Transcript PEDIGREES *a chart that shows how a trait and the genes that

PEDIGREES
(12.3)
*a
chart that shows how a trait and the genes that
control it are inherited within a family.
Symbols:
female
male
mate/
marriage
offspring
USES
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helpful in determining carriers (an individual
who carries a recessive trait that is not
expressed).
to determine whether a trait is dominant or
recessive.
to determine whether a trait is heterozygous
or homozygous dominant
to determine whether a trait is sex-linked
Examples of recessive traits
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Tay-Sachs disease
http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm
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Cystic fibrosis
http://www.nhlbi.nih.gov/health/dci/Diseases/cf/cf_what.html
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Albinism
*The allele is preserved in the population
because the carriers are NOT affected.
Examples of dominant traits
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Freckles
Widow’s peak
Polydactyly
Huntington’s disease
http://www.ninds.nih.gov/disorders/huntington/huntington.htm
*In many cases, a person who has inherited a
dominant allele that produces a fatal disorder
is likely to result in an early death…why is
this important?