Download or Rr

What does pedigree mean?
Pedigree: a diagram that traces one trait
through several generations of a family
= female
= male
Example #1
3
How many girls? ___
2
How many boys? ___
mom
daughter #1
dad
daughter #2
son
mom
dad
oldest
daughter #1
youngest
daughter #2
son
A horizontal line connecting two
shapes represents a cross/marriage.
mom
dad
Example #2
How many crosses/marriages?
2
A
C
B
D
E
F
G
A vertical line extending down from a
marriage/cross represents that the
couple has children.
mom
dad
A
C
B
D
questions…
E
F
G
Example #3
A
C
How many couples
have children?
B
D
H
H
G
E
F
M
J
N
K
L
O
?
P
Q
R
S
T
4
How do you show twins?
A
C
B
D
E
F
How do you show traits? Shading
( shaded = recessive )
RR
Rr
rr
mutation
**A pedigree chart follows one trait.
Rr
mom
RR
dad
R = tongue roller
r = non-roller
Rr
son
Rr
daughter
RR
daughter
R
R
R
RR
RR
r
Rr
Rr
A
C
B
D
G
E
F
M
Practice
questions…
J
N
P
HH
K
L
O
Q
R
S
T
What is wrong
with this
pedigree chart?
This offspring
cannot receive 2
recessive genes.
This offspring cannot
receive 2 dominant genes.
This offspring
cannot receive 2
recessive genes.
What are
possible
genotypes for
individual W?
W
R
r
R
RR
Rr
r
Rr
rr
W could be RR (no shading)
or Rr (half-shaded) or rr (all
shaded).
Pedigree charts help to trace
genetic diseases. Most genetic
diseases are a recessive gene.
Info to
help you
with
page 93
If you have 1 recessive, you are a
carrier, but you are not sick.
Aa
If you have 2 recessive genes, you
are sick with the disease. (you are
“affected”)
aa
4
3
Granddaughter, carrier, 3rd generation, older sibling
Grandson, carrier, 3rd generation, middle sibling
rr
Rr
1
7
A person that carries one copy of the disease gene, but it
is masked by the dominant trait. (hybrid)
2
U
U is further left. This makes U older than V
Genetic Pedigree Answers
4
1.
How many children did the first generation have?
2.
How many girls did the first generation have?
3.
Describe individual Y.
A female carrier/hybrid
4.
Describe individual Z.
A male carrier/hybrid
5.
How many children and grandchildren have the disease?
6.
What is the genotype of X? Use the letter R/r.
7.
What is the genotype of Y? Use the letter R/r.
8.
How many children and grandchildren are carriers for the disease?
9.
10.
11.
3
1
rr
Rr
7
Shows the dominant trait, but can pass the
What is a carrier?
recessive gene on to offspring.
How many kids did W and his wife have?
2
U
Who is older, U or V?
It comes first left to right
How do you know?