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Sex and mitochondrial inheritance.txt
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What is the
Lyon Hypothesi
s?
At least one X chromosome is inactivated to allow "dosage compensation"
What are the four characteristics of the Lyon Hypothesis?
1) X inactivation is
Random
2) X inactivation is
Early
3) X inactivation is
Permanent
4) X inactivation is
Incomplete
What is the specific inactive area on an X chromosome called?
Barr Body
How do you calculate Barr bodies?
Number of X chromosomes - 1
What % of genes on the X chromosome escape inactivation?
15%
What two genes are still expressed in inactivated X chromosomes?
XIST gene (XIC center)
Pseudoautosomal regions
What effect does a
pseudoautosomal gene
have on a male and femal?
Male = inherited part of maternal X chromosome
Femal = inherited part of Paternal X chromosome through
synapsis
**not sex linked
What sex is more likely to express an X-linked recessive disease?
Males, because they are hemizygous (XY)
What are the 3 guidelines for determining X-linked recessive genes?
Males affected more than females
No Father-son transmission
skip generations due to female carriers
What are the 3 guidelines for determining X-linked dominant genes?
1) males transmit to daughters only
2) Females more highly affected (2x's), but expression less severe than male heterozygotes
3) vertical transmission
4) no father-to-son transmission
What is a
sex-influenced trait
?
Autosomal trait expressed more frequently in different sex
What are three examples of a
sex-influenced trait
?
1) male baldness
2) Gout
3) Hereditary hemochromatosis
What is a
sex-limited trait
?
only one sex affected
How many genes are in mitochondrial DNA?
37
What are the three features of mitochondria?
1) Replicative segregation, random
2) Homoplasmy/Heteroplasmy
3) Strictly maternal inheritance (egg has more mt)
What is Heteroplasmy/Homoplasmy?
Heteroplasmy
: When one infected mtDNA and one normal mtDNA passed on
Homoplasmy:
When either two infected or two normal mtDNA are passed on
What are three characteristics of mt inheritance?
1) only females transmit
2) non-mendelian inheritance
What two areas are most affected by mt diseases and why?
Muscular system and CNS
**happens because Mt are present in sites of high ATP/ETC
Author
kepling
ID
54454
Card Set
Sex and mitochondrial inheritance.txt
Description
Sex linked and mitochondrial inheritance
Updated
2010-12-09T02:31:03Z
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