1. Pedigrees

2. Pedigrees Show how traits are passed on in a family Female Male = =
See purple booklet after page 16 OR blue page 57 for pedigree symbols (these are on your diploma exam data sheet).
Line down from a horizontal line indicates offspring.
Oldest offspring always on the left
Affected individuals are shaded in
Heterozygous individuals half shaded in (sometimes)

3. Modes of Inheritance see purple pages 15, 16
Autosomal
Recessive
Autosomal
Dominant
Sex Linked
Males mostly affected
Males inherit sex-linked trait from mothers
Girls must have
affected fathers
Aa or AA = affected
Affected need only
have 1 affected parent
Affected (Aa) parents can have unaffected children (aa)
aa = affected
May skip 1 or more
Generations (recessive trait hidden for generations)
2 unaffected may have affected
2 affected will have all children affected
for more details see -
Blue booklet: pages 54, 55

4. Albinism Recessive? Dominant? Sex-linked? not dominant
Must be autosomal recessive. For this condition, affected individuals are homozygous recessive – lack enzyme to produce melanin.
HINT: what do these
symbols mean?
Recessive?
Dominant?
Sex-linked?

5. Pedigree Analysis
What is
this
pedigree
showing?

6. Why is inbreeding not recommended?
Chance of
recessive
condition
showing up
in offspring
is increased!

7. Lets’ draw a pedigree for Jason’s family
Sister (28) – unaffected
Jason (27) - unaffected
Brother (25) – affected
Identical twin brothers (18) – unaffected
Mother (46) – unaffected
Father (45) – affected
Paternal sister (43) – affected
Paternal grandmother (77) – unaffected
Paternal grandfather (79) - affected
Jason

8. Pedigree Questions All pedigree questions:
Today
Go to…purple - after page 16 – page 2 (Tay-Sachs disease)…
orange page 48 – 50
Together: start page 51…
All pedigree questions:
Purple: page 2 – 5 (after page 16)
Orange: pages
Blue: page 33 – 36

9. All pedigree questions: Purple: page 2 – 5 (after page 16)
All X-linked Questions:
Orange: pages 36 – 41
Blue: page 48
All pedigree questions:
Purple: page 2 – 5 (after page 16)
Orange: pages
Blue: page 33 – 36
Pedigree sheet