Transcript Probability and Punnett Squares

Probability and Punnett Squares
Probability is a way of expressing
knowledge or belief that an event
will occur or has occurred. The
likely hood of cross will produce a
particular type of offspring
Probability
• Percentage- way of expressing a number
as a fraction of 100
• Ratio- expression that compares quantities
relative to each other
• What is the % of heterozygous offspring?
• What is the ratio of
heterozygous to
purple flowers?
Co-Dominance
• With codominance, a cross between
organisms with two different phenotypes
produces offspring with a third phenotype
in which both of the parental traits appear
together.
Incomplete Dominance
•
With incomplete dominance, a cross
between organisms with two different
phenotypes produces offspring with a third
phenotype that is a blending of the
parental traits.
Polygenic
• Means multiple alleles coding for a single
gene.
• Ex- hair color
Epistasis
• When the affects of one gene suppress
the expression of another gene
Sex linked
• Sex linked genes is the phenotypic expression
of an allele that is related to the chromosomal
sex of the individual. This mode of inheritance is
in contrast to the inheritance of traits on
autosomal chromosomes, where both sexes
have the same probability of expressing the trait.
Since, in humans, there are many more genes
on the X than there are on the Y, there are many
more X-linked traits than there are Y-linked
traits.
Multiple alleles
• Although any individual has at most two
different alleles, most genes exist in a
large number of allelic forms in the
population as a whole. In some cases, the
alleles have different effects on the
phenotype, and their dominance
interactions with each other can be
described as a series.
Blood System
• For example, the best known human blood
groups, the ABO system, comprises three
sets of alleles at the I locus, IA, IB, and IO.
The first two are dominant to the latter:
that is, the AA and AO genotypes produce
indistinguishable blood group phenotypes,
called “Type A”, as do BB and BO, which
produce “Type B” blood.