GENETICS II Patterns of Inheritance n n n

Patterns of Inheritance n n n Autosomal Dominant Autosomal Recessive X-linked Dominant X-linked Recessive

What is a Pedigree Chart? n Pedigree Charts A pedigree chart shows the relationships

PEDIGREE CHART A shaded circle or square A circle indicates that a person represents

Pedigree for Albinism, an Autosomal Recessive Trait

What is a karyotype? n n A karyotype is a photograph of chromosomes grouped

SEX DETERMINATION X X = FEMALE XY = MALE

Sex Determination Female XX x ½X Male XY ½X ½ X ¼ XX ½

n Males and females are born in a roughly 50 : 50 ratio because

SEX-LINKED TRAITS Color blindness X+-Linked DOMINANT XC-Linked RECESSIVE

Color blindness: Alleles: X+ = normal vision, Xc = color blind (X+ is dominant)

Pedigree for Colorblindness, an X-linked Recessive Trait

HEMOPHILIA • • This is a sex-linked trait that is carried on the X

X-linked Genes Hemophilic Male X h. Y Non-hemophilic Female (father is hemophilic) x X

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GENETICS II

Patterns of Inheritance n n n Autosomal Dominant Autosomal Recessive X-linked Dominant X-linked Recessive Y-Linked Inheritance

What is a Pedigree Chart? n Pedigree Charts A pedigree chart shows the relationships within a family. n Helpful to parents understanding the probability of their child having particular genotypes or inherited disorders. n Colorblindness n Hemophilia n Albinism n

PEDIGREE CHART A shaded circle or square A circle indicates that a person represents expresses the trait. a female. A horizontal line connecting a male and a female represents a marriage. A square represents a male. A vertical line and a bracket connect the parents to their children. A circle or square that is not shaded indicates that a person does not express the trait.

Albinism

Pedigree for Albinism, an Autosomal Recessive Trait

What is a karyotype? n n A karyotype is a photograph of chromosomes grouped in pairs These chromosomes are from a typical human body cell.

HUMAN KARYOTYPE

SEX DETERMINATION X X = FEMALE XY = MALE

FEMALE CHROMOSOMES

MALE CHROMOSOMES X Y

Sex Determination Female XX x ½X Male XY ½X ½ X ¼ XX ½ Y ¼ XY Phenotypic Ratio of Offspring ½ Female + ½ Male 50%: 50%

n Males and females are born in a roughly 50 : 50 ratio because of the way in which sex chromosomes segregate during meiosis.

SEX-LINKED TRAITS

SEX-LINKED TRAITS Color blindness X+-Linked DOMINANT XC-Linked RECESSIVE

Color blindness: Alleles: X+ = normal vision, Xc = color blind (X+ is dominant) phenotypes normal color blind carrier* female genotypes X+ X+ Xc Xc X+ Xc * carrier - carries but does not show the trait male genotypes X+ Y Xc Y

Pedigree for Colorblindness, an X-linked Recessive Trait

What number do you see?

HEMOPHILIA • • This is a sex-linked trait that is carried on the X chromosome The blood does not clot XH = Normal Xh = Hemophilic

X-linked Genes Hemophilic Male X h. Y Non-hemophilic Female (father is hemophilic) x X HX h XH Xh Xh X HX h X h Y X HY X h. Y Phenotypic Ratio of Offspring 25% hemophilic males : 25% non-hemophilic males 25% hemophilic females : 25% non-hemophilic females

Royal Families of Europe Pedigree