Download 4.2 Probability and Heredity

4.2 Probability and Heredity
The principles of probability predict the results of a particular event.
Probability is a number that describes how likely it is that an event will occur.
The Laws of Probability predict what is likely to occur, not necessarily what
will occur.
Independence of events – each event occurs independently of others.
Probability and Genetics
Mendel was the first scientist to recognize that the principles of probability can be
used to predict the results of genetic crosses.
Punnett Squares
o Tools used to help understand how the laws of probability apply to
genetics
o Chart that shows all of the possible combinations of alleles that can
result from a genetic cross
o Determines probability of a particular outcome
o In a genetic cross, the allele that each parent will pass on to is offspring
is based on probability
Phenotype:
physical appearance or visible traits
Genotype:
genetic make-up or allele combination
Homozygous:
2 identical alleles
Heterozygous: 2 different alleles (hybrid)
Codominance: alleles are neither dominant nor recessive and both are
expressed.