Download Pedigree It`s more than just a dog food!

PedigreesWorking Out
Inheritance Patterns
Genology - Lee Family of Virginia and Maryland
c1886 Apr. 26.
Prints and Photographs Division,
Library of Congress (LC-USZ62-90145)
BioEd Online
Punnett Squares
• an accurate way to predict the possible
characteristics in the offspring of two
known parents.
But a Pedigree…
It’s more than just a dog food!
Pedigree
a diagram of family relationships
that uses symbols to represent
people and lines to represent
genetic relationships.
Pedigrees
• make it easier to visualize
relationships within families,
particularly large extended
families.
Pedigrees
• are often used to determine the
mode of inheritance (dominant,
recessive, etc.) of genetic
diseases.
Pedigrees
• are used to represent the
presence of certain traits through
a family and provide a picture of
several generations of
inheritance.
Pedigrees
• Information gathered through
several generations, including
aunts, uncles, cousins, and
grandparents, give a more
complete picture of inheritance of
particular traits and give a better
understanding of the inheritance
of certain disorders.
Pedigree Diagrams: I
• Basic Symbols
BioEd Online
Pedigrees
• squares represent males and
circles represent females.
Horizontal lines connecting a
male and female represent
mating. Vertical lines extending
downward from a couple
represent their children.
Pedigrees
• Every generation is represented by a
Roman numeral, and each member of the
generation by an Arabic numeral.
Pedigrees
• the purpose of a pedigree is to
analyze the pattern of inheritance
of a particular trait
• The grandparents had two children, a son
and a daughter.
• The son had the trait in question. One of
his four children also had the trait.
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II
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2
III
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2
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4
Hemophilia: An Example
• In this pedigree, only males are
affected, and sons do not share the
phenotypes of their fathers.
– Thus, hemophilia is linked to a sex chromosome–the X.
• Expression of hemophilia skips
generations.
– Thus, it is recessive.
BioEd Online
Extensive bruising of
the left forearm and
hand in a patient with
hemophilia.
Half of My Sons’ pedigree
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