Traits can be traced through a family tree Pedigree Practice In humans albinism is a recessive trait The disorder causes a lack of pigment in the skin and hairs making an albino person appear very pale with white hair and pale blue eyes This disorder also occurs in animals The pedigrees bel ID: 535853
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Slide1
Pedigree
Traits can be traced through a family tree.Slide2
Pedigree Practice
In humans, albinism is a recessive trait. The disorder causes a lack of pigment in the skin and hairs, making an albino person appear very pale with white hair and pale blue eyes. This disorder also occurs in animals. The pedigrees below trace the inheritance of the allele that causes albinism.
1. Given the following genotypes, describe the phenotypes (normal or albino)
AA=
Aa=
a
a=Slide3
Fill in the Pedigree with the genotypes of the family members
How many males are there in this family?
How many children are there?
How many in the family are Albino?
How many in the family are carriers
?Slide4
Fill in the Pedigree with the genotypes of the family members
How many males are there in this family?
How many grandchildren are there?
How many are Albino?Slide5
But what determines whether we are male or female?
Vocabulary
Autosomal Chromosomes
Any chromosome that is not a sex chromosome
Sex Chromosomes Chromosomes that determine the sex of an organismSex-Linked Traits Alleles/genes found on sex chromosomesSlide6
But what determines whether we are male or female?
Female
= XX
Male =
XYIn most organisms the X chromosome is larger and holds many more genes that code for many traitsVocabulary
X-linked trait- A trait found on the X chromosome
Y-linked trait- A trait found on the Y chromosomeSlide7
Sex-Linked traits
Genes found on sex chromosomes are written as superscripts above the chromosome it is linked to.
Colorblindness is an X-linked Recessive Trait.
Write the genotypes for the following phenotypes.
a. Homozygous non-colorblind female = _______b. Carrier female = ______
c. Colorblind female = _____d. Non-colorblind male = _____
e. Colorblind male= _____Show the cross between person b. and person d.Slide8
Hemophilia is x-linked recessiveSlide9Slide10
Expression of X-linked Traits
In autosomal chromosomes, or any chromosome that is not a sex chromosome there are two copies of an allele
Males only have one copy of an X-linked allele because they only have one X chromosome
I
f a male has a recessive trait on the X chromosome of a it will be shown in the phenotypeX chromosome inactivation: Where one of the X chromosomes is “turned off” in different parts of a cell resulting in a patchwork of cellsSlide11Slide12
X-InactivationSlide13
Sex-linked Pedigree- Hemophilia