Transcript pedigrees poweropint 2015

Sex Determination
• Female sex chromosomes: XX
• Male sex chromosomes: Xy
In humans, the X and
Y chromosomes
control the sex of
offspring.
Outcome is always 50% chance
of a male, and 50% chance of a
female
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
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 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 autosomal or Xlinked and 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 _______