Download Complex Inheritance Patterns

Complex Inheritance
Patterns
Kline
Biology
1. Simple Recessive
• Also called “autosomal recessive”
• Trait/Disease is carried on the recessive allele
• Must inherit trait/disease from both parents
• Ex/ Cystic fibrosis
• CC – Normal (not afflicted)
• Cc – Carrier (has the allele for the disease, but no symptoms)
• cc – Afflicted (has the disease)
Simple Recessive
• If two heterozygous carriers for Cystic Fibrosis had a child,
what would be the likelihood that their child would inherit the
disease? Draw a Punnett square and write the probability.
2. Simple Dominant
• Also called “autosomal dominant”
• Trait/Disease is controlled by a dominant allele
• Individuals only have to receive one dominant allele from one
parent to have the disease.
• Very rare
• Appears later in life – Most often these individuals pass on the
disease to their children before they know they have it.
• Ex/ Huntington’s Disease
Simple Dominant
• If a normal homozygous recessive woman and a man who was
heterozygous for Huntington’s had 4 children, what would be
the probability of their children’s genotypes?
3. Sex-linked
• Trait/disease is carried on the X or Y chromosome
• Most of these genes are carried on the X chromosome so they
mostly affect males
• Ex/ Male pattern baldness, Fur color in cats, Hemophilia (a
blood clotting disorder)
Sex-linked
• In cats, the trait for orange and black fur is carried on the X
chromosome. Calico cats are black and orange and can only
be female. Explain why male cats can not be calico.
Sex-linked
• Draw a punnett square for a heterozygous female carrier and a
normal male. What is the genotypic ratio of their children?
• XH X – Mother
• X Y – Father
4. Incomplete Dominance
• A heterozygous individual has an “intermediate” phenotype.
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Ex/
RR – red flower
WW – white flower
RW – pink flower
Incomplete Dominance
• In beta fish, green (GG) and steel blue (BB) and incompletely
dominant traits. A royal blue fish (GB) is an intermediate
color. If two royal blue fish mated, what would be the ratio of
their offspring?
5. Codominant
• A heterozygous individual expresses both traits.
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Ex/
BB – Black Feathers
WW – White Feathers
BW – Black and White Feathers
• If you crossed a purebred black with a purebred white, what
would be the genotypes and phenotypes of their offspring?
Codominant
• RR – Red Flower
• WW – White Flower
• RW – Red and White Flower
• If you crossed two heterozygous flowers, what would be the
ratio of their offspring?
Codominant
• Blood type is a codominant trait. A type blood and B type
blood are equally dominant. O type blood is recessive. If
someone receives an A allele and a B allele, they will express
both phenotypes and have type AB blood. A child has O type
blood. His mother has A type blood and his father has B type
blood. Could those be his biological parents? Explain.
RH Factors in Blood Type
Who can give blood to who?
6. Multiple Alleles
• When there are 3 or more alleles that exist in a population for
a particular gene.
• Ex/ Rabbit Fur color
• In a population of rabbits, there is an allele for solid color fur,
chinchilla colored fur (speckled), Himalayan fur (certain parts
of the body), and albino fur.
• Each individual rabbit only receives 2 alleles, but there are 4
possible alleles in the entire gene pool of rabbits.
Multiple Alleles
7. Polygenic Traits
• A trait that is controlled by 2 or more genes.
• Ex/ Eye color
Polygenic Traits
• Skin Color
8. Epistasis
• An epistatic gene interferes with the expression of other
genes.
• Causes albinism