Download gene20PedigreesSickle-cell

LESSON TITLE: Pedigrees and Sickle-cell Anemia
TIME REQUIRED: 100 min
SUBJECT / STRAND: SBI 3U, Genetic Continuity
GRADE: 11U
EXPECTATIONS COVERED:
ASSESSMENT:
Overall Expectation:
Formative
- demonstrate an understanding of the necessity of meiosis and describe
the importance of genes in transmitting hereditary characteristics
according to Mendel’s model of inheritance
Specific Expectations:
- predict the outcome of various genetic crosses.
- describe genetic disorders (e.g., Down syndrome, cystic fibrosis,muscular
dystrophy, fragile X syndrome) in terms of the chromosomes affected,
physical effects, and
BACKGROUND KNOWLEDGE:
- genetics terms: chromosome, DNA
- processes: mitosis, meiosis
SAFETY CONCERNS?
None
LESSON DESCRIPTION:
- (40 min) Introduction to Pedigrees, Pedigree analysis
- (20 min) Case Study: A Mysterys
o Students work in groups to solve genetics and pedigree problem
- (40 min) Sickle-cell Anemia
o Pedigree work sheet (part of test review)
REFLECTION:
Case Study: A Mystery
There are four different ABO blood types as shown in Table 2. The
alleles for blood types A and B are codominant but are dominant over
the allele for type O. The rhesus factor is a blood factor that is
regulated by a gene. The Rh-positive allele is dominant over the Rhnegative allele. In this activity, you will solve a murder mystery using
genetics.
Phenotypes
type A
type B
type AB
type O
Genotypes
IAIA, IAIO
IBIB, IBIO
IAIB
IOIO
Evidence:
As a bolt of lightning flashed above Black Mourning Castle, a scream echoed from the den of Lord Hooke.
When the upstairs maid peered through the door, a freckled arm reached for her neck. Quickly, the
maid bolted from the doorway, locked herself in the library, and telephoned the police. Inspector
Holmes arrived to find a frightened maid and the dead body of Lord Hooke. Apparently, the lord had
been strangled. The inspector quickly gathered evidence. He noted blood on a letter opener, even though
Lord Hooke did not have any cuts or abrasions. The blood sample proved to be type O, Rh-negative. The
quick-thinking inspector phoned the family doctor for each family member’s medical history. The
pedigree shown includes the relatives who were in the castle at the time of Lord Hooke’s murder.
The inspector gathered the information in Table 3.Some
of the family members were deeply tanned, so the
inspector found it difficult to determine whether or not
freckles were present on their arms. Note: having
freckles is an inherited trait and the allele for freckles
is dominant over the allele for no freckles.
The crafty inspector drew the family close together
and, while puffing on his pipe, indicated that he had
found the murderer. He explained that one of the heirs
to the fortune was not Lord Hooke’s biological child. The
inspector believed that the child committed the murder.
Analysis:
(a) Who was the murderer?
State the reasons for your
answer.
(b) Describe the procedure
you followed to obtain your
answer.
(c) How did the inspector
eliminate the other family
members?
SBI 3U – Genetics
Name: ___________________________
Hemophilia Pedigree – Queen Victoria
SBI 3U – Genetics
___________________
Name:
1. How many generations are represented in the pedigree? _____________
2. In generation I, which parent is HETEROZYGOUS for the recessive allele? _______
3. Which individual (represented by the #) in generation II marries a spouse who
is HOMOZYGOUS DOMINANT? __________________
4. Which generation contains the most carriers?_________________
5. Can 2 carriers produce an individual with Sickle-Cell Anemia? Is there evidence
of this in the pedigree? Explain.
______________________________________________________________
______________________________________________________________
6. Can a normal HOMOZYGOUS individual produce offspring with Sickle-Cell Anemia?
Is there evidence of this in the pedigree? Explain.
______________________________________________________________
______________________________________________________________
7. Which parents produce 2 different sex children with Sickle-Cell Anemia? (Use
generation and individual – e.g. I-1) _____________________________________
1. Tay-Sachs disease is a fatal genetic disorder caused by a recessive
allele. The pedigree chart below shows the appears of the disease in
three generations of a family. Tell the genotype or possible genotypes
of each member of the family. Be sure to define your variables.
Key:
1
2
(from a family
with no history
of TaySachs)
= Normal male
= Tay-Sachs male
= Normal female
3
4
5
6
7
= Tay-Sachs female
8
9
10
2. Draw a pedigree chart for the family described below and use the chart
to determine the genotype or possible genotypes of each member of the
family. Be sure to define your variables.
In humans, having freckles is dominant over not having them. Both
Mr. And Mrs. Chambers have freckles. Of their three children, Robin
and Daniel have freckles but Alex does not. Robin marries Stephen,
who does not have freckles. They have two children, Kevin and Beth,
who do not have freckles. Daniel marries Diane who also has
freckles. They have one son, Phillip, who also has freckles. Alex
marries Mary, who has freckles. They have one daughter, Norma, who
does not have freckles.