Download Pedigrees - WordPress.com

PEDIGREES
Following Traits in Families
Pedigree: A diagram that follows the
traits through a family
Circles and Squares represent people
Shaded circles/squares represent people that
have the trait “being followed”
A half-shaded symbol represents a ‘carrier’
Pedigree analysis
• Pedigree analysis reveals Mendelian patterns in
human inheritance
• data mapped on a family tree
= male
= female
= male w/ trait
= female w/ trait
Simple pedigree analysis
11
33
44
What’s the
likely inheritance
pattern?
22
55
66
Genetic counseling
• Pedigree can help us understand the past & predict the
future
• Thousands of genetic disorders are inherited as simple
recessive traits
• from benign conditions to deadly diseases
• albinism
• cystic fibrosis
• Tay sachs
• sickle cell anemia
• PKU
•Douglas and Lauren have three children, two
girls and a boy.
This line indicates a family
Douglas
Children are
left to right,
oldest to
youngest
Lauren
•Douglas has brown hair. We will ‘follow’ this
trait. Show the brown hair trait by shading in
the circle
Douglas
Lauren
•Lauren has blonde hair so we do not shade
her in.
Douglas
Lauren
•Their oldest daughter and youngest son
have brown hair also.
Douglas
Lauren
•Shade them in as well.
Douglas
Lauren
You try:
• Ryan and Jessica have two children. Richard
and Sarah.
• Ryan does not have dimples, but Jessica
does.
• Richard has dimples but Sarah does not.
• Jessica’s parents both have dimples
• Jessica has a sister who does not have
dimples
• Follow the dimples trait
1) Blue Eyes
• Brandon is trying to figure out why he has blue eyes
when his mother father and brother all have brown
eyes.
• Draw a pedigree for Brandon and his mother, father
and brother.
• Looking at family pictures he finds out that is father’s
father had blue eyes.
• Later he also finds out that his mother’s mother has
blue eyes.
• Follow the blue eyes trait
2) Juan and Jamie have one daughter,
Anna. All of them have hitchhiker’s thumb.
• Anna marries a man named Adam
with a straight thumb.
• They have two sons the oldest has
hitchhikers thumb the youngest does
not.
• Follow the hitchhiker’s thumb trait
3) April and Anthony are brother and sister
they both have brown hair, their parents
both have brown hair
• Their mother’s father has blonde hair
• Their father’s mother has brown hair.
• Their mother’s sister has blonde hair.
• Their aunt got married and had two
blonde haired children with a blonde
haired man, one boy and one girl.
• Follow the blonde hair trait
4) Bob and Jane have 8 kids. Three
daughters, then three sons, then 2 more
daughters.
• Bob is blood type A. Jane is blood type
O. Child #1, 3, 7, 8 all have blood type A.
• The oldest daughter gets married to a
man with blood type O
• They have 3 girls, all with blood type A.
• Write the blood type genotypes for each
of the individuals
Is the trait followed below:
-Dominant?
-Recessive?
-Sex-Linked?
Explain how you know!