Download Ch. 11.3 Other Patterns of Inheritance Learning Objectives: Describe

Ch. 11.3 Other Patterns of Inheritance
Learning Objectives:


I.
II.
Describe examples of exceptions to Mendel’s principles.
Explain the relationship between genes and the environment.
Complex Patterns of Inheritance
a. Patterns of inheritance that are explained by Mendel’s experiments are often
referred to as _______________.
b. However, many inheritance patterns are more _____________than those studied
by Mendel.
c.
Incomplete dominance: Appearance of a third phenotype
a. When inheritance follows a pattern of__________________, heterozygous and
homozygous dominant individuals both have the same ___________________.
b. When traits are inherited in an ________________________________pattern,
however, the phenotype of heterozygous individuals is _______________
between those of the two homozygotes.
c. Some alleles are neither ______________ nor ____________________.
d. ______________________: One allele is not completely dominant over another.
e. For example, if a homozygous red-flowered snapdragon plant (RR) is crossed
with a homozygous white-flowered snapdragon plant (W W), all of the F1
offspring will have__________________________.
f. The new phenotype occurs because the flowers contain _____________ that
control _______________ production.
g. The ___ allele codes for an enzyme that produces a _____ pigment. The __ allele
codes for a _______________ enzyme that makes __ pigment.
h. Because the heterozygote has only ____ copy of the R allele, its flowers appear
________ because they produce only ________ the amount of red pigment that
red homozygote flowers produce.
i.
III.
IV.
Codominance: Expression of both alleles
a. _______________________cause the phenotypes of both homozygotes to be
produced in heterozygous individuals. In codominance, ______ alleles are
expressed__________________.
b. Examples: chicken feather color, human protein controlling blood cholesterol
levels
i.
ii.
Multiple phenotypes from multiple alleles
a. Although each trait has only ____ alleles in the patterns of heredity you have
studied thus far, it is common for __________________ alleles to control a trait
in a population
b. Traits controlled by more than two alleles have _____________________.
c. Multiple Alleles
i. ________ genes exist in more than _______ forms.
ii. Examples:
1. human blood types,
2. fur color in rabbits
iii.
d. Polygenic Traits
i. Many traits are produced by the _________________ of ___________
genes.
ii. Examples:
1. eye color in fruit flies,
2. coat color in dogs
iii. Traits typically show a _____________________ of _______________.
iv.
e. Polygenic inheritance
i. __________________________ is the inheritance pattern of a trait that is
controlled by __________________________genes.
ii. The genes may be on the _______ chromosome or on ______________
chromosomes, and each gene may have ______________________alleles.
iii. _______________and ________________ letters are used to represent the
alleles.
V.
VI.
iv. However, the allele represented by an uppercase letter ________________
All heterozygotes are______________________ in phenotype.
v. In polygenic inheritance, each allele represented by an uppercase letter
contributes a_______ , but ________, portion to the trait being expressed.
vi. The result is that the phenotypes usually show a _____________________
of variability from the ____________________ value of the trait to the
______________________ value.
Non-Mendelian Inheritance
a. _____________________: influences from DNA of maternal mitochondria and
chloroplasts
b. One example is __________________ in the morning glory (Mirabilis jalapa),
which is determined solely by the color of flower tissue in the maternal parent
c. ______________________________: chemical modification of certain genes
d. A gene regulating body size is imprinted in a way that silences it in the next
generation whenever it is carried by a female. Mice inheriting the gene from their
mothers may suffer from dwarfism. However, mice inheriting the very same gene
from their fathers do not.
Environmental Influences
a. The genetic makeup of an organism at fertilization determines only the
organism’s _____________________ to develop and function.
b. As the organism develops, many ______________ can influence _____ the gene
is expressed, or even ________________ the gene is expressed at all.
c. Two such influences are the organism’s ________________and ______________
environments.
d. ________________________, ____________________, _______________,
____________________, and _______________________________ all can
influence gene expression.
e. In arctic foxes ___________________ has an effect on the expression of coat
color.
i.