Chapter 11 Section 3 Notes
11-3 Exploring Mendelian Genetics
Name: ___________________________________ Date: _______________
Period: _____
Objectives:
 Explain the principle of independent assortment.
 Describe the inheritance patterns that exist aside from simple dominance.
 Explain how Mendel’s principles apply to all organisms.
Independent Assortment:
 Mendel performed an experiment to follow __________ different _______________ as they
passed from one _____________________ to the ____________.
 Mendel’s experiment is known as a _______ - _______________ ______________.
The Two-Factor Cross: F1:
 First, Mendel crossed ___________-_____________ plants that produced only round yellow
peas (genotype RRYY) with plants that produced wrinkled green peas (genotype rryy).
 All of the F1 offspring produced round yellow peas.
 This shows that the alleles for yellow and round peas are ________________ over the alleles for
green and wrinkled.
F1:
 How is the genotype of the offspring different from that of the homozygous dominant parent?
The Two-Factor Cross: F2:
 The F1 plants were all _______________________for both the seed shape and seed color genes.
 The F1 plants were _________________ to each other to produce an F2 generation.
 Findings:
 315 out of 556 were ________________ and _______________
 32 out of 556 were __________________ and _________________
 209 out of 556 had _______________________ of phenotypes
 Conclusion:
 This clearly meant that the alleles for seed shape ______________________
independently of those for seed color – a principle known as ______________________
__________________________.
F2:
Principle of Independent Assortment:
 The principle of independent assortment states that genes for __________________ traits can
segregate ____________________during the formation of _________________.
 Independent assortment ___________ account for the many genetic ________________
observed in plants, _______________, and other organisms.
A Summary of Mendel’s Principles:
 The __________________ of biological ____________________ is determined by individual
units known as ________________. Genes are passed form _________________ to their
_________________.
 In cases in which two or more forms (__________________) of the gene for a single trait exist,
some forms of the gene may be _____________________ and other may be _______________.
 In most sexually reproducing organisms, each adult has _____________ copies of each
_____________ – one from each ______________. These genes are ___________________
from each other when ____________________ are formed.
 The ____________________ for different __________________ usually segregate
_________________________ of each other.
Beyond Dominant and Recessive Alleles:
 Exceptions to Mendel’s work:

Not __________ genes show simple patterns of ________________ and
____________________ alleles.
 Some alleles are ________________ dominant nor recessive, and many traits are
controlled by multiple ______________ or multiple ________________.
Incomplete Dominance:
 Example:
 Cross between two four o’clock (Mirabilis)
 The F1 generation produced by a cross between ________-flowered (RR) and
_______________-flowered (WW) plants consists of ___________-colored
flowers (RW).
 Cases in which one allele is not ____________________ dominant over another is called
_____________________ dominance.
 In incomplete dominance, the heterozygous phenotype is somewhere _____________________
the two homozygous phenotypes.
Codominance:
 Codominance is when _______________ alleles contribute to the ____________________.
Multiple Alleles:
 Many genes have more than ____________ alleles and are therefore said to have multiple
alleles.
Polygenic Traits:
 Traits controlled by ____________ or more genes are said to be polygenic traits, which means
“having many ______________”.
 Polygenic traits often show a wide range of ______________________.
 For example, the wide range of skin color in _______________ comes about partly because
more than four different ______________ probably control that trait.
Applying Mendel’s Principles:
 Mendel’s principles also apply to ________________.
 The basic principles of Mendelian genetics can be used to study the inheritance of human
__________________ and to calculate the _______________ of certain traits appearing in the
next generation.
Genetics and the Environment:
 The characteristics of any organism, whether bacterium, fruit fly, or human being, are
_______________ determined solely by the ______________ it inherits.
 Characteristics are determined by ____________________ between ______________ and the
____________________________.