Download Answers PDP Chapter 11.3

Name: ____________________________________
Title of Text: Ch. 11.3—Exploring Mendelian Genetics
PreDuringPost Cornell Notes
Essential Question(s):
How does biological information pass from one generation to another?
How can we use genetics to study human inheritance?
Prediction: I predict this section will be about Mendelian genetics, which may have something to do with genetic crosses.
Questions
1. What is independent assortment?
Answers
Mendel wanted to know if the alleles
segregated with respect to one another or if
they separated independent of one another.
a. How do you perform a two factor cross
with the F1 generation? [See lecture
notes for actual cross method]
Mendel crossed true-breeding plants with two
dominant traits with true-breeding plants with
two recessive traits.
o Step 1: segregate the alleles of each
parent genotype to determine the
gametes (use FOIL or a Punnett
square)
o Step 2: place gamete genotypes in
dihybrid cross and determine all
possible offspring.
b. How do you perform a two factor cross
with the F2 generation?
He then crossed the F1 generation to produce
the F2 generation, in which independent
assortment was observed. (See above for
method; replaced genotypes with that of F1
generation.
The principle of independent assortment sates
that genes for different traits can segregate
independently during the formation of
gametes. Independent assortment helps
account for the many genetic variations
observed in plants, animals and other
organisms.
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J.Adams/AEC/2010
PDP Cornell Notes
Questions
Answers
2. How can Mendel’s principles be summarized?
Mendel’s “factors” responsible for heredity
are known as genes. Genes are passed from
generation to generation.
Some forms of genes (alleles) are dominant,
while others are recessive.
Genes from parents are segregated during
gamete formation.
Alleles for different genes USUALLY
segregate independently of one another
(exception is when the genes are linked)
3. What is beyond dominant and recessive
alleles?
Some alleles are neither dominant nor
recessive, and many traits are controlled by
multiple alleles or multiple genes.
a. What is incomplete dominance?
Cases in which one allele is not completely
dominant over another. (i.e. white flower X
red flower = pink flower)
b. What is codominance?
Situation in which both alleles contribute to
the phenotype. (i.e. black chicken X white
chicken = erminette “speckled” chicken with
black AND white feathers)
c. What is caused by multiple alleles?
Genes that have more than two forms,
therefore represented by more than two alleles
(i.e. blood type is determined by 3 alleles: A,
B and O)
d. What are polygenic traits?
Traits controlled by the interaction of two or
more genes (i.e. skin and eye color)
2
J.Adams/AEC/2010
PDP Cornell Notes
Questions
4. How can Mendel’s principles be applied?
Answers
Patterns of inheritance observed in Mendel’s
pea plants have also be observed in fruit flies
and other organism, including humans.
5. What is the relationship between genetics
and the environment?
Genes and environment work hand in hand to
determine the traits of an organism (nature vs.
nurture)
Vocabulary:
Focus Words: Independent assortment; two factor
cross; dominance; variation; environment
Independent Assortment: independent segregation
of genes during the formation of gametes
Summary (20 word max): Mendel observed
independent assortment by performing a two factor
cross. Dominance comes in different forms and
environment increases genetic variation.
Incomplete Dominance: situation in which one
allele is not completely dominant over another
Codominance: situation in which both alleles of a
gene contribute to the phenotype of the organism
[com-“with, together”]
Multiple Alleles: three or more alleles of the same
gene
Polygenic Traits: trait controlled by two or more
genes [poly—“many”; genos—“race, offspring”]
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J.Adams/AEC/2010