Download Biology 12AP Genetics

Biology 11E
Genetics
Name ________________________
Reference Chapter 14
3.A.3 The chromosomal basis of
inheritance provides an
understanding of the pattern of
passage (transmission) of genes
from parent to offspring
14.1, 14.2, 14.3, 14.4
4.C.2: Environmental factors
influence the
expression of the genotype in an
organism.
14.3
C.4: The diversity of species
within an ecosystem may
influence the stability of the
ecosystem.
14.3
23.2
54.2
56.1
Biology11E Genetics notes
• Sickle cell anemia
• Tay-Sachs disease
• Huntington’s disease
• X-linked color blindness
• Trisomy 21/Down syndrome
• Klinefelter’s syndrome
• Reproduction issues
• Civic issues such as ownership
of genetic information, privacy,
historical contexts, etc.
• Height and weight in humans
• Flower color based on soil pH
• Seasonal fur color in arctic
animals
• Sex determination in reptiles
• Density of plant hairs as a
function of herbivory
• Effect of adding lactose to a
Lac + bacterial culture
• Effect of increased UV on
melanin production in animals
• Presence of the opposite
mating type on pheromones
production in yeast and other
fungi
• Darker fur in cooler regions of
the body in certain mammal
species
• Alterations in timing of
flowering due to climate
changes
No illustrative examples listed in
the Curriculum Framework.
Page 1
Reference Chapter 14
1.
Who is the most famous scientist in the field of genetics?
__________________________________________________________
2.
What type of organism did he study to learn
about inheritance? ____________________
3.
What was the first major observation that
Mendel made when he crossed two strains of
pure-breeding peas and observed a particular
characteristic that showed two traits, such as
purple and white flowers?
_______________________________
_______________________________
_______________________________
______________________________________________________________________________
_____________________________________________
Biology11E Genetics notes
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Use the Word study tools on the textbook website for chapter 14.
Differentiate between:
A character is an observable heritable feature.
and a trait is any detectable variant in a genetic character.
True breeding refers to plants that produce offspring of the same variety when they self-pollinate.
and hybridization in genetics is, the mating, or crossing, of two true-breeding varieties.
P generation: The parent individuals from which offspring are derived in studies of inheritance; P
stands for “parental.”
and F1 generation: The first filial, or hybrid, offspring in a series of genetic crosses.
F2: Offspring resulting from interbreeding of the hybrid F1 generation.
Dominant: An allele that is fully expressed in the phenotype of a heterozygote.
and recessive alleles: An allele whose phenotypic effect is not observed in a heterozygote.
Biology11E Genetics notes
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4.
Did Mendel observe the same phenomenon when he looked at other pea characteristics
besides flower colour? He observed the same pattern of inheritance (complete dominance) in six
other characters, each represented by 2 distinctly different traits.
How did Mendel describe the trait that showed up in the F1 generation?
________________________________________________________________________
How did he describe the trait that disappeared in the F1 generation and reappeared in the
F2 generation? ___________________________________________________________
Biology11E Genetics notes
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See Campbell’s activity 14.1 Monohybrid cross
5.
This box summarizes Mendel’s pea-breeding experiments:
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Alternative versions of a gene are
called ______________________
Where the gene is found on a
particular chromosome is called
the ______________ for that
gene.
Biology11E Genetics notes
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6.
What are the four main ideas that make up Mendel’s model to explain inheritance of a
single character? (This is also called a single-factor cross. When the F1 generation are
crossed, it is referred to as a monohybrid cross.)
1. Alternative variations of genes account for variations in inherited characters. (purple
flower allele and white flower allele are 2 DNA variations possible at the flower colour
locus on one of a pea plants chromosomes.)
2. For each character an organism inherits 2 alleles, one from each parent.
3. If the 2 alleles at a locus differ then the dominant allele determines the organisms
appearance and the other allele, which is recessive has no noticeable effect on the
organisms appearance.
4. The law of segregation states that when gametes form by meiosis, the 2 alleles will
separate into different gametes.
This box illustrates
Mendel’s Law of
Segregation.
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_____________________
_____________________
_____________________
_____________________
____________
Biology11E Genetics notes
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7.
Be sure that you understand the following genetics vocabulary:
Homozygous: Having two identical alleles for a given gene.
Heterozygous: Having two different alleles for a given gene.
Phenotype: The physical and physiological traits of an organism, which are determined by its
genetic makeup.____________________________________________
Genotype: The genetic makeup, or set of alleles, of an organism._
This is an illustration of phenotype versus genotype
Biology11E Genetics notes
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Concept 14.2: The laws of probability govern Mendelian inheritance
Campbell’s Activity 14.2 – Gregor’s Garden
8.
The Test Cross
How can we use a test cross to determine the genotype of an organism showing the dominant
phenotype? (See Campbell’s activity 14A2, 3)
______________________________
We are predicting probabilities. These
vary depending on the number of
traits in the cross.
