Download Punnett Squares

GENOTYPES,
PHENOTYPES, AND
PUNNETT SQUARES
GENOTYPE VS.
PHENOTYPE
An
organism’s genotype is its
genetic makeup (allele
combination).
 Ex:
TT, Tt, tt
An
organism’s phenotype is its
physical appearance.
 Ex:
TT = Tall, Tt = Tall, tt = short
ALLELE COMBINATIONS
When
it comes to genotypes
(allele combinations), there are
two types:
 Homozygous
 Heterozygous
HOMOZYGOUS
Homozygous
means that the
organism only has one type of
allele for a trait. (Purebred)
 Ex:
TT, tt, BB, bb
HETEROZYGOUS
Heterozygous
means that the
organism has multiple alleles for
a trait.
 Ex: Tt, Bb
PUNNETT SQUARES
A punnett square is a diagram
used to predict the outcome of a
breeding experiment.

AA
a
A
Aa
A
Aa
a
Aa
Aa
aa
TT = Blue Tail
OCEAN & LUCY
Tt = Blue Tail
Ocean
tt = Orange Tail
(Tt = Heterozygous)
T
t
T
TT
Tt
t
Tt
tt
Lucy
(Tt)
(Locean)
Locean & Sandy
Locean
(tt = Homozygous Recessive)
Sandy
(Tt)
T
t
t
t
Tt
Tt
tt
tt