Wake-up
1.
Dihybrid Crosses
Dihybrid Cross
Punnett square that
examines the
inheritance of two
traits.
Law of Segregation
Allele pairs
separate
during gamete
formation
Law of Independent Assortment
Allele pairs will separate independently of each
other during meiosis
It is RANDOM!!!!
Mendel’s Experiment
Mendel decided to cross a purebred plant
possessing yellow and smooth seeds with a
green, wrinkled plant. What were his results?
YYRR x yyrr
Need to find all the possible combinations of allele
for each gene from each parent.
YR
Set up Punnett Square
yr
Mendel’s Experiment
He then decided to let the offspring of the F1
generation self-pollinate. What were his
results?
YyRr x YyRr
Need to find all the possible combinations of allele
for each gene from each parent.
YR, Yr, yR, yr
YR, Yr, yR, yr
Set up Punnett Square
Example #1
A man with hairy ears and is heterozygous for a
unibrow marries a woman that is a carrier for both
traits. What is the chance that their children will be
normal?
Non-hairy ears=H, Hairy ears=h, Unibrow=B, 2 eyebrows=b
Example #2
If a blue-eyed female is married to a heterozygous
brown-eyed male and the female is left-handed as is
the male, with brown eyes being dominant over blue
eyes and right-handedness dominate over lefthandedness, what will the offspring of this couple
look like?