Complex Patterns of Inheritance
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Transcript of Complex Patterns of Inheritance
COMPLEX PATTERNS OF INHERITANCE
Incomplete Dominance One allele does not
over shadow the other, they mix together
Use RR, R’R, R’R’ Ex. Carnations
A red carnation mated with a white carnation makes a pink carnation.
Ex. Snapdragons
Ex. Carnations
Cross a red snapdragon with a pink snapdragon:
Phenotypic Ratio:
Genotypic Ratio:
Parental Genotypes:
Cross a red snapdragon with a white snapdragon:
Phenotypic Ratio:
Genotypic Ratio:
Parental Genotypes:
Co-Dominance Both alleles are
expressed equally. One allele does not over shadow the other.
Use HRHR HRHW HWHW
Ex. Roan Cattle Red and white hairs
are present Ex. Some flowers
Cross a roan cow with a roan bull
Phenotypic Ratio:
Genotypic Ratio:
Parental Genotypes:
Sex Linked Traits that are carried on the
X chromosome Females need 2 recessive
copies of the allele to express the trait, if they receive one they are a carrier.
Males only need one copy of the allele to express the trait, this is why sex linked traits are more prevalent in males.
Use X and Y chromosomes with the allele as a subscript to represent the trait
Normal Female XAXA
Carrier Female XAXa
Affected Female XaXa
Normal Male XAY
Affected Male XaY
Cross a carrier female with a normal male
Phenotypic Ratio:
Genotypic Ratio:
Parental Genotypes:
Multiple Alleles & Co-dominance In humans blood type is
controlled by 3 alleles A, B, O
A & B are co-dominant – O is recessive
Type O: OO or ii Type A:
AA / IAIA (homozygous) AO / IAi (heterozygous)
Type B: BB / IBIB (homozygous) BO / IBi (heterozygous)
Type AB AB / IAIB
Blood TypeBlood Type That Can Be
Received
Type of Antigens Present
Type of Antibodies Produced
A ( IA ) A and O A antigens B antibodies
B ( IB ) B and O B antigens A antibodies
O ( i )Universal
DonorOnly O No antigens A and B
antibodies
AB ( IAIB ) Universal Recipient
All types A and B antigens No antibodies
Blood Types
Multiple Alleles Traits that are
controlled by one gene with several different alleles. Ex. Coat color in
Labs is controlled by 4 different alleles, 5 coat colors are possible.
Polygenic Traits Traits that are
carried on more than one gene.
Exs: hair color, skin color, height.
A a C cB b