Chromosomal Chromosomal Inheritance and Inheritance and

Human Sex Human Sex DeterminationDetermination

Chromosomes!Chromosomes!

Is this what Mendel would Is this what Mendel would expect?expect?

Is this Is this what what

Mendel Mendel would would

expect?expect?

If a color blind man has a child with If a color blind man has a child with a “wild-type” woman, what are the a “wild-type” woman, what are the chances that this chances that this daughterdaughter of theirs of theirs will be colorblind?will be colorblind?

What are the chances that their What are the chances that their sonson will be colorblind?will be colorblind?

Can females be colorblind? What Can females be colorblind? What would the genotype of the parents would the genotype of the parents have to be?have to be?

Practice Question: Practice Question: Chromosomal InheritanceChromosomal Inheritance

Human Sex Human Sex DeterminationDetermination

Textbook Story:Textbook Story:

XX = FemaleXX = Female

XY = MaleXY = Male

With a few With a few exceptions….exceptions….

OccasionallOccasionally, y,

chromosomchromosomes fail to es fail to

sort sort correctly correctly resulting resulting

in in aneuploidy aneuploidy (unusual (unusual

numbers of numbers of chromosomchromosom

es)es)

XXY = Klinefelter Syndrome- phenotypically male with normal intelligence, sterile

XO = Turner syndrome- phenotypically female, sterile, usually normal intelligence

XYY = no general traits (tall)

XXX = healthy, “normal”

Aneuploidy can also occur with Sex Chromosomes

The The SRY SRY GeneGene

Hormonal Signaling is Hormonal Signaling is ComplexComplex

Hormone Production is Hormone Production is ComplexComplex