Transcript 14.1 Pedigrees File

Ch.14-1
Pedigrees
POINT > Describe pedigree analysis
POINT > Describe symbols used in pedigrees
POINT > Demonstrate an autosomal disorder
pedigree
POINT > Demonstrate a sex-linked disorder
pedigree
POINT > Describe pedigree analysis
A pedigree is a chart to trace phenotypes &
genotypes within a family
Useful to help to determine inheritance of recessive
alleles (as potential carriers of disorders)
POINT > Describe symbols used in pedigrees
Pedigrees use symbols to show information:
Square = male
Circle = female
Blank figure = normal
Male
Female
POINT > Describe symbols used in pedigrees
Pedigrees uses symbols to show information:
Filled in shape = has the disorder/trait
Male
Female
POINT > Describe symbols used in pedigrees
Pedigrees use symbols to show information:
Half-filled shape = carrier
Male
Female
POINT > Describe symbols used in pedigrees
Pedigrees use symbols to show information:
Roman Numerals indicate generation
I
POINT > Describe symbols used in pedigrees
Pedigrees use symbols to show information:
Lines show relationships
Horizontal line directly between symbols
indicates a mating relationship
I
POINT > Describe symbols used in pedigrees
Pedigrees use symbols to show information:
Vertical line shows offspring from mating
relationship
Multiple offspring noted by branching line
I
II
WB CHECK:
This symbol represents
a) a male that is homozygous dominant
b) a female that is a carrier
c) a male that has the trait/disorder
d) a male that is a carrier
e) a male that is homozygous recessive
WB CHECK:
These symbols represent
a) two carriers that are brother and sister
b) a mating couple that both have the trait/disorder
c) a mating couple that are both carriers
d) a brother and sister that both have the trait/disorder
POINT > Demonstrate an autosomal disorder pedigree
If a trait/disorder is autosomal, males &
females are affected equally
Both sexes can be carriers for recessive traits
If a trait is dominant, can someone be a
carrier?
POINT > Demonstrate an autosomal disorder pedigree
I
Ss
ss
Sickle-cell anemia
is autosomal recessive
II
SS
Ss
Ss
SS
Ss
Ss
ss
III
ss
Ss
SS
POINT > Demonstrate an autosomal dominant
pedigree
I
ww
Ww
ww
Ww
ww
Ww
ww
Widow’s Peak is
autosomal dominant
II
Ww
Ww
WW
or Ww
ww
III
Ww
POINT > Demonstrate a sex-linked disorder
pedigree
If a trait/disorder is sex-linked, males &
females are affected differently
Males cannot be carriers for X-linked
recessive traits (but females can be)
Again, no carriers for dominant traits
POINT > Demonstrate a sex-linked disorder pedigree
I
XB Y
XBXb
Color blindness is
X-linked recessive
II
XbY
XBXb
XBXB
XbY
Xb Y
XBXB
XBXb
XBY
III
XbXb
XBY
XBXb
Xb Y
WB CHECK:
This pedigree represents a trait/disorder that is
a) autosomal dominant
b) autosomal recessive
c) sex-linked recessive
d) sex-linked dominant
Homework:
Read pages 392-397
Assess #1-3 page 397
Workbook pages 186-188
Punnett Squares 2
Pedigree Worksheet 1