Biology Notes: Pedigree Charts
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2Name: _________________________________________________ Date: _______________ Period: ________
Biology Notes: Pedigree Charts
Directions: Fill in the blanks as we cover the topic in the PowerPoint.
Genetic Pedigrees
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Genetic pedigrees are like ____________________
____________________
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They show ____________________, but also can _______________ traits throughout a _______________
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Squares = ____________________
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Circles = ____________________
- Sometimes you will be given a scenario where the gender of a person/people is unknown, in this case
you can randomly decide the gender or you can use a triangle to represent this unknown.
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Shaded = __________ the trait (usually a disease)
- Sometimes you might see a half shaded shape or a shape with a dot in the center of it. This means that
that person is heterozygous/carrier. You can use this if you would like – I think it is helpful.
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Let’s create a simple pedigree…using PKU (Phenylketonuria) as an example
In case you were wondering…
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PKU is a ___________________ disease where sufferers ______________
PKU is caused by a mutation in a gene
on chromosome 12. The gene codes
a protein needed to properly _______________ certain foods.
for a protein called PAH (phenylalanine
It can lead to brain damage or be fatal if untreated.
hydroxylase), an enzyme in the liver.
This enzyme breaks down the amino
acid phenylalanine into other products
Creating a Pedigree
the body needs. When this gene is
mutated, the shape of the PAH
1) Manny and Rosa are married and both are healthy.
enzyme changes and it is unable to
2) They have 3 children.
properly break down phenylalanine.
3) Their oldest child, Jacob, has a recessive disorder called PKU.
Phenylalanine builds up in the blood
and poisons nerve cells in the brain.
4) Their middle child Erica and their youngest Matthew are healthy.
5) If healthy is dominant to PKU, fill in the missing genotypes:
Hint: make a key, start with what you know, & label the shapes with the names of the people in the
scenario. If you get stuck create a Punnett square to help you figure out all the possible genotypes.
If you don’t know the second allele use a “?” as a place holder.
Key
H = ____________
h = ____________
The Next Generation
5) Erica meets healthy Moe at college and the two become married.
6) Erica and Moe have 2 daughters.
7) Their youngest daughter Jamie shows signs of PKU while Amy does not.
8) Fill in the genotypes of the next four individuals adding to the pedigree above, start with what you know…
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