Transcript Mendel`s genetics

Page 88, Dihybrid Problems #2
In rabbits, black coat color is due to a dominant
gene B, brown coat color is due to a recessive
gene b. Short hair is due to a dominant gene S,
long hair to its recessive allele s. In a cross
between 2 heterozygous black, short haired
rabbits, what would be the phenotypic ratio of
the offspring?
1
B – black coat
S – short hair
b – brown coat
s – long hair
Cross between 2 heterozygous
black, short haired rabbits
B
bSs
Ss
BbSs
x BbSs
BS Bs bS bs
2
#1 Results
BS
Bs
bS
bs
BS
BBSS
BBSs
BbSS
BbSs
Bs
BBSs
BBss
BbSs
Bbss
bS
BbSS
BbSs
bbSS
bbSs
bs
BbSs
Bbss
bbSs
bbss
3
B – black; b – brown; S – short; s - long
BS
BS
Bs
bS
bs
BBSS
BBSs
BbSS
BbSs
Black (B), short (S)
Black (B), long (s)
Bs
bS
bs
BBSs
BbSS
BBss
BbSs
BbSs Bbss
BbSs
Bbss
bbSS
bbSs
bbSs
bbss
Brown (b), short (S)
Brown (b), long (s)
9:3:3:1
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Page 88, Dihybrid Problems #2
In horses, black color is dependent upon a
dominant gene B, and chestnut upon its
recessive allele b. The trotting gait is due to a
dominant gene T and the pacing gait to its
recessive allele t. if a homozygous black pacer
is mated to a homozygous chestnut trotter,
what will the genotype and phenotype of the F1
generation be?
5
B – black
T - trotting
Homozygous x
black pacer
BBtt
x
Bt Bt Bt Bt
b – chestnut
t – pacing
Homozygous
chestnut trotter
bbTT
bT bT bT bT
6
B – black; b – chestnut; T – trotting; t - pacing
Bt
bT BbTt
bT BbTt
bT BbTt
bT BbTt
Bt
Bt
Bt
BbTt
BbTt
BbTt
BbTt
BbTt
BbTt
BbTt
BbTt
BbTt
All offspring
BbTt
—
Black Trotters
BbTt
BbTt
BbTt
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Page 88, Dihybrid Problems #3
If two F1 individuals from #3 were mated, what
would be the phenotypic ratio of the offspring?
BbTt
BT Bt bT bt
x
BbTt
BT Bt bT bt
8
B – black; b – chestnut; T – trotting; t - pacing
BT
BT BBTT
Bt BBTt
bT
Bt
bT
BBTt BbTT
bt
BbTt
9:3:3:1
BBtt
BbTt
Bbtt
BbTT BbTt
bbTT
bbTt
bbTt
bbtt
bt BbTt
Bbtt
9
Page 88, Dihybrid Problems #4
An organisms has the genotype AABb. It is
crossed with an individual with the genotype
Aabb. What type of gametes can be produced
by these two individuals?
AABb
AB Ab AB Ab
x
Aabb
Ab Ab ab ab
10