Inheritance of Traits Probability Carriers Autosomal Sex-linked Pedigrees Complex patterns of heredity Incomplete dominance Codominance Multiple Alleles Practice

Inheritance of Traits Probability- the likelihood that a specific event will occur When you flip a coin, there is a 50/50 chance it will land tails side up If there are 4 kids in a family, probability says 2 will be girls and the other 2 will be boys

Inheritance of Traits Carrier- an individual who is heterozygous for an inherited disorder but does not show symptoms. Ex. Linda is a carrier for albinism. Genotype-(Aa) Phenotype- not albino Even though she does not display the symptoms, she can still pass on albinism to her children.

Inheritance of Traits Autosomal- when a gene is autosomal, it will appear in both sexes Sex-linked- when a gene is sex-linked, it is found only on the X or Y chromosomes so the effects are only seen in males. Remember, males are (Xy) and females are (XX) Examples- colorblindness, hemophilia, Cystic Fibrosis and Sickle Cell Anemia

Inheritance of Traits Sex-linked Punnett Square for colorblindness: X Key: XX- female Xy- male Xby- colorblind male XXb- female carrier XbXb- colorblind female Xb y What are the offspring?

Inheritance of Traits Sex-linked Punnett Square for colorblindness: Xb Key: XX- female Xy- male Xby- colorblind male XXb- female carrier XbXb- colorblind female X y What are the offspring?

Inheritance of Traits Sex-linked Punnett Square for colorblindness: Xb Key: XX- female Xy- male Xby- colorblind male XXb- female carrier XbXb- colorblind female Xb y What are the offspring?

Pedigrees Pedigree- a family history that shows how a trait is inherited over several generations Useful to track the carriers of genetic disorders in families Can be used for both autosomal and sex-linked disorders

Pedigrees Pedigree for albinism: Key: Female Male (P1) Female carrier Female with albinism Male with albinism Married with children (P1) (F1) (F2) *The order of children is from left to right

Pedigrees Pedigree for albinism: C D E F G H I J K Which individuals are heterozygous for albinism? Which are homozygous for albinism? Which individuals have albinism? Which generations have an individual with albinism?

Complex Patterns of Heredity Polygenic inheritance- when several genes influence a characteristic Incomplete dominance Codominance Multiple alleles

Complex Patterns of Heredity Incomplete dominance- when an individual displays an intermediate/middle phenotype of the parents Ex. A red (RR) snapdragon flower is crossed with a white (rr) one and their offspring are pink (Rr)

Complex Patterns of Heredity Codominance- when two dominant alleles are expressed at the same time Ex. Blood types- AB blood A A B AB AB AB AB B

Complex Patterns of Heredity Codominance Ex. Roan horses (have both red and white hair)

Complex Patterns of Heredity Multiple alleles- genes with 3 or more possible alleles Ex. Blood types- A, B, O (AB- codominant)

Practice Blood Type If a man is homozygous for type B blood, and has a child with a homozygous woman with type A blood, what are the possible blood types of the child? Phenotype Genotype Type A Type B Type AB Type O AA or AO BB or BO AB OO

Practice Blood type A man is heterozygous for type A blood and has a child with a woman that has AB blood. What are the possible blood types of the child? Phenotype Genotype Type A Type B Type AB Type O AA or AO BB or BO AB OO

Practice Incomplete dominance Assume: Red= RR White = rr or WW or R’R’ Pink= Rr or RW or RR’ You cross a red flower with a white flower: What happens?