Transcript Genetics Notes C

11-3 Vocab and Notes
Genetics Unit
Exploring Mendelian Genetics
Independent assortmentIndependent segregation of
genes during the formation of
gamates.
Incomplete dominance
situation in which one allele is
not completely dominant over
another.
Codominance
situation in
which both
alleles of a
gene contribute
to the
phenotype of
the organism.
Multiple alleles
• three or more alleles of the
same gene
Multiple Alleles
• Three or more alleles of the
same gene.
Polygenic Traits
• Trait controlled by two or more
genes
I. Independent Assortment
a. Principle of Independent Assortment:
genes for different traits can segregate
independently during the formation of
gametes.
Independent
Assortment
b.
2-Factor Cross
i. Predicting the genetic
combination of two
different traits crossed
at the same time
ii.Example- Round and
yellow peas crossed
with shriveled and
green peas
2. Incomplete Dominance
a.When the heterozygous
phenotype is somewhere
in between the two
homozygous phenotypes
b.In some cases, no allele
is completely dominant
c. Example- Red flowers
crossed with white
flowers produce pink
flowers
3. Co-dominance
a.When both alleles
contribute to the phenotype
of an organism
b. Example- Cattle alleles for
red hair are co-dominant
with the allele for white
hair, and if both alleles are
present, then the coat color
has a mixture of red and
white hair (roan)
4. Polygenic traits
a. When the trait is controlled by the
interaction of several genes (two or
more)
b. These traits often show a wide range of
phenotypes because of the many allele
combinations
c. Example- Skin color in humans
(controlled by more than 4 different
genes)