Part 1: Genes, Chromosomes, and Heredity
chose the garden
as his model system because it grows easily to maturity in one season, and can be
Mendel examined seven visible
(traits), each with two contrasting
, using true-breeding parental strains.
These crosses are called
since they involve a single pair of contrasting traits. These crosses are also
since the sex of the parents did not affect the outcomes.
generation, and their offspring are the
generation. Offspring arising from
(self-fertilizing) the F
generation are the
To explain the results of his monohybrid crosses, Mendel proposed three postulates that form the basis for Mendelian or
Traits are inherited in
factors (genes) which exist in pairs.
One form of each unit factor is
for the trait and the other is
The paired unit factors
(separate) independently during gamete formation.
is the genetic makeup of an individual. The
is the physical expression of the genotype.
Alternative forms of a
. If the two alleles for a
in an individual are the same, the individual is
, otherwise the individual is
is a tool to analyze and predict the ratios of
of a monohybrid
with a homozygous
individual can be used to determine whether an organism displaying the
is homozygous or heterozygous for that trait.
involves two pairs of contrasting
Mendel proposed a
postulate from his dihybrid
during gamete formation.
are based on probability, and simple
and laws of
can be used to find various combinations in crosses.
The probability of allele
of allele frequencies in the
The frequency probabilities of multiple allele
of the frequency probabilities of the individual alleles.
shows a family
with respect to a
and is a valuable tool in human genetic
Mendel's principles of independent
can be explained by the modern
that occur during
Oct 2, 2008