Genetics ProblemsMonohybrid Dihybrid

Selected Traits In CatsTrait Dominant Allele Recessive Allele

Coat Length

Short hair(H)

Long hair(h)

Tabbystripes

Tabby(T)

Stripeless(t)

Markings Normal (no colorpoint)(N)

Colorpoint(n)

Coat Length

Short Hair Long Hair

Tabby Stripes

Tabby Stripeless

Markings

Normal (no colorpoint) Colorpoint

Cats #1Heterozygous short-hair x Heterozygous short-hair Hh x Hh

H

H

h

h

HH Hh

Hh hh

Genotypic ratio:

Phenotypic ratio:

1HH : 2Hh : 1hh

3 Short Hair: 1 Long Hair 0r

75% short Hair: 25% Long Hair

Cats #2Heterozygous Tabby x StripelessTt x tt

T

t

t

t

Tt tt

Tt tt

Genotypic ratio:

Phenotypic ratio:

2Tt : 2 tt or 50% Tt : 50% tt

2 Tabby : 2 Stripeless 0r

50% Tabby: 50% Stripeless

Cats #3Colorpoint x Homozygous Normalnn x NN

n

N

n

N

Nn Nn

Nn Nn

Genotypic ratio:

Phenotypic ratio:

4 Nn or 100% Nn

4 Normal markings 0r

100% Normal markings

Cats #4Homozygous short/homozygous colorpoint x

homozygous long/ homozygous normal HHnn x hhNN

HhNnhN

hN

hN

hN

Hn Hn Hn Hn

16 - Short hair

Normal markings

Or

100% - Short hair

Normal markings

HhNn

Phenotypes

HhNn

HhNn

Cats #5Heterozygous Short/heterozygous normal x

Heterozygous Short/heterozygous normal HhNn x HhNn

HHNN

HN Hn hN hn

9 Short/Normal

3 Short/Colorpoint

3 Long/Normal

1 Long/Colorpoint

HHNn

HhNN

HhNn

Phenotypes

HN

Hn

hN

hn

HHNn

HHnn

HhNn

Hhnn

HhNN

HhNn

hhNN

hhNn

HhNn

Hhnn

hhNn

hhnn

Cats #6Heterozygous Tabby/heterozygous normal x Stripeless/colorpoint

TtNn x ttnn

TtNn

tn

tn

tn

tn

TN Tn tN tn

4 Tabby/Normal

4 Tabby/Colorpoint

4 Stipeless/Normal

4 Stripeless/Colorpoint

Ttnn

ttNn

ttnn

Phenotypes

Cats #7 Long-hair/heterozygous normal x Long-hair/heterozygous normal

hhNn x hhNn

hhNN

hN

hn

hN

hn

hN hn hN hn

Long-hair

Normal

Long-hair

Colorpoint

hhNn

hhNN

hhNn

Phenotypes

hhNn

hhnn

hhNn

hhnn

hhNN

hhNn

hhNN

hhNn

hhNn

hhnn

hhNn

hhnn

12

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