figure 8.10. Translation. Figure 8.9, step 1. Translation. - PowerPoint PPT Presentation
Transcript of Translation
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Translation
mRNA is translated in
codons (three nucleotides)
Translation of mRNA
begins at the start codon:
AUG
Translation ends at a stop
codon: UAA, UAG, UGA
PLAY Animation: Translation
Figure 8.2
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Translation
Figure 8.10
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Translation
Figure 8.9, step 1
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Translation
Figure 8.9, step 2
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Translation
Figure 8.9, step 4
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Translation
Figure 8.9, step 6
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Translation
Figure 8.9, step 8
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Regulation of Bacterial Gene Expression
Constitutive enzymes are expressed at a fixed rate.
Other enzymes are expressed only as needed.
Repressible enzymes
Inducible enzymes
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Operon
PLAY Animation: Operons
Figure 8.12, step 1
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Enzyme Induction
Figure 8.12, step 2a
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Enzyme Induction
Figure 8.12, step 3a
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Enzyme Repression
Figure 8.12, step 2b
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Enzyme Repression
Figure 8.12, step 3b
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Regulation of Gene Expression
Figure 8.13
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Mutations
A change in the DNA - genetic material
Mutations may be neutral, beneficial, or harmful.
Mutagen: Agent that causes mutations
Spontaneous mutations: Occur in the absence of a
mutagen
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Mutation
Base substitution
(point mutation)
Missense
mutation
Change in one
base
Result in change
in amino acid
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Mutation
Nonsense mutation
Results in a nonsense codon
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Mutation
Frameshift mutation
Insertion or deletion of one or more nucleotide
pairs
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Mutation
Ionizing radiation (X rays and gamma rays) causes the
formation of ions that can react with nucleotides and
the deoxyribose-phosphate backbone.
Nucleotide excision repairs mutations.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Mutation
UV radiation causes thymine dimers.
Light-repair separates thymine dimers.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
The Frequency of Mutation
Spontaneous mutation rate = 1 in 109 replicated base
pairs or 1 in 106 replicated genes
Mutagens increase to 10–5 or 10–3 per replicated gene.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Selection
Positive (direct) selection detects mutant cells because
they grow or appear different.
Negative (indirect) selection detects mutant cells
because they do not grow.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Replica Plating
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
The Ames Test for Chemical Carcinogens
![]project-translation[ Innovation in Translation Processes](https://static.fdocuments.in/doc/165x107/54b32a654a7959461f8b45fd/project-translation-innovation-in-translation-processes.jpg)
