Transcript Pedigrees - lovettlifescience

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Pedigrees
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What is a Pedigree?
A) A type of dog food.
B) A direct heir from a super rich family.
C) A diagram of familial relationships that uses symbols to
represent people and lines to represent genetic
relationships.
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Why use a pedigree?
A) They make it easier to see the relationships
between family members.
B) They can help a family to see how and to whom
genetic traits have been passed.
C) Both A and B are correct.
D) It is a good brand of inexpensive healthy dog
food.
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Symbols used in Pedigrees
Heterozygous for
autosomal recessive
Carrier sex-linked
recessive
Deceased
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Types of Pedigrees
There are 2 types of pedigrees:
1.Autosomal:
Traits that are located on the non-sex
chromosomes, Pairs 1-22.
These traits can be inherited through the dominant form or the
recessive form.
Pedigrees will look different depending on the trait inherited -recessive or dominant.
2.Sex-linked: Traits that are located on the sex
chromosomes, X or Y.
*Carrier symbols are only used in sex-linked pedigrees.
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The Rules, cont.
3. For dominant and recessive traits, people who HAVE the trait
being analyzed ALWAYS have fully shaded in symbols.
*Sex-linked traits use the carrier symbol.
4. Alleles are assigned using the first letter of the trait as follows:
(using tongue rolling as an example)
For Autosomal Dominant Traits:
T = affected
(or CAN roll tongue)
t = normal
(or CANNOT roll tongue)
** A shaded in symbol could be homozygous dominant, heterozygous, or
homozygous recessive!
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The Rules, cont.
L@@K:
For Autosomal Recessive Traits:
(using Albinism as an example)
A = not affected
(not albino)
a = affected
(albino)
* A shaded in symbol will only be homozygous recessive!
5. Always use a key!
List the trait and the symbol to be used.
See examples—Tongue Rolling and Albinism.