Transcript pedigrees powerpoint 2015

Do Now Practice Problems:
1. The Jones family is planning to have another
child. Mrs. Jones is the proud mom of 3 healthy
boys. In her heart, she has always wanted a
daughter. What are her chances of her next baby
being a girl? Show with a Punnett square.
2. In cats, black fur is codominant to orange fur.
Heterozygotes are black & orange, called “calico”.
Fur color is also sex-linked. In a Punnett, cross a
black female with an orange male. Show the %
results of the offspring.
Practice Problem
 The Jones family is planning to have another child.
Mrs. Jones is the proud mom of 3 healthy boys. In
her heart, she has always wanted a daughter.
What are her chances of her next baby being a
girl? Show with a Punnett square.
X
y
X
X
XX
XX
50% chance girl
Xy
Xy
50% chance boy
2. In cats, black fur is codominant to orange fur.
Heterozygotes are black & orange, called “calico”.
Fur color is also sex-linked. In a Punnett, cross a
black female with an orange male. Show the %
results of the offspring.
Let
B= black
O= orange
BO= calico
Genotypes:
50% XBXO
50% Xby
Phenotypes:
50% Calico female
50% Black male
XB
XO
y
XB
XBXO
XBXO
XBy
XBy
Pedigree Charts
The family tree of genetics
What is a Pedigree?
• A pedigree is a chart of the genetic history
of family over several generations.
• Scientists or a genetic counselor would find
out about your family history and make this
chart to analyze.
Constructing a Pedigree
 Female
 Male
Connecting Pedigree Symbols
Examples of connected symbols:
 Parents
 Siblings
Example
 What does a pedigree chart look like?
Symbols in a Pedigree Chart
 Affected
 “Normal”
 Deceased
Interpreting a Pedigree Chart
Determine whether the disorder is dominant or
recessive.
– If the disorder is dominant, one of the
parents must have the disorder.
– If the disorder is recessive, neither
parent has to have the disorder because
they can be heterozygous.
Example of Pedigree Charts
 Dominant or Recessive?
Answer
 Dominant
Example of Pedigree Charts
 Dominant or Recessive?
Answer
 Recessive
Summary
 Pedigrees are family trees that explain your
genetic history.
 Pedigrees are used to find out the
probability of a child having a disorder in a
particular family.
 To begin to interpret a pedigree, determine if
the disease or condition is dominant or
recessive.
I
1
2
II
1
2
3
1
III
IV
Let
H= hitchhiker’s thumb
h= straight thumb
1
2
2
4
3
4
3
1. What is the genotype of IV-1?
2. What is the genotype IV-3?
3. What is the genotype of III-1?
4. What is the genotype III-2?
5. What is the genotype II-3?
6. Is it possible for individual IV-2 to be a carrier? Why?
Let
D= normal
d=- sickle cell
7. Which members of the family above are afflicted
with sickle cell anemia?
8. How are individuals III-4 and III-5 related?
9. How are individuals I-1 and I-2 related?
10. How are individuals II-7 and III-2 related?
11. How are individuals I-2 and III-5 related?
12. How many children did individuals I-1 and I-2 have?
13. How many girls did II-1 and II-2 have?
How many have sickle cell anemia?
14. Label the genotype for:
II-1 _______ II-2 _______ II-6 ________ II-7 ________
II-8 _______ III-1_______ III-3 _______