Mutaciones geneticas

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10/4/2009

William S. Klug• Michael R. Cummings • Charlotte A. Spencer

Essentials of Genetics
Sixth Edition
Chapter 14. Part 1: Genetic Mutations and DNA Repair

Copyright © 2009 byPearson/Prentice Hill

Introduction

OPENING STORY

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Part 01

SOURCE OF THE GENETIC VARIABILITY REQUIRED FOR EVOLUTION

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Mutations
• Mutation– A change in the genetic material – The process by which the change occurs

• Mutant—an organism that exhibits a novel phenotype • Types of Mutations
– Changes in chromosome number and structure– Point mutations—changes at specific sites in a gene (substitution, insertion, or deletion)

Somatic or germinal
• Somatic mutations -- occur in somatic cells; the mutant phenotype will occur onlyin the descendants of that cell and will not be transmitted to the progeny • Germinal (or germ-line) mutations -- occur in germ-line cells and will be transmitted through the gametes to the progeny4

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Spontaneous or induced
• Spontaneous mutations -occur without a known cause due to inherent metabolic errors or unknown agents in the environment • Induced mutations -- result fromexposure or organisms to mutagens, physical and chemical agents that cause changes in DNA, such as ionizing irradiation, ultraviolet light, or certain chemicals

Back mutation and supressormutation

Classification based on molecular change

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Frameshift mutations

Classification based on location of mutation

autosomal

X-linked

Classification based on phenotypiceffect: morphological

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Classification based on phenotypic effect: biochemical

Classification based on phenotypic effect: nutritional

Prototrophy vs. auxotrophy

Mutationfrequency
• Spontaneous mutations are infrequent
– Bacteria and phage: 10–8 to 10–10 per nucleotide pair per generation – Eukaryotes: 10–7 to 10–9 per nucleotide pair per generation, or 10–4 to...
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