9/21/99
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Dr. Wolff
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GeneBiochem
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Summary Notes
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L. Van Warren
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Lecture 1: |
3:1
1:2:1 |
Prequel
For our first session on Tuesday, August
31 please read Chapter 2 "Mendelian Analysis " from "An Introduction
to Genetic Analysis" by A. J. F. Gnffiths et aL, 1996. You should have
received a copy of this chapter as one of the handouts.
Knowledge of the principles of Mendelian
genetics is essential for understanding the nature of health and disease. Individual
organisms are composed of diverse tissues in each of which a network of integrated
cellular processes is controlled and regulated by unique patterns of expressed
genes. "Health" indicates a homeostatic (well-balanced) functioning
of this network. "Disease" reflects dysregulated functioning of some
component(s) of this network. Thus, a disease state indicates that the expression
of one or more genes has been altered qualitatively or quantitatively. This
can be due either to gene mutations or to environmental factors which affect
gene transcription. In either case, such changes in gene expression will alter
one or more physiological parameters; these then are detected as disease symptoms.
In many, if not most, cases, the altered gene expression results in altered
response to environmental stimuli. Thus, the interaction of genetic and environmental
factors is an important consideration in the study and treatment of any disease.
During the next few sessions we will review the basic concepts of Mendelian
genetics which are the basis for the spread of mutations and behavior of genes
in populations of organisms.
To illustrate these concepts we will discuss some specific mutations in the
house mouse in addition to the mutations used in the textbook. The physiologic
(phenotypic) manifestations of these mutations will be used to illustrate their
induction through the effects and interactions of the gene products at the cellular
and tissue levels. This is an example of physiological genomics, which links
the molecular biology of gene function to the physiology and metabolism of the
organism. Physiological genomics seeks to understand/explain how regulation
of gene expression (transcription) affects the regulation of cellular processes
and their interactions in the various body tissues to maintain the homeostatic
(equilibrium) functioning of the whole organism.
George L. Wolff, Ph.D.
8/31/99
Chapter 2 "Mendelian
Analysis "
from "An Introduction to Genetic Analysis" by A. J.
F. Gnffiths et aL, 1996
Introduction
Mendel's Experiments
My choice of material is freshly excised tumors. I want to dissect the tissues into two types, tumor and non-tumor selecting only the cells from which the tumor cells are differentiated.
Plants Differing in One Character
Character
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Phenotypes
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flower color
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purple vs. white
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flower purpleness
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presence vs. absence
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flower whiteness
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presence vs. absence
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cross(phenotypeA-male, phenotypeB-female)
cross(phenotypeB-male, phenotypeA-female)
Plants Differing in Two Characters
AB
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Ab
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aB
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AB
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AB
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AABB
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AABb
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AaBB
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AaBb
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AB
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AAbB
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AAbb
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AabB
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Aabb
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AB
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aABB
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aABb
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aaBB
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aaBb
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AB
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aAbB
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aAbb
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aabB
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abbb
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Meddle's Second Law of Independent Assortment
During gamete formation the segregation of alleles of one gene is independent
of the segregation of the alleles of another gene (PROVIDED
THE GENES ARE ON SEPARATE CHROMOSOMES OR ARE FAR APART ON THE SAME CHROMOSOME!)
Simple Mendelian Genetics in Humans