Genetics- test 2

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bbeckers88
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115322
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Genetics- test 2
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2011-11-07 22:23:16
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genetics- test 2
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  1. autosomal dominant inheritance
    a disease/trait that is caused by a dominant allele on an autosomal chromosome
  2. what combinations show affecteds in autosomal dominant?
    • AA
    • Aa
  3. is AA a common combination for autosomal dominant disorders?
    • no, its usually lethal
    • Aa is more common
  4. what is the pedigree appearance for autosomal dominant disorders
    • affected persons have affected parents
    • vertical look
    • if affecteds mate with normal, offspring are affected 50%
  5. can autosomal dominant disorders skip generations?
    yes, due to reduced penetrance
  6. huntingtons disease
    • autosomal dominant
    • neurodegenerative disorder
  7. signs of huntingtons
    progressive involutary twitching, personality changes, demential, and death
  8. what causes huntingtons
    mutant gene undergoes a trinucleotide repeat/expansion
  9. what is the average age of onset for huntingtons?
    40
  10. osteogenesis imprefecta
    • autosomal dominant type 1 collagen disorder
    • most common is type 1
  11. s/sx of osteogenesis imprefecta
    brittle bone disease, short stature, malformed bones, loose joints, blue sclera, opalescent teeth, hearing diorders
  12. neurogibromatosis type 1
    • aka: vonrecklinghausen disease
    • autosomal dominant
    • tumor growth along nerves
    • neurofibromas
    • high new mutation rate
  13. achondroplasia
    • autosomal dominant bone growth disorder
    • non-proportional dwarfism
    • 75-90% are new mutations
  14. marfans syndrome
    autosomal dominant CT disorder
  15. s/sx of marfans syndrome
    tall persons with dys-proportionally long limbs, arachnodactyly, subluxation of eye lenses, cardiovascular disease
  16. polycystic kidney disease
    • autosomal dominant progressive kidney disease
    • multiple cysts in kidney
    • ADPKD- nonmotile renal tubule cilia
  17. congenital:
    • present at birth
    • could be genetic or not
  18. heredity
    inherited...genetic for sure
  19. familial
    • runs in familys
    • could be genetic or not
  20. genetic
    caused by genes...genetic (duh!)
  21. autosomal recessive inheritance
    • classical mode of inheritance
    • a disease/trait is caused by a recessive eallele
  22. we are all varriers of how many harmful recessive alleles??
    • 5-8 (part of our genetic load)
    • this is because the typical transmission of recessive alleles is silent (Aa)
  23. what combinations are considered affecteds with autosomal recessive inheritance?
    aa
  24. pedigree appearance of autosomal recessive disorder
    • no prior family history
    • horizontal look
    • recurrent risk in sibship= 25%
    • affected mating with a normal= normal
    • often consanguinity if abnormality is rare
  25. is the number of of carriers of autosomal recessive genes common?
    • yes!!
    • genetic load (5-8)
  26. PKU
    • autosomal recessive disorder of amino acid metabolism
    • accumulation of phenylalanine
    • uncommon
  27. s/sx of PKU
    severe mental retardation, hypo-pigmentation, unusual odor
  28. albinism
    • autosomal recessive disorder of amino acid metabolism
    • deficiency of melanin
    • uncommon
  29. Tay-Sachs disease
    • autosomal recessive disorder of lipid metabolism
    • uncommon/rare (variable depending on the population- common in ashkinazi jews)
  30. cystic fibrosis
    • aka: mucoviscidosis
    • autosomal recessive disorder of chloride transport (fails to enter cells)
    • exocrine gland secretion is difficult
    • not uncommon
    • respiratory infections
  31. s/sx of cystic fibrosis
    very salty sweat, thick respiratory mucus, bacterial growth, blockage of biliary tract, poor digestion, pancreatic insufficiency
  32. autosomal co-dominant inheritance
    heterozygotes have different phenotype than either homozygote, intermediate inheritance
  33. what are the combinations for autosomal co-dominant inheritance
    • AA= unaffected
    • Aa= semi-affected, phenotype ranges from almost normal to mild form of disease
    • aa= affected
  34. familial hypercholesterolemia
    • autosomal co-dominant
    • high servum cholesterol (LDLs) because of LDL receptor disease
    • severe form is very rare
    • mild form is 1 in 500 (heterozygotes)
  35. describe the mild form of familial hypercholesterolemia
    • total serum cholesterol 250-500 range
    • elevated risk of MI by age 60 (85% in males, 50% in females)
  36. sickle cell anemia
    • autosomal co-dominant
    • abnormal hemoglobin causing anemia and caso-occlusive crises
    • homozygous recessive have classic disease
    • heterozygotes are basically normal (have "sickle cell trait")
    • much more common in african/mediteranian descent
  37. why is it thought that the sickle cell trait (Aa) is more common in african and mediteranian descents
    • 1 in 12 africans have it
    • evolutionary selection against malarial infection (heterozygote superiority)
  38. normal female karyotype
    46, XX (homogametic)
  39. normal male karyotype
    46, XY (heterogametic, hemizygous)
  40. what is the important gene on the y chromosome?
    • sex determining region Y (SRY)
    • female is the default setting
  41. does having a Y chromosome garuntee a male?
    no, could be translated to a different gene
  42. are the bulk of genes for sexual differences on autosomes or sex chromosomes?
    autosomes! they are just activated by which sex chromosome you have
  43. barr bodies
    only 1 x chromosome remains active in a cell, the second X (in a female) forms a chromatin "lump" called a barr body
  44. sex chromosome defects
    • all are aneuplodies
    • the greater the # of sex chromosomes, the greater the change for serious phenotypic consequences
    • as a group, are relatively common
  45. Klinefelter's syndrome
    • aka: testicular hylanization
    • 47, XXY aneuploidy
    • MALES, with female characteristics
    • non uncommon
  46. what are some characteristics on kleinfelters syndrome?
    • sterility
    • tall/lanky
    • gynecomastia
  47. turners syndrome
    • aka: gonadal dysgenesis
    • 45, XO aneuploidy
    • FEMALES with male characteristics
    • somewhat uncommon (causes ~10% of miscarriages)
  48. characteristics of turner's syndrome
    • steril
    • broad/sheild chest
    • webbed neck
  49. tripple X syndrome
    47, XXX
  50. XYY syndrome...
    ... 47, XYY (duh)
  51. hermaphroditism
    • intersex
    • ambiguous genitalia
  52. holandric genes
    • genes that are not essential for survival
    • almost all the genes on the Y chromosome
  53. defective testicular development usually due to:
    deletion or mutation of SRY
  54. x-linked genes are found where:
    on the x-chromosome
  55. x-linked recessive inheritance
    • all of your X chromosomes must have the gene to be affected, soooooo
    • females must be Xa, Xa
    • males must be Xa, Y
  56. pedigree characteristics of x-linked recessive disorders
    • mainly males affected
    • an affected male cant pass the trait on to his sons
  57. hemophilia A
    • x-linked recessive
    • missing blood clotting factor 8
    • results in bleeding
    • very uncommon
  58. common colorblindness
    • x-linked recessive
    • very common (so common you also see it in females!!)
    • usually red-green confusion