When Heredity Does Not Follow Mendelian Rules. Complex Patterns of Heredity Incomplete Dominance RR R' RR RR Neither phenotypes is completely dominant.
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When Heredity Does Not Follow Mendelian Rules
Complex Patterns of HeredityIncomplete Dominance
R R
R'
R' RR
RR
R'R'
R'R'
Neither phenotypes is completely dominant
R = RedR = Red
RR'' = White = White
RRRR'' = Pink = Pink
RR = RedRR = Red
RR''RR'' = White = White
Incomplete Dominance
R
R
R'
R’
R
R
RR
R'R'
R'
R'
Neither phenotypes is completely dominant
R = RedR = Red
RR'' = White = White
RR = RedRR = Red
RR''RR'' = White = White
RRRR'' = Pink = Pink
Codominance
Both possible phenotypes can be expressed
R
R
R'
R’
R
R
RR
R'R'
R'
R'
Both phenotypes are expressed in heterozygotes
R = RedR = RedRR'' = White = White
RR = RedRR = Red
RR''RR'' = White = White
RRRR'' = Spotted = Spotted StripedStriped CheckeredCheckered Etc.Etc.
Multiple Phenotypes from Multiple AllelesTraits controlled by multiple alleles
B
b
B
b
B
B
bB
bb
b
B
B = Blue FeathersB = Blue Feathers
b = Chocolate Feathersb = Chocolate Feathers
BBAA = Ash-red Feathers = Ash-red Feathers
B dominant to bB dominant to b
B recessive to BB recessive to BAA
b recessive to Bb recessive to B
b recessive to Bb recessive to BAA
Multiple Phenotypes from Multiple AllelesTraits controlled by multiple alleles
BA
b
B
b
B
BA
bBA
bb
b
B
Multiple Phenotypes from Multiple AllelesTraits controlled by multiple alleles
BA
B
B
b
B
BA
BBA
bb
B
B
Multiple Phenotypes from Multiple AllelesTraits controlled by multiple alleles
BA
BA
b
b
BA
BA
BABA
bb
b
b
Sex Determination22 Pairs of Homologous Chromosomes: Autosomes
X
X
Y
X
X
X
XX
YX
Y
X
1 Pair of Sex Chromosomes
Sex Linked InheritanceTraits located on sex chromosomes: Sex-linked
traits
Xr
XR
Y
XR
XR
Xr
XRXr
YXR
Y
XR
XXRR = Red Eyes = Red Eyes
XXrr = White Eyes = White Eyes
Males = ½ Red EyesMales = ½ Red Eyes
Males = ½ White EyesMales = ½ White Eyes
Females = All Red EyesFemales = All Red Eyes
Polygenic InheritanceTraits controlled by multiple genes
AA BB CC
AA BB CC
aa bb cc
aa bb cc
AAAABB BB CCCC AAaaBB bb CC cc
AAaaBB bbCCcc aaaa bb bb cc cc
Sickle-Cell Disease
H
H'
H
H’
H
H
H'H
H'H'
H'
H
Codominance
Sickle-Cell Disease
H
H'
H’
H'
H'
H
H'H
H'H'
H'
H'
Sickle-Cell Disease
H
H’
H’
H’
H’
H
H’H
H’H’
H’
H’
Multiple Alleles and Blood Type
Multiple Alleles and Blood Type
Multiple Alleles and Blood Type
Sex-Linked Traits in Humans
Color Blindness
XR XG
XR XG
Xr Xg
Y
XR XG XR XG
XR XG Xr Xg Xr Xg
Y
Y
XR XG
Sex-Linked Traits in Humans
Hemophilia: 1:10,000 males1:100,000,000 females
XH
Xh
Y
XH Y
Y
XH
XH Xh Xh
XH
XH
Sex-Linked Traits in Humans
Hemophilia: 1:10,000 males1:100,000,000 females
Xh
Xh
Y
XH Y
Y
Xh
XH Xh Xh
Xh
XH
Sex-Linked Traits in Humans
Hemophilia: 1:10,000 males1:100,000,000 females
Xh
Xh
Y
XH Y
Y
Xh
XH Xh Xh
Xh
XH
Sex-Linked Traits in Humans
Hemophilia: 1:10,000 males1:100,000,000 females
Xh
Xh
Y
Xh Y
Y
Xh
Xh Xh Xh
Xh
Xh
Changes in Chromosome Numbers in Humans
46
23 23
Meiosis, Anaphase (normal)
Changes in Chromosome Numbers in Humans
46
23 23
Fertilization
Normal
Changes in Chromosome Numbers in Humans
46
24 22
Meiosis, Anaphase
Down Syndrome: Trisomy 21
Changes in Chromosome Numbers in Humans
47
24 23
Fertilization
Changes in Chromosome Numbers in Humans
45
22 23
Fertilization
Abnormal Number of Sex Chromosomes
Sex Determination22 Pairs of Homologous Chromosomes: Autosomes
X
XX
Y
XXX
YX
Y
Result of Non-disjunction
X X
Trisomy(21) Down Syndrome
Monosomy: Turner Syndrome
Hexapoid: Wheat
Trisomy(13) Patau’s Syndrome
Triploid: Apples
Polyploid: chrysanthamums
Tool of Genetics
Punnett Square
Pedigree
Karotype
DNA Fingerprinting
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