Download Sex-Linked Inheritance Student Notes • Sex linked inheritance

Sex-Linked Inheritance Student Notes
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Sex linked inheritance varies the Mendel number of __________________by
having males a 50/50 percent chance of inheriting the characteristic on the X
chromosome only.
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Remember, __________________ have XX and ____________________ are XY.
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The ____________ carries little genetic information, mainly those that contribute to ________________
characteristics.
(About _____________ genes total.)
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The _________ carries a lot more genetic information. (About ______________ genes total.)
What is Sex-Linked Inheritance?
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Genes for certain traits are on the X chromosome only…
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Since ________________ only receive one X chromosome then they are ____________________ to
inherit these types of disorders.
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Who gives men the X Chromosome?
____________________________________
_____________________ are somewhat protected since they receive two X chromosomes and are less
likely to inherit these types of disorders.
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What do you think happens when they get only one defective copy of an X chromosome?
________________________________________________________________________
Patterns of Sex-Linked Inheritance
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The vast majority of affected individuals are _______________.
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Affected ___________ never pass the disease to their _________
because there is no male-to-male transmission of the _______
chromosome.
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Affected __________ pass the defective X chromosome to all of their
________________, who are described as _____________.
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This means they carry the disease-causing allele but generally
show no disease symptoms since a functional copy of the gene
is present on the other chromosome.
______________ carriers pass the defective X chromosome to…
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half their ________ (who are affected by the disease)
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half their ___________ (who are therefore also carriers).
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Other children inherit the _________ copy of the chromosome.
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The overall pattern of the disease is therefore characterized by the transmission of the disease from affected
males to male grandchildren through carrier daughters, a pattern sometimes described as a
_________________________________.
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Affected females, with two deficient X chromosomes, are the rare products of a marriage between an
_____________________________________________________________________________________
Solving Sex-Linked Problems
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You determine which trait (or disorder) is
_____________________ or ___________________________.
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Set up a punnett square using XX for females and XY for males.
–
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Assign ________________________ for _______ only!
Solve as usual, keeping in mind that the Y chromosome has
____________________________!
YOUR TURN!
Hemophilia is a sex-linked trait where XH gives normal blood clotting and is dominant to the hemophilia allele Xh.
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Identify the genotypes of…
1) a woman with normal blood clotting whose father had hemophilia
Genotype: ________________________________________
2) a normal man whose father had hemophilia.
Genotype: ________________________________________
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What is the probability that a mating between these two individuals will
produce a child, regardless of sex, that has hemophilia?
Child with Hemophilia: _____________________________________________________________