Transcript Pedigree Video Clip What is a pedigree?

Pedigree Video Clip
What is a pedigree?
• A pedigree is a family tree that shows the
inheritance of a trait
How do you read a pedigree?
• Squares represent
males
• Circles represent
females
• A horizontal line
connecting the male
and female indicates
marriage
• Children are connected
to a vertical line
How do you read a pedigree?
• An individual who is
shaded in has the trait I
in question
1
• Each row indicates a
generation
2
II
• Individuals in a row are
numbered from left to
right
1
2
3
How do you read a pedigree?
• Each individual is
referred to by the
I
generation number and
where they are located
in the row
• Which individuals have
II
the trait? I-1 and II-2
1
1
2
2
3
How do you read a pedigree?
• Some individuals may
be carriers or
heterozygous for a trait
• These individuals may
be represented with a
half shaded symbol;
however, sometimes it
is not shaded in at all
Determining inheritance patterns of Pedigrees
• Dominant inheritance– Trait appears in every generation
– Many individuals have the trait
• Recessive inheritance– Trait skips generations
– Few individuals have the trait
• Sex-linked inheritance– More males have the trait than females
– Can be dominant or recessive
Problem #1
• Which individuals have
the trait? I-1, II-1, II-5, II-8, III-1, III-6, III-8
• What is the inheritance
pattern? dominant
• What is the possible
genotype of individual
II-3? hh
Problem #2
• Which individuals have
the trait? I-1, III-2
• What is the inheritance
pattern?
Sex-linked, recessive
• What is the possible
genotype (s) of individual
I-2? XHXH or XHXh