Unit 3: The Continuity of Life
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Chapter 11
Foundations of Genetics
Review
Gregor
Mendel
studied inheritance in the
garden
.
In Mendel's experiments, the F
2
generation plants of a
cross
exhibited 3/4
to 1/4
ratio.
Mendel's theory of
explains these observations: traits are inherited from parent to offspring as "factors" now known as
genes
that can be of different versions called
, one
allele
inherited from each parent.
A
Punnett
can be used to predict the
distribution
of
and
of offspring of a
cross.
Dihybrid crosses show that genes located on different
exhibit
independent
: the genes are inherited independently of each
other.
A
with a homozygous
individual can be used to
determine
the genotype of a
individual.
Mendelian genetics review:
Many traits exhibit non-Mendelian inheritance.
Some traits are
and exhibit
variation
which results from the action of multiple genes.
dominance
results when alternative alleles are not fully dominant or fully recessive; the heterozygote phenotype is
between that of the homozygotes.
The human
ABO
blood group is controlled by
alleles and also exhibits
.
Some genes is also influenced by
factors,
such as photoperiod.
Morgan
showed that traits like eye color in fruit flies are
-
linked;
in this case the eye-color gene resides on the
chromosome.
may occur during meiosis, resulting in gametes with incorrect number of
chromosomes,
or
.
Aneuploidies include
trisomy
21, which causes
syndrome, and sex chromosome
aneuploidies.
can be used to track the
inheritance
of genetic disorders, such as
sickle-cell
and
Huntington's
disease.
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Mar 14, 2010
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