TEACHER KEY
Punnett
Basics
Watch
video of a
Sample
Punnett
Square
Problem
being
solved
3
GENE
ALLELE
GENOTYPE
PHENOTYPE
HOMOZYGOUS
3
HETEROZYGOUS
DD
Rr
bb
CC
Ww
tt
GG
Pp
nn
Hh
4
Tt
tt
TT
pp
5
Pp
PP
rryy
RRYY
RRYy
RRyy
rrYy
6
RrYy
RrYY
Rryy
rrYY
7
GGii
Ggii
ggIi
ggII
GgII
GGII
GgIi
GGIi
ggii
Watch
video of a
Sample
Punnett
Square
Problem
being
solved
8
Tt
T
t
t
Tt
tt
50%
t
Tt
tt
50%
tt
4
9
Bb
Bb
100%
Bb
Bb
0%
B
B BB
Bb
75%
Bb
bb
25%
b
10
b
Bb
B
b
b
Bb
bb
50%
b
Bb
bb
50%
bb
11
N
12
n
n
Nn
nn
50%
n
Nn
nn
50%
Nn
N
n
N NN
Nn
100%
N NN
Nn
0%
NN
13
NN
Nn
ett
Punn
d
e
t
ple s that a
com
This are show t Father
n
Squ
0%
mina
o Do duce 10 .
m
o
o
H
r
n
i
p
pr g
ld
wou rns offs
o
No H
N
The father is most likely Homozygous
Dominant (NN) which would always produce
offspring with No Horns. A heterozygous father
would have a 50% chance of producing horns,
so offspring with horns would appear with a
large enough sample size.
5
NN
N
n
Nn Nn
n
Nn Nn
nn
Hh
H
h
h Hh hh
50%
hh
h Hh hh
14
50%
ff
f
Probability
of Black Fur
f
100%
F Ff
Ff
F
Ff
FF
15
Ff
Probability
of Yellow Fur
0%
FF
If the father were homozygous dominant,
he could only “give” the “F” allele to
offspring. This would mean all offspring
would have at least one “F” and could not
have yellow fur which needs “ff.”
16
FF
Ff
F
F
f
Ff
Ff
f
Ff
Ff
ff
9
17
3
3
1
1
6
1
1
1
Rryy
Rryy
Rryy
rrYy
rrYy
rrYy
rryy
rryy
rryy
9
7
3
3
1
RRYY
RRYy
RrYY
RrYy
RRYy
RRyy
RrYy
Rryy
RrYY
RrYy
rrYY
rrYy
RrYy
Rryy
rrYy
rryy
●
●
●
●
●
●
●
●
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Worked with pea plants because they are true breeding
Found that parents pass traits to offspring
Deduced that genes come in pairs, one from each parent
Found that traits could “skip” a generation
Explained the principle of dominance
Developed Law of Segration
Developed Law of Independent Assortment
Known as the Father of Genetics
RR
19
RW
WW
R
50%
20
R
R
RR RR
W
RW RW
25%
21
R
W
R
RR
RW
W
RW WW
R
9
50%
50%
R
W
RW RW
W
RW RW
W
100%
22
W
R
RW RW
R
RW RW
W
0%
23
W
R
RW RW
W
WW WW
50%
A B
I I
I
A
I I
A
A
I I
B
B
I I
B
12
A
I i
ii
B
I i
I
A
A A
I I
I
A
A
I
B
0%
A
A
I I
I I
A
B
A
I I
A
I I
A
B
50%
0%
25%
A
I i
I
A
I I
A
A
I I
B
B
I I
B
13
A
I i
ii
B
I i
I
B
B
A
i
A
I I
B
B
I i
A
ii
I i
i
25%
I i
25%
25%
50%
A B
I I
I
A
I I
A
A
I I
B
B
I I
B
14
A
I
B
50%
A
I i
ii
B
I i
A
B
i
I i
I i
i
A
B
ii
I i
I i
0%
0%
A B
I I
A
I
i
IA IA
IA IB
IB IB
15
I
A
I
i
IA i
IB i
i
A
IB i
I
B
IA i
ii
IB i
B
ii
I i
No, the baby is NOT
their child. A Type AB
and Type O parent can
only have children that
are Type A or Type B.
Type O would require an
ii genotype and this is
NOT possible from
these parents’ gametes.
Healthy Female
Klinefelter
Syndrome
Down Syndrome
Healthy Male
Edward’s
Syndrome
Turner Syndrome
16
Edward’s
Syndrome
Down Syndrome
Healthy Male
Healthy Female
17
Klinefelter
Syndrome
Turner Syndrome
Cystic Fibrosis is an autosomal recessive disease.
Ff
18
ff
FF
Ff
FF
Ff
ff
A carrier is heterozygous for a recessive
disease having one dominant and one
recessive allele. A carrier does not have
symptoms of the disease, however, they
can pass the recessive allele to
offspring. In a pedigree, a carrier will
appear as Normal (not diseased), but
can produce offspring with the disease
if crossed with another carrier or
homozygous recessive individual.
19
XB Y
XbXb
XB Xb
XB XB
XB Xb XbXb
XB Y
XbY
20
XbY
Xb
XbXb
XbY
XB Xb
XB Y
XB XB
21
X
b
XB
Y
Y
25%
XB
XB Xb
XB Y
Xb
XbXb
XbY
XB Xb
25%
● American Scientist that began working in Genetics in the early 1900’s
● Worked with a team that studied Fruit Flies (Drosophila melanogaster)
● Showed that genes are linked in a series on chromosomes and are
responsible for identifiable, hereditary traits
● Many of the traits he studied were sex-linked
● Awarded the Nobel Prize in 1933
22