Download one length from each parent

Chromatin in a Normal Cell
(one length from each parent)
F
Free
Earlobe Gene
f

Allele

Attached 
Dominant

a
Melanin Gene
Albino
P
Extra
Fingers
a

albino
Polydactyly Gene
♂
P
Extra
Fingers
♀
Allele that may be masked
by another
Heterozygous


Allele that may mask the
presence of another
Recessive


A version of a gene
The 2 alleles are different
Homozygous

The 2 alleles are identical
Chromatin in a Normal Cell
(one length from each parent)
F
Free
Earlobe Gene
f


attached

a
Melanin Gene
albino
P
Extra
Fingers
a
albino
Polydactyly Gene
♂
P
Extra
Fingers
♀
Genotype
The set of alleles an
organism possesses
Phenotype

The genetic outcome
resulting from the genotype
Inheritance
f
f
f
f
f
F
F
f
F
F
F
F
Exact copies
Pure bred parents
PP
P
x
pp
p
P
p
What will the F1 offspring look like?
Phenotype = 100% Purple
Genotype = 100% Heterozygous
P
p
What will the F2 offspring look like?
Phenotype = 75% Purple 25% white
Genotype = 100% Homo. Dominant,
50% Hetero., 25% Homo. Recessive
Dihybrid Cross
GgYy
GY
Gy
gY
gy
GY
GGYY
GGYy
GgYY
GgYy
Gy
GGYy
GGyy
GgYy
Ggyy
gY
GgYY
GgYy
ggYY
ggYy
gy
GgYy
Ggyy
ggYy
ggyy
PHENOTYPE
G-Y- : 9
G-yy : 3
ggY- : 3
ggyy : 1
Law of segregation: two
alleles for a trait separate
when gametes are formed
Law of Independent
assortment:
Alleles of different genes
separate independently of
one another during
gamete formation
Codominance


Both alleles are detectable in a specimen
Gene:
Cattle coat color
Alleles
CR = red
CW = White
Genotypes
C RC R
= red coat
CWCW
= white coat
C RC W
= roan coat
Multiple Alleles


More than two alleles exist for a gene
Human Blood Type
 A


I
IB
i
= Type A carbs on RBC surface
= Type B carbs on RBC surface
= Neither type on RBC surface
Multiple Alleles
Blood Type
Genotype
Antibodies
Universal Acceptor
Universal Donor
Linked Genes
Polygenic
Chrom.15
Chrom.19

Dominance
Brown over
 Blue over
 Green
Sex linked: traits are tied to X or Y
r
Y
X
R
X
R
X
R
r
X Y
R
r
R
X X
X X
R
X Y
X
R
X
r
X
R
Y
R
X XR XR Y
r
R
X X
r
X Y
Sex linked: traits are tied to X or Y
Color blindness:males
Recessive xrlinked Y
X
Abnormal production
of pigment(protein)
R
R r
R
Does
redY
X notXabsorb
X X
green light
R
X
R
r
X X
R
X Y
X
R
X
r
X
R
Y
R
X XR XR Y
r
R
X X
r
X Y
Sex influenced

Trait not tied to sex chromosome
Autosomal chromosome produces protein which
affects the production of other proteins.
 Testosterone affects
the production and
location of hair in males.

Patterns of Inheritance
Polygenic: Eye color, skin color, height
Complex characters: Skin color=sun,
Multiple alleles: Blood type
Incomplete Dominance: Red x White= Pink
X-linked: Color blindness, fruit fly eyes
Sex influenced: Male pattern baldness
Single alleles: Huntington’s disease,