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BIOLOGY 207 - Dr.McDermid Lecture#8 : Classification of mutations and gene function Readings: Griffiths et al, 7th Edition: Ch. 15 pp 467-472 Problems: none Concepts: How do DNA mutations affect the organism? 1. the tissue where they occur 2. the system that they affect 3. molecular changes to the gene product Somatic vs Germline mutations Somatic cells - from the tissues of the organism Germline cells - those that form the germ cells 1) Somatic Mutations - a mutant cell, and its descendants, will form a clone - Somatic mutations only produce an affect (phenotype) in the individual in which they occur -> mosaic Lecture# 10 Page 1 Mosaic - an individual composed of two (or more) types (lines) of cells that differ in their genetic composition 2) Germline (germinal) Mutations - occur in the sex cells or cells that lead to sex cells - Animals -> segregate these cells from somatic cells - Plants -> somatic cells become germ cells General classification of germline mutants 1) Morphological mutations - change in the form of the organism. 2) Lethal mutations - mutation that leads to or causes death of an organism 3) Conditional mutations Genotype + Environment + Interaction = Phenotype Lecture# 10 Page 2 Restrictive conditions Permissive conditions 4) Biochemical mutations - produce auxotrophic mutants from prototrophic parents Muller's morphs - (1932) Amorph - A- absence - mutation with complete absence of wild type function Hypomorph - hypo -> less than -> less than wild type level of expression of the wild type gene - same quality Lecture# 10 Page 3 Hypermorph - hyper -> more than -> more than wild type level of gene expression Neomorph - neo -> new - mutations which create a new and different from the wild type function for the gene Lecture# 10 Page 4 Antimorph - anti -> against - mutant gene product results in a reduction or loss in the function and interferes with normal gene product from any wild type gene that may be present Summary There are various different schemes for classifying mutations They describe mutations at different levels ______________________________________________________________________________________________ Lecture notes: Copyright © 2002 Heather McDermid and the Department of Biological Sciences, University of Alberta Images are Copyright©2000 by W.H. Freeman & Co. in Griffiths et al, Introduction to Genetic Analysis Lecture# 10 Page 5