______________________________
______________________________
______________________________
Biology11E Genetics notes
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9.
Mendel’s observations of two characteristics at the same time, led to his Law of
Independent Assortment? (Campbell’s Activity 14.1: Dihybrid Cross)
He started by asking the question: Will two different characteristics be inherited together
as a unit, or independently of each other?
The diagram below shows the predicted results from the two possible hypotheses:
Which of the two hypotheses was supported by Mendel’s data?
Independent assortment!
_____________________________________________
Biology11E Genetics notes
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Do Concept Check 14.1 p 269
Go to appendix A -10
Biology11E Genetics notes
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10.
Alleles segregate into gametes following rules of probability
The expected proportions of offspring genotypes can be calculated following the rules of
probability:
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Biology11E Genetics notes
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How can we use the two rules of probability to solve more complex genetics problems?
For example:
Solve this problem: In the trihybrid cross, PpYyRr × Ppyyrr, what are the chances that an
individual will exhibit at least two recessive traits?
The first step is to list the genotypes that would result in at least two recessive traits:
The second step is to figure out the probability of each genotype, using the law of multiplication:
The third step is to add together all the different probabilities, using the law of addition:
Concept Check 14.2 p 271
Biology11E Genetics notes
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Degrees of Dominance
11.
What is Incomplete Dominance?
Activity 14.3: Incomplete Dominance
The situation in which the phenotype of
heterozygotes is intermediate between the
phenotypes of individuals homozygous for
either allele.
___________________________________
What ratio of phenotypes is expected in the
F2 generation?
1 red to 2 pink to 1 white.
___________________________________
Biology11E Genetics notes
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12.
What is Codominance?
The situation in which the phenotypes of both alleles are exhibited in the heterozygote because
both alleles affect the phenotype in separate, distinguishable ways.
Blood Types are a good example of Multiple Alleles AND Codominance:
Human blood has three
alleles of a single gene.
The A and B refer to
two carbohydrates that
may be found on the
surface of human
blood cells. Type O
has neither
carbohydrate.
__________________
__________________________
Biology11E Genetics notes
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In epistasis, a gene at one locus alters the phenotypic expression of a gene at a second locus:
In mice, black coat colour is dominant to brown. BB is a black phenotype and bb is a brown
phenotype. However a second gene determines whether or not the pigment will be deposited in
the hair. The dominant allele, C results in deposition. cc will result in an albino.
Biology11E Genetics notes
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In polygenic inheritance, more than one gene contributes to the inheritance of a character. There
is an additive effect of more than one gene on a single phenotype. For example, in the inheritance
of skin colour, at least 3 different genes are involved. Which individual inherits the darkest
skin? _________________The lightest? __________________
Biology11E Genetics notes
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13.
Pleiotrophy
the ability of genes to affect an organism in more than one way.
eg sickle-cell allele
Biology11E Genetics notes
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When both genetic and environmental factors affect phenotype the characters are referred
to as being multifactorial. Gene expression can depend on environmental factors. For
example, in the hydrangea, the colour of the flowers depends on the acidity and aluminum
content of the soil:
Concept Check 14.3 p 275
1. Epistasis: A type of gene interaction in which one gene alters the phenotypic effects of
another gene that is independently inherited.
Incomplete dominance: The situation in which the phenotype of heterozygotes is
intermediate between the phenotypes of individuals homozygous for either allele.
2.
3.
Biology11E Genetics notes
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Many human characters follow Mendelian patterns of inheritance. Widow’s peak and
attached earlobes are two examples.
Pedigree Analysis
Ww = widows peak
- studying the inheritance of human genetic traits within a family
ff = attached earlobe.
Note: the allele for widow’s peak is dominant over the allele for no widow’s peak; the allele for
free earlobe is dominant over the allele for attached earlobe.
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Pedigree analysis is useful to:
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_____________________
Biology11E Genetics notes
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Recessive alleles
Albinism
Describe two other recessively inherited disorders. p.278
Sickle cell anemia
Cystic fibrosis:
People who are heterozygous for a recessive autosomal mutation are called __carriers__.
What is a problem associated with the mating of close relatives?
The probability of passing on recessive traits increases greatly. ____
Biology11E Genetics notes
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Dominantly inherited disorders.
Give an example of a human genetic disorder that is caused by a dominant autosomal mutation:
Achondroplasia, a form of dwarfism. ________________________________________
Huntington’s disease
Biology11E Genetics notes
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15.
Fetal Diagnosis is used to determine whether the fetus carries a genetic disorder:
______________________________________________________________________________
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Biology11E Genetics notes
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Do Concept Check 14.4
Complete all genetics problems pp. 284 to 285 and
Scientific inquiry p.285
Biology11E Genetics notes
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