Download Simple or Complex Inheritance Patterns Sex

Simple or Complex
Inheritance Patterns
"Simple vs. Complex Traits”: the real definition
Simple: things we have deluded ourselves into
thinking we understand
Complex: things we're pretty sure we don't
understand." Eleanor Feingold, Department of Human Genetics, University of
Pittsburgh: On the changing definition of simple (Mendelian) versus complex traits
Some Alleles Are Related
Through Incomplete
Dominance
What are the other patterns of
inheritance?
Incomplete Dominance- What happens when
neither allele is dominant?
• intermediate phenotype.
• This occurs when neither allele in a hybrid is
completely or not completely expressed, such
that neither allele can mask the other allele
Multiple Alleles
Many genes are present in 3
or more versions (alleles) –
this is known as multiple
alleles.
The human ABO blood
group is determined by three
alleles (IA, IB, and i) of a
single gene.
Dominance relationships may
differ, but the Principle of
Segregation remains the same.
Codominance
The human ABO blood
group illustrates another
genetic phenomenon –
codominance.
Codominance occurs when
the phenotype associated
with each allele is expressed
in the heterozygote.
Sex-Linked Traits
 Specifically genes
coded for on the
chromosome
X
 Unrelated to gender
The AB
phenotype
(genotype IA
IB ) is an
example of
codominance
 Can dad pass this to
his sons? What
about mom?
Explain.
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Pleiotropy – When One Allele Influences
Many Traits
Pleiotropy in
Action
Anemia,
infections,
weakness,
impaired
growth, liver
and spleen
failure,
death.
Traits (phenotypes)
associated with the
sickle cell allele.
Polygenic Inheritance – When a Single Trait
is Influenced by Many Genes
The importance of
Mendel’s work
 Mendels Laws apply to all diploid
organisms including humans.
 His work enables humans to predict the
inheritance of a number of inherited
diseases like cystic fibrosis.
 His careful and systematic work forms
the basis of all heredity
Height is a
polygenic trait
What are the implications of current and
emerging biomedical, genetic, and
reproductive technologies?
genetic probes
genetic testing
gene therapy
cloning
biomedical,
genetics, and
reproductive
technologies
forensic science
drug development
drug production
GMOs
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