co Aaron Darcie Diana Geeta Kristin RouJia Introduction Our teachable unit Heredity module Embedded within Introductory Biology course Prerequisites None high school level biology ID: 744822
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Slide1
HEREDITYYYYYYY
2015 July 17
c/o: Aaron, Darcie, Diana,
Geeta
, Kristin, Rou-JiaSlide2
Introduction
Our “teachable unit”: Heredity module
Embedded within Introductory Biology course
Prerequisites: None (high school level biology)Student population: First-year students, both majors or non-majors
Rou-JiaSlide3
Introduction
Our “teachable unit”: Heredity module
Embedded within Introductory Biology course
Prerequisites: None (high school level biology)Student population: First-year students, both majors or non-majors
Our “teachable tidbit”: Sex-linked traits
Rou-JiaSlide4
Introduction
Our “teachable unit”: Heredity module
Goals
Our “teachable tidbit”: Sex-linked traitsObjectives
Rou-JiaSlide5
Introduction
Our “teachable unit”: Heredity module
Goals
1) Understand how genes and chromosomes relate to traits2) Appreciate how traits are passed on from parents to offspring3) Comprehend the inheritance of genetic disorders
Our “teachable tidbit”: Sex-linked traits
Objectives
Rou-JiaSlide6
Introduction
Our “teachable unit”: Heredity module
Goals
1) Understand how genes and chromosomes relate to traits2) Appreciate how traits are passed on from parents to offspring3) Comprehend the inheritance of genetic disorders
Our “teachable tidbit”: Sex-linked traits
Objectives
1)
Be able to diagram a
single-trait
sex-linked cross and
predict
genotypic/phenotypic
percentages.
2
) Determine if a genetic disorder is sex-linked by analyzing a pedigree. 3) Distinguish between dominant versus recessive genetic disorders.
Rou-JiaSlide7
Prior knowledge
From the previous class:
Concepts/definitions students should be familiar with:
heterozygous vs homozygousrecessive
vs
dominant
genotype
vs
phenotype
carrier
a
utosomal single-trait crosses
Punnett
squares
AaronSlide8
Sex-linked traits
What is a sex-linked trait?!?
AaronSlide9
Sex-linked traits
What is a sex-linked trait?!?
Definition: A trait whose gene is located on a sex chromosome (almost always the X-chromosome).
AaronSlide10
Sex-linked traits
What is a sex-linked trait?!?
Definition: A trait whose gene is located on a sex chromosome (almost always the X-chromosome).
Why is this important/why should we care?AaronSlide11
Sex-linked traits
What is a sex-linked trait?!?
Definition: A trait whose gene is located on a sex chromosome (almost always the X-chromosome).
Why is this important/why should we care?Common sex-linked diseases:Colorblindness
Hemophilia
Duchenne
muscular dystrophy
Implications for genetic counseling
AaronSlide12
Clicker Question!
Which of the following genotypes is representative of an affected female for hemophilia, an X-linked recessive disorder?
AA
XaYaa
X
a
X
a
X
A
X
a
AaronSlide13
Clicker Question!
Which of the following genotypes is representative of an affected female for hemophilia, an X-linked recessive disorder?
AA
XaYaa
X
a
X
a
X
A
X
a
AaronSlide14
Clicker Question round 2
Which of the following genotypes is representative of a
carrier
for hemophilia, an X-linked recessive disorder?AAXaY
aa
X
a
X
a
X
A
X
a
AaronSlide15
Clicker Question round 2
Which of the following genotypes is representative of a
carrier
for hemophilia, an X-linked recessive disorder?AAXaY
aa
X
a
X
a
X
A
X
a
AaronSlide16
Clicker Question round 2
Which of the following genotypes is representative of a
carrier
for hemophilia, an X-linked recessive disorder?AAXaY
aa
X
a
X
a
X
A
X
a
Do you think males can be carriers for sex-linked disorders? Why?
AaronSlide17
Pedigrees!
What is a pedigree?
A visual representation of family history for a trait.
Standard notation for analyzing/constructing a pedigree:DianaSlide18
Pedigrees!
What is a pedigree?
A visual representation of family history for a trait.
Standard notation for analyzing/constructing a pedigree:
DianaSlide19
Female
Male
Pedigrees!
What is a pedigree?
A visual representation of family history for a trait.
Standard notation for analyzing/constructing a pedigree:
DianaSlide20
Female
Male
Descent Line
Mating Line
Pedigrees!
What is a pedigree?
A visual representation of family history for a trait.
Standard notation for analyzing/constructing a pedigree:
DianaSlide21
Female
Male
Descent Line
Mating Line
I.1
I.2
Pedigrees!
What is a pedigree?
A visual representation of family history for a trait.
Standard notation for analyzing/constructing a pedigree:
Generation designation:
I, II, III, IV…
Individual designation:
1, 2, 3, 4…
Diana
II.1
II.2Slide22
Female
Male
Descent Line
Mating Line
I.1
I.2
Pedigrees!
What is a pedigree?
A visual representation of family history for a trait.
Standard notation for analyzing/constructing a pedigree:
Generation designation:
I, II, III, IV…
Individual designation:
1, 2, 3, 4…
Diana
II.1
II.2
Phenotype designation
Trait
Present
Trait
AbsentSlide23
Pedigree activity
Assume the pedigree below displays information about a recessive, X-linked disorder. Work with a partner to fill in the phenotypes for generation I individuals and genotypes and phenotypes for generation II individuals.
Working together in pairs, fill out the provided worksheet
X
A
Y
X
a
X
a
X
A
X
A
X
a
Y
KristinSlide24
Female
Male
Descent Line
Mating Line
I.1
I.2
Pedigrees!
What is a pedigree?
A visual representation of family history for a trait.
Standard notation for analyzing/constructing a pedigree:
Generation designation:
I, II, III, IV…
Individual designation:
1, 2, 3, 4…
Kristin
II.1
II.2
Phenotype designation
Trait
Present
Trait
AbsentSlide25
Pedigree activity
Assume the pedigree below displays information about a recessive, X-linked disorder. Work with a partner to fill in the phenotypes for generation I individuals and genotypes and phenotypes for generation II individuals.
Working together in pairs, fill out the provided worksheet
X
A
Y
X
a
X
a
X
A
X
A
X
a
Y
KristinSlide26
Pedigree activity
Assume the pedigree below displays information about a recessive, X-linked disorder. Work with a partner to fill in the phenotypes for generation I individuals and genotypes and phenotypes for generation II individuals.
Working together in pairs, fill out the provided worksheet
X
a
Y
X
A
X
a
X
A
X
a
X
A
Y
X
a
X
a
X
A
X
A
X
a
Y
KristinSlide27
Kristin
If II.2 and II.3 have children:
1) Is it possible for them to show the trait?
2) If so, can both boys and/or girls show the trait?
X
a
Y
X
A
X
a
X
A
X
a
X
A
Y
X
a
X
a
X
A
X
A
X
a
Y
What about Generation III?Slide28
Mating activity for Generation III!
Instructions
You have each received a pair of cards representing alleles for the proud parents-to-be from Generation II. Now:
Find a partner with the opposite color cards.Hold your cards behind your back, one in each hand.Have your partner randomly select one of your hands.
Place your selected card on the table.
Repeat 3-4 with your partner’s cards.
Now define your offspring’s genotype.
7)
ONE OF YOU
report your offspring by clicking the
appropriate choice.
GeetaSlide29
Geeta
C
lick in the resulting genotype of your offspring!
X
a
Y
X
A
X
a
X
A
X
a
X
A
Y
X
a
X
a
X
A
X
A
X
a
Y
X
a
X
a
X
A
X
a
X
a
Y
X
A
Y
Mating activity for Generation III!Slide30
Main
takeways
from today
You should be able to define what a sex-linked trait is and understand their heredity.You should be able to analyze a pedigree and predict the phenotypes and genotypes of the offspring.
DarcieSlide31
Summative Assessments
DarcieSlide32
Colorblindness
is an X-linked recessive trait. If a father who is X
R
Y has children with an XrXr mother, what is the probability (percentage) that a daughter born to the couple would be colorblind?a. 0%b. 25%c. 50%d. 75%e. 100%
DarcieSlide33
1) Analyze
the following pedigree for the pattern of inheritance, and answer the following questions. Assume that individuals II-1 and II-4 do not have the detrimental allele.
Is this a dominant or recessive trait? Additionally, circle the couple that best supports your reasoning and explain.
Is this a sex-linked trait? Why or why not?
What is the genotype of individual I-1? Explain your reasoning.
Darcie