Sex and mitochondrial inheritance.txt

  1. What is the Lyon Hypothesis?
    At least one X chromosome is inactivated to allow "dosage compensation"
  2. 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
  3. What is the specific inactive area on an X chromosome called?
    Barr Body
  4. How do you calculate Barr bodies?
    Number of X chromosomes - 1
  5. What % of genes on the X chromosome escape inactivation?
  6. What two genes are still expressed in inactivated X chromosomes?
    • XIST gene (XIC center)
    • Pseudoautosomal regions
  7. 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
  8. What sex is more likely to express an X-linked recessive disease?
    Males, because they are hemizygous (XY)
  9. 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
  10. 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
  11. What is a sex-influenced trait?
    Autosomal trait expressed more frequently in different sex
  12. What are three examples of a sex-influenced trait?
    • 1) male baldness
    • 2) Gout
    • 3) Hereditary hemochromatosis
  13. What is a sex-limited trait?
    only one sex affected
  14. How many genes are in mitochondrial DNA?
  15. What are the three features of mitochondria?
    • 1) Replicative segregation, random
    • 2) Homoplasmy/Heteroplasmy
    • 3) Strictly maternal inheritance (egg has more mt)
  16. 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
  17. What are three characteristics of mt inheritance?
    • 1) only females transmit
    • 2) non-mendelian inheritance
  18. 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
Card Set
Sex and mitochondrial inheritance.txt
Sex linked and mitochondrial inheritance