1. Deducing Genotypes
Song Hee Bae
IB1 Biology

2. Pedigree Charts How a trait can pass Whether dominant or recessive
Whether sex-linked or not
Sex-linkage
Ex) color blindness, hemophilia
Similar to family tree
Squares = male
Circles = female
Shaded = affected
Not shaded = unaffected

3. Huntington’s Disease Whether mother’s genotype is Hh or HH
Consider genotypes of next generation
Affected people
First daughter
Forth son
Fifth son
Unaffected people
Second and third sons
Grand daughter
Mother must be Hh

4. Using Test Crosses
To distinguish between Dominant X Dominant / Dominant X Recessive
A subject is crossed with homozygous w w W Ww Ww W Ww Ww ww w w Ww W Ww Ww w ww ww
W – long ears w – short ears

5. Vocabulary
Pedigree chart: diagram which are constructed to show biological relationships.
Sex linkage: any genetic trait whose allele has its locus on the X chromosome.
Test cross: a method to distinguish whether the individuals that might have the same phenotype are influenced by dominant / recessive allele.
Reference
IB Study guides page 29
Pearson Biology SL page 105, 108~109