Unit 3: Genetics
Animations
Study Guide
Chapter 14
Mendel and the Gene Idea
Review
Gregor
Mendel
studied the
of several characters with
peas.
Mendel proposed "heritable
" to explain his results based on two principles of inheritance.
Law of
.
Mendel's "heritable factors" are now known to be
genes,
which have alternative versions called
.
The
allele determines a heterozygous individual's
appearance,
or
.
The two alleles
in meiosis, and the distribution of the segregated phenotypes can be calculated from a
model called the
square.
How can we determine the genotype of an organism with the dominant
? A
testcross
with an individual that is homozygous
for the trait.
Monohybrid Cross activity
Law of Independent
.
Crossing true-breeding parents differing in
two
characters produces
in the F1 generation heterozygous for both characters, and
phenotypes in the F2 generation.
Dihybrid Cross activity
Mendel's laws are based on probability. In a
cross, the probability of allele
frequencies
in the zygote is the
of the probabilities of allele frequencies in the
.
Review: Mendelian Genetics activity
Extending Mendelian Genetics.
In
dominance,
the
of
is somewhere between the phenotypes of homozygotes.
Incomplete Dominance activity
In
, two dominant alleles affect the
phenotype.
Some traits exhibit
inheritance which often shows
variation.
In
, a gene at one
may alter the phenotypic expression of a gene at a second locus. An example is the mouse coat
color.
Inheritance in human families can be studied by analyzing a
showing the inheritance of alleles across
generations.
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