Book Definitions and Messages

Book Definitions - Book Definitions and Messages*Does not include definitions given in class Chapter 1 1.6 Genes the Environment and the Organism

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Book Definitions and Messages *Does not include definitions given in class.* Chapter 1 1.6: Genes, the Environment, and the Organism. Genotype As an organism transforms developmentally from one stage to another, its genes interact with its environment at each moment of its life history. The interaction of genes and environment determines what organisms are. o Model I: Genetic Determination o Model II: Environmental Determination o Model III: Genotype-environment interaction When we use the terms phenotype and genotype, we generally mean “partial phenotype” and “partial genotype” and we specify one or a few traits and genes that are the subsets of interest. o This is because phenotypes and genotypes always vary at least a little bit. o Genotypes remain constant, but phenotypes continually change. Developmental noise In some characteristics, such as eye cells in Drosophila, developmental noise is a major source of observed variations in phenotype. o Eye facets in Drosophila melanogaster. Chapter 2 Introduction Gene discovery: Find the subset of genes in the genome that influence that property. Single-gene inheritance: The detection of this is one of the most widely used analytical approaches to genetic discovery. Crosses: Controlled matings. Mutants: Individual organisms having some altered form of a normal property.
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Wild Type: Normal form of any property of an organism that is found in nature. Genetic Modus Operandi: Mate an individual showing the property in its wild- type form (for example, a plant with red flowers) to an individual showing a mutated form of the property (for example, a plant with white flowers). The progeny are interbred, and, in their progeny, the ratio of plants with red flowers to those with white flowers will reveal whether a single gene controls that difference in the property under study. Genetic dissection: The biological property in question (flower color in this case) is picked apart to reveal its underlying genetic program not with a scalpel but with mutants. Each mutant potentially identifies a separate gene affecting that property. Screen: The most direct way to obtain mutants is by screening a very large number of individuals, looking for a chance occurrence of mutants in that population. Arabidopsis thaliana: Effects of mutants on flower development. o Number or type of floral organs is altered. Neurospora crassa: Development of the mycelium. o Growth rate and number of branches are altered in a variety of ways. Single gene: Each individual case must be tested to see if it produces descendents in the appropriate ratio. The genetic approach to understanding a biological property is to discover the genes that control it. One approach to genetic discovery is to isolate mutants and check each one for single-gene inheritance patterns (specific ratios of normal and mutant expression of the property in descendants). Gregor Mendel
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This note was uploaded on 09/10/2009 for the course BIO 73678 taught by Professor Pierson during the Spring '09 term at University of Texas at Austin.

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Book Definitions - Book Definitions and Messages*Does not include definitions given in class Chapter 1 1.6 Genes the Environment and the Organism

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