Download Biol 211 (2) Chapter 14 KEY

Professor: Hufford/Biederman
S.I. Leader: Stephanie Schneider
Biology 211 (2) Week 10!
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Chapter 14!
VOCABULARY: !
Allele: Different version
of genes; Controls
whether the seed shape is
round or wrinkled
Blending inheritance:
The observation that
genes from two parents
blend together in the
offspring, as if the genes
mix like paint
Dominant: Referring to an allele
that determines the same
phenotype when it is present in
homozygous or heterozygous
form
Gene: Controls the actual
seed shape
Genotype: All the alleles
of every gene present in
a given individual
Heterozygous: Having two
different alleles of a gene
Homozygous: Having two
identical alleles of a gene
Hybrid: The offspring of
parents from two
different strains,
populations, or species
Linkage: In genetics, a physical
association between two genes
because they are on the same
chromosome
Particulate inheritance:
The observation that
genes from two parents
do not blend together in
offspring, but instead
remain separate or
particle-like
Phenotype: The
Principle of independent
detectable/physical traits assortment: Able to pass on traits
of an individual
you have acquired throughout
your lifetime
Principle of segregation:
During the formation of
eggs and sperm, the two
members of each gene
pair must segregate and
separate into different
gamete cells. Each
gamete has one member
(or allele) of a gene pair
Pure line: Parental
generaton
Reciprocal cross: A cross
Traits: Any observable
in which the mother’s and characteristic of an
father’s phenotypes are
individual
the reverse of that
examined in a previous
cross
F1 generation: the first
filial/ the first offspring
from the pure line
(parental generation)
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Recessive: Referring to an allele
whose phenotypic effect is
observed only in homozygous
individuals
Heredity: The transmission of
traits from parents to offspring
via genetic information
Professor: Hufford/Biederman
S.I. Leader: Stephanie Schneider
KEY CONCEPTS: !
1. Compare and contrast the concepts of particulate inheritance, inheritance of acquired
characteristics, and blending inheritance. Are traits inherited like paint or marbles?
Explain.
a. Blending Inheritance: Traits are going to combine like paint
b. Particulate Inheritance: Traits are inherited like marbles (particles)
c. Inheritance of acquired characteristics: Able to pass on traits you have acquired
throughout your lifetime (Changing your body by going to the gym, getting in
an accident and becoming disabled, dying your hair)
2. What is the first Model System in Genetics? What are other examples of Model
Systems?
a. Garden Peas used by Gregor Mendel
b. Mice, rabbits, corn, flies, arabidopsis
3. Compare and contrast genotype and phenotype. Is “Aa” heterozygous or homozygous
and is it a genotype or phenotype? Is “A” a dominant or a recessive allele?
a. A genotype describes the alleles present, while phenotype describes the
physical appearance the genotype makes. “Aa” is a heterozygous genotype,
while the phenotype would be shown as the dominant trait. “A” is a dominant
allele.
4. Do individuals with the same genotype always have the same phenotype? Why or why
not?
a. No, because the environment plays a role in the phenotype. A clone of an
animal has the same genotype as the original animal, but one of the animals
may have been malnourished, so they will not look the same.
5. Are pure-line peas homozygous or heterozygous? Do the terms homozygous and
heterozygous describe an organism’s genotype or phenotype?
a. Pure-lines are homozygous and always produce offspring with the same
phenotype. Hybrids are heterozygous.a
b. Homozygous and heterozygous describe an organisms alleles, therefore it
describes their genotype. However, the phenotype is affected by whether the
genotype is homozygous or heterozygous.
6. Describe the difference between independent and dependent assortment. When does
dependent assortment occur?
a. Independent assortment is when the alleles of different genes are inherited
independently of each other.
Professor: Hufford/Biederman
S.I. Leader: Stephanie Schneider
b. Dependent assortment is when the transmission of one allele depends on the
transmission of another. This occurs when the alleles on a chromosome are
close in proximity and linked.
7. Why did Mendel design reciprocal crosses (what did these reciprocal crosses
demonstrate)?
a. He wanted to determine if gender influence inheritance. He performed a
reciprocal cross, which is a cross in which the mother’s and father’s phenotypes
are the reverse of that examined in a previous cross. The result of the two
crosses were identical.
8. What is the ratio of phenotypes in the F2 generation if you begin with pure line
yellow-seeded plants (YY) and pure-line green-seeded plants (yy). What is the
genotype ratio in the F1 and F2 generations? Draw Punnett Squares to help answer the
problem.
a. Parent 1: (YY)
Parent 2: (yy)
b. F1
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c. F2
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d. Ratio of phenotypes in F2—> 3:1, so . . . 75% will be yellow-seeded and 25% will
be green seeded
e. Genotype ratio in F1—> 4/4 Yy, so . . . 100% Yy (Heterozygous)
f. Genotype ratio in F2—> 1/4 YY, 1/2 Yy, 1/4 yy, so . . . 1:2:1
9. Simple practice with Punnett Squares:
a. http://glencoe.mheducation.com/sites/0078778066/student_view0/chapter5/
math_practice.html
b. http://www.mhhe.com/biosci/genbio/virtual_labs/BL_05/BL_05.html
Professor: Hufford/Biederman
S.I. Leader: Stephanie Schneider
10. Practice with Dihybrid Punnett Squares:
a. http://www.biologycorner.com/bio2/genetics/notes_dihybrid.html
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