Transcript Klug10chapt15

Chapter 15 Lecture
Concepts of Genetics
Tenth Edition
Gene Mutation, DNA
Repair, and
Transposition
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What’s a mutation?
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15.1 Mutations Are Classified in
Various Ways
Spontaneous and Induced Mutations
The Luria-Delbruck Fluctuation Test:
Are Mutations Spontaneous or
Adaptive?
Hypothesis 1: Adaptive Mutation.
Hypothesis 2: Spontaneous
Mutation.
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Table 15.2
15.1 Mutations Are Classified in Various
Ways
Classification Based on Location of Mutation
Somatic, germline, autosomal, X-linked
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Mutations are also classified as
dominant versus recessive
“Haploinsufficiency” also is seen.
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15.1 Mutations Are Classified in Various
Ways
Classification Based on Phenotypic Effects
Loss-of-function
Gain-of-function
Morphological
Nutritional
Behavioral
Lethal
Conditional
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Classification Based on Type of Molecular Change
base substitution
transition
transversion
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Figure 15.1
15.2 Spontaneous Mutations Arise from
Replication Errors and Base
Modifications
DNA Replication Errors
Replication Slippage
Tautomeric Shifts
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Figure 15.2
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Figure 15.2a
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Figure 15.2b
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Figure 15.3
Damage versus mutation
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15.2
Spontaneous Mutations Arise from
Replication Errors and Base
Modifications
Depurination and Deamination
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Deamination
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Figure 15.4
15.2 Spontaneous Mutations Arise from
Replication Errors and Base
Modifications
Oxidative Damage
Transposons
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15.3
Induced Mutations Arise from DNA
Damage Caused by Chemicals and
Radiation
Base Analogs
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Figure 15.5
15.3
Induced Mutations Arise from DNA
Damage Caused by Chemicals and
Radiation
Alkylating Agents and Acridine Dyes
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Example of alkylation
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Figure 15.6
crosslinks
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Acridine Dyes and Frameshift
Mutations
Intercalating agents
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A couple of intercalating agents
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15.3 Induced Mutations Arise from DNA
Damage Caused by Chemicals and
Radiation
Ultraviolet Light
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Figure 15.7
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Figure 15.8
15.3
Induced Mutations Arise from DNA
Damage Caused by Chemicals and
Radiation
Ionizing Radiation
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Figure 15.9
15.4 Single-Gene Mutations Cause a
Wide Range of Human Diseases
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Table 15.3
Section 15.4
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Table 15.4
Trinucleotide Repeats in Fragile X
Syndrome, Myotonic Dystrophy, and
Huntington Disease
“Dynamic mutations”
Genetic anticipation
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Table 15-4
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Cleary and Pearson (2005) Trends in Genetics 21:272-280
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15.5 Organisms Use DNA Repair Systems
to Counteract Mutations
Proofreading and Mismatch Repair
Postreplication Repair
The SOS Repair System
(SOS Response)
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This is not repair!
It is an example of
damage tolerance.
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Figure 15.11
Response
SOSSOS
response
in bacteria
Pol V is induced and
is error-prone.
http://www.science.siu.edu/microbiology/micr460/460%20Pages/SOS.html
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15.5 Organisms Use DNA Repair Systems
to Counteract Mutations
Photoreactivation Repair: Reversal of UV Damage
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Figure 15.12
15.5
Organisms Use DNA Repair Systems
to Counteract Mutations
Base and Nucleotide Excision Repair
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Figure 15.13
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Figure 15.14
15.5 Organisms Use DNA Repair Systems
to Counteract Mutations
Nucleotide Excision Repair and Xeroderma
Pigmentosum in Humans
Also—defects in pol  (eta)
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Figure 15.15
15.5 Organisms Use DNA Repair Systems
to Counteract Mutations
Double-Strand Break Repair in Eukaryotes
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There are other pathways for
DSB repair via homologous
recombination.
This type of repair is
accurate, and is prominent in
late S/G2 .
DSBs can also be repaired
via nonhomologous endjoining, which is error-prone
and is prominent during G1.
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Figure 15.16
15.6 The Ames Test Is Used to Assess the
Mutagenicity of Compounds
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Figure 15.17
15.7 Geneticists Use Mutations to Identify
Genes and Study Gene Function
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15.8 Transposable Elements Move within
the Genome and May Create Mutations
Insertion Sequences
Bacterial Transposons
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Figure 15.18
The Ac–Ds System in Maize
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Barbara McClintock
Nobel Prize 1983
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Figure 15.19
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Figure 15.19a
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Figure 15.19b
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Figure 15.19c
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Breakage-fusion-bridge cyclecycle
Breakage-fusion-bridge
www.biologie.uni-hamburg.de/b-online/ge21/18.jpg
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Copia Elements in Drosophila
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Figure 15.20
P Element Transposons in Drosophila
Transposable Elements in Humans
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Transposons Create Mutations and
Provide Raw Material for Evolution
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Table 22.1
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Transposons Use Two Different
Methods to Move Within Genomes
DNA Transposons and Transposition
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Transposons Use Two Different
Methods to Move Within Genomes
Retrotransposons and Transposition
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