copyright © 2009 pearson education, inc. chapter 15 lecture concepts of genetics tenth edition gene...

Copyright © 2009 Pearson Education, Inc.

Chapter 15 Lecture

Concepts of GeneticsTenth Edition

Gene Mutation, DNA Repair, and Transposition


What’s a mutation?


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.



Classification Based on Location of Mutation

Somatic, germline, autosomal, X-linked


Mutations are also classified as

dominant versus recessive

“Haploinsufficiency” also is seen.



Classification Based on Phenotypic Effects

Loss-of-functionGain-of-functionMorphologicalNutritionalBehavioralLethalConditional

Copyright © 2009 Pearson Education, Inc. Figure 15.1

Classification Based on Type of Molecular Change

base substitutiontransitiontransversion


15.2 Spontaneous Mutations Arise from Replication Errors and Base Modifications

DNA Replication Errors

Replication Slippage

Tautomeric Shifts


Damage versus mutation



Depurination and Deamination


Deamination



Oxidative Damage

Transposons


15.3 Induced Mutations Arise from DNA Damage Caused by Chemicals and Radiation

Base Analogs



Alkylating Agents and Acridine Dyes


Example of alkylation


crosslinks


Acridine Dyes and Frameshift Mutations

Intercalating agents


A couple of intercalating agents



Ultraviolet Light



Ionizing Radiation


15.4 Single-Gene Mutations Cause a Wide Range of Human Diseases


Section 15.4

Table 15.4


Trinucleotide Repeats in Fragile X Syndrome, Myotonic Dystrophy, and Huntington Disease

“Dynamic mutations”

Genetic anticipation


Cleary and Pearson (2005) Trends in Genetics 21:272-280


15.5 Organisms Use DNA Repair Systems to Counteract Mutations

Proofreading and Mismatch Repair

Postreplication Repair

The SOS Repair System

(SOS Response)


This is not repair!It is an example ofdamage tolerance.


SOS Response

http://www.science.siu.edu/microbiology/micr460/460%20Pages/SOS.html

Pol V is induced andis error-prone.

SOS response in bacteria



Photoreactivation Repair: Reversal of UV Damage



Base and Nucleotide Excision Repair



Nucleotide Excision Repair and Xeroderma Pigmentosum in Humans

Also—defects in pol (eta)



Double-Strand Break Repair in Eukaryotes


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 end-joining, which is error-prone and is prominent during G1.


15.6 The Ames Test Is Used to Assess the Mutagenicity of Compounds


15.7 Geneticists Use Mutations to Identify Genes and Study Gene Function


15.8 Transposable Elements Move within

the Genome and May Create Mutations

Insertion Sequences

Bacterial Transposons


The Ac–Ds System in Maize


Barbara McClintock

Nobel Prize 1983


Breakage-fusion-bridge cycle

www.biologie.uni-hamburg.de/b-online/ge21/18.jpg

Breakage-fusion-bridge cycle


Copia Elements in Drosophila


P Element Transposons in Drosophila

Transposable Elements in Humans


Transposons Create Mutations and Provide Raw Material for Evolution


Transposons Use Two Different Methods to Move Within Genomes

DNA Transposons and Transposition


Transposons Use Two Different Methods to Move Within Genomes

Retrotransposons and Transposition

copyright © 2009 pearson education, inc. chapter 15 lecture concepts of genetics tenth edition gene...

Documents

pearson education

base bonds

anomalous base

new base pairing

bu base pairs

ethylguanine base pairs

b standard base

dna damage