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Unformatted text preview: cats. Ex. Leaf shape in the water buttercup (Ranunculus
aquatilis). Ex. Color in hydrangea flowers. Epistasis / Gene x Gene Interactions
- Interactions can occur between genes at different loci.
- Epistasis = when phenotype produced by an allele depends on actions of genes at other
Ex. Fruit color in Bell Peppers
Gene 1 (red pigment)
R = Red
r = Yellow
R -Y rrYR-yy
rryy Gene 2 (chlorophyll prod.)
Y = Absence of green
y = Presence of green
Green wheat tha
suits of a
Ehle prop (b) Crosses between pure lines produce novel colors.
generation x The pa
and aa Brown Yellow • The th
1/4 X 1
3/16 (c) Model to explain 9 : 3 : 3: 1 pattern observed above:
Two genes interact to produce pepper color. Green
1/16 • The a,
amount Ex. Coat color of Labrador retrievers
Gene 1 (melanin production):
Gene 2 (melanin deposition in hair): E, e
B -E bbE--ee Phenotype
Yellow Polygenic Inheritance
- Each locus contributes small amount to phenotype.
- Produces “Quantitative Trait” - range of phenotypes.
- Continuous, bell-shaped (normal) distribution of
phenotypes in population.
- Opposite to “Discrete Traits”. Ex. Kernel color in wheat
3 independent genes control degree of red pigmentation
white AaBbCc AABBCC
deep red Ex. Human height, weight, and skin color...
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This note was uploaded on 02/24/2014 for the course BIOL 180 taught by Professor Freeman during the Winter '07 term at University of Washington.
- Winter '07