Mendel’s Experiments
• Each gamete
carries only one
allele for seed
shape, because
the alleles have
segregated
during meiosis.
Predicting Outcomes of Genetic Crosses
• Mendel realized the principles of probability
could be used to explain the results of genetic
crosses.
• Probability: the likelihood a particular event will
occur.
• The Basics of Probability:
– What is the probability of flipping a coin to
heads.
– The more trials, the closer to expected ratio.
– Past outcomes do not affect future outcomes.
Predicting Outcomes of Genetic Crosses
• Organisms can only pass on 1
of their 2 alleles for each trait
(like flipping a coin)
• Homozygous:
– Have 2 identical alleles
for a specific trait.
– AA or aa
• Heterozygous
– Having 2 different
alleles for a specific
trait.
– Can pass on either a
dominant or a
recessive trait
– Aa