Autosomal Recessive Disorders

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Transcript Autosomal Recessive Disorders

A man with a Widow’s Peak and a woman with a Widow’s peak have
only children who have Widow’s peaks. In another case, two people
with Widow’s peaks have some offspring who have no Widow’s Peak.
Is this possible? Why or why not?
a. What are the genotypes of the first set of parents?
a. What are the genotypes of the second set of parents?
A man with a Widow’s Peak and a woman with a Widow’s peak have
only children who have Widow’s peaks. In another case, two people
with Widow’s peaks have some offspring who have no Widow’s Peak.
Is this possible? Why or why not?
a. What are the genotypes of the first set of parents?
WW/WW or WW/Ww
a. What are the genotypes of the second set of parents?
Ww/Ww
Incomplete Dominance
A red rose (RR) is bred with a white rose (KK). Neither red nor white is
dominant nor recessive. What color will their offspring be?
Incomplete Dominance
A red rose (RR) is bred with a white rose (KK). Neither red nor white is
dominant nor recessive. What color will their offspring be?
100% pink roses
Autosomal Recessive Disorders
Albinism is an autosomal recessive disorder. If you cross 2
heterozygous individuals, what percent of their offspring will be albino?
Autosomal Recessive Disorders
Albinism is an autosomal recessive disorder. If you cross 2
heterozygous individuals, what percent of their offspring will be albino?
25% albino offspring
Autosomal Recessive Disorders
Cystic Fibrosis is a lethal autosomal recessive disorder. What is the
probability a child will have Cystic Fibrosis if one parent is
heterozygous for the disorder (a carrier) and the other parent is
homozygous dominant?
If two parents are both heterozygous for CF, what is the ratio of
offspring without CF to offspring with CF?
Autosomal Recessive Disorders
Cystic Fibrosis is a lethal autosomal recessive disorder. What is the
probability a child will have Cystic Fibrosis if one parent is
heterozygous for the disorder (a carrier) and the other parent is
homozygous dominant?
0% chance CF offspring
If two parents are both heterozygous for CF, what is the ratio of
offspring without CF to offspring with CF?
3:1
Autosomal Dominant Disorder
Huntington’s Disease is an autosomal dominant disorder. What is the
probability a child will have Huntington’s disease if his father is
heterozygous for the disorder, but his mother is homozygous recessive?
What does that tell us about Dad?
Autosomal Dominant Disorder
Huntington’s Disease is an autosomal dominant disorder. What is the
probability a child will have Huntington’s disease if his father is
heterozygous for the disorder, but his mother is homozygous recessive?
50% chance of offspring with HD
What does that tell us about Dad?
He has HD
X-linked Traits
Colorblindness is an X-linked recessive trait in humans. What is the
probability that a girl will be colorblind if her father is not Colorblind
(XNY)and her mother is a carrier(XNXn)?
X-linked Traits
Colorblindness is an X-linked recessive trait in humans. What is the
probability that a girl will be colorblind if her father is not Colorblind
(XNY)and her mother is a carrier(XNXn)?
0% chance of CB female offspring
X-linked Traits
What is the probability that a boy would be color blind if his father and
mother were both colorblind?
What is the probability that a girl would be color blind if her father is
color blind, but her mother is not (two choices)?
X-linked Traits
What is the probability that a boy would be color blind if his father and
mother were both colorblind?
100% CB male offspring
What is the probability that a girl would be color blind if her father is
color blind, but her mother is not (two choices)?
If mother is heteroz:50% chance of CB female offspring
If mother is homo dom: 0% chance of CB female offspring
Find the genotypes for all individuals below. You may need to complete Punnett Square(s) to prove your answer.
Based on the genotypes, does this pedigree show an autosomal dominant trait, autosomal recessive trait, or a sexlinked trait or not enough information?
DOMINANT
RECESSIVE
SEX-LINKED
Find the genotypes for all individuals below. You may need to complete Punnett Square(s) to prove your answer.
Based on the genotypes, does this pedigree show an autosomal dominant trait, autosomal recessive trait, or a sexlinked trait or not enough information?
DOMINANT
RECESSIVE
SEX-LINKED
Find the genotypes for all individuals below. You may need to complete Punnett Square(s) to prove your answer.
Based on the genotypes, does this pedigree show an autosomal dominant trait, autosomal recessive trait, or a sexlinked trait or not enough information?
DOMINANT
RECESSIVE
SEX-LINKED
Find the genotypes for all individuals below. You may need to complete Punnett Square(s) to prove your answer.
Based on the genotypes, does this pedigree show an autosomal dominant trait, autosomal recessive trait, or a sexlinked trait or not enough information?
DOMINANT
RECESSIVE
SEX-LINKED
Find the genotypes for all individuals below. You may need to complete Punnett Square(s) to prove your answer.
Based on the genotypes, does this pedigree show an autosomal dominant trait, autosomal recessive trait, or a sexlinked trait or not enough information?
DOMINANT
RECESSIVE
SEX-LINKED
Find the genotypes for all individuals below. You may need to complete Punnett Square(s) to prove your answer.
Based on the genotypes, does this pedigree show an autosomal dominant trait, autosomal recessive trait, or a sexlinked trait or not enough information?
DOMINANT
RECESSIVE
Not enough information…
SEX-LINKED
Find the genotypes for all individuals below. You may need to complete Punnett Square(s) to prove your answer.
Based on the genotypes, does this pedigree show an autosomal dominant trait, autosomal recessive trait, or a sexlinked trait or not enough information?
DOMINANT
RECESSIVE
SEX-LINKED
Find the genotypes for all individuals below. You may need to complete Punnett Square(s) to prove your answer.
Based on the genotypes, does this pedigree show an autosomal dominant trait, autosomal recessive trait, or a sexlinked trait or not enough information?
DOMINANT
RECESSIVE
Not enough information…
SEX-LINKED
WHITE BOARD PRACTICE PROBLEMS
In guinea pigs, the allele for black fur is dominant to the allele for white
fur. If two guinea pigs that are both heterozygous are mated, what is the
probability that an offspring will be white?
WHITE BOARD PRACTICE PROBLEMS
In guinea pigs, the allele for black fur is dominant to the allele for white
fur. If two guinea pigs that are both heterozygous are mated, what is the
probability that an offspring will be white?
25% White guinea pigs
In peas, green leaves (G) are dominant to white leaves (g). A genetic
cross is made between a heterozygous dominant (Gg) male plant and a
homozygous recessive (gg) female plant and 200 seeds are produced.
How many of the seeds would you expect to result in plants with green
leaves?
In peas, green leaves (G) are dominant to white leaves (g). A genetic
cross is made between a heterozygous dominant (Gg) male plant and a
homozygous recessive (gg) female plant and 200 seeds are produced.
How many of the seeds would you expect to result in plants with green
leaves?
100 green leaves
Colorblindness is a genetic disorder that affects 100% of children born
to colorblind parents, and generally affects many more males than
females. The inheritance pattern for colorblindness is BEST described
as __________.
•
•
•
•
Dominant
Recessive
Sex-linked
Not enough info
Colorblindness is a genetic disorder that affects 100% of children born
to colorblind parents, and generally affects many more males than
females. The inheritance pattern for colorblindness is BEST described
as __________.
•
•
•
•
Dominant
Recessive
Sex-linked
Not enough info
A group of 4,000 people are surveyed for natural hair type, which usually shows an
incomplete dominant inheritance pattern. They are asked if their hair is naturally
straight, curly, or wavy. The results of the survey are shown in the table
below. Based on the data in the table, approximately what proportion (fraction) of
people in the study have curly hair?
A group of 4,000 people are surveyed for natural hair type, which usually shows an
incomplete dominant inheritance pattern. They are asked if their hair is naturally
straight, curly, or wavy. The results of the survey are shown in the table
below. Based on the data in the table, approximately what proportion (fraction) of
people in the study have curly hair?
991/4000
Approx: 1/4
Cystic Fibrosis is a genetic disease that affects mucus cells in the lungs. The
disease affects only those individuals that have a homozygous recessive genotype
(ff). A Punnett Square for a cross between two individuals that are heterozygous
carriers for the disease is shown below. If the couple decides to have children,
what is the predicted phenotypic ratio of normal children to children with Cystic
Fibrosis?
Cystic Fibrosis is a genetic disease that affects mucus cells in the lungs. The
disease affects only those individuals that have a homozygous recessive genotype
(ff). A Punnett Square for a cross between two individuals that are heterozygous
carriers for the disease is shown below. If the couple decides to have children,
what is the predicted phenotypic ratio of normal children to children with Cystic
Fibrosis?
3:1
Huntington's disease is a genetic disease caused by an autosomal dominant allele,
meaning that anyone with a homozygous dominant (HH) or heterozygous (Hh)
genotype has the disease. Researchers studying people with a family history of
Huntington's conduct genetic tests to determine genotypes and record the results in
the table below. Based on the data in the table, approximately what proportion of
people in the study have Huntington's disease?
Huntington's disease is a genetic disease caused by an autosomal dominant allele,
meaning that anyone with a homozygous dominant (HH) or heterozygous (Hh)
genotype has the disease. Researchers studying people with a family history of
Huntington's conduct genetic tests to determine genotypes and record the results in
the table below. Based on the data in the table, approximately what proportion of
people in the study have Huntington's disease?
320/412
Approx: 3/4
The Punnett Square above shows the possible allele combinations in the offspring of
a human male with male–pattern baldness. Male–pattern baldness is an X–linked
trait, and is represented by an Xb in the Punnett Square below. However, the allele
combinations in the offspring in the Punnett square are not reasonable because
The Punnett Square above shows the possible allele combinations in the offspring of
a human male with male–pattern baldness. Male–pattern baldness is an X–linked
trait, and is represented by an Xb in the Punnett Square below. However, the allele
combinations in the offspring in the Punnett square are not reasonable because
Crossing two men!
Huntington's Disease is an autosomal dominant trait in humans. Which of the
following pedigrees does NOT represent a possible inheritance pattern for
Huntington's Disease?
Huntington's Disease is an autosomal dominant trait in humans. Which of the
following pedigrees does NOT represent a possible inheritance pattern for
Huntington's Disease?
Can’t get dominant traits in offspring of homozygous
recessive parents
If the pedigree below shows a genetic disease with a simple recessive inheritance
pattern (qq), what are the genotypes of individuals III–3 and III–4?
If the pedigree below shows a genetic disease with a simple recessive inheritance
pattern (qq), what are the genotypes of individuals III–3 and III–4?
Qq and Qq
Why?
They have two
homozygous
recessive offspring
If the pedigree below shows the inheritance pattern of an X–linked trait, what is the
chance that individual II–5 is a carrier?
If the pedigree below shows the inheritance pattern of an X–linked trait, what is the
chance that individual II–5 is a carrier?
100% chance that II-5
is a carrier
Why?
She has a homozygous
recessive offspring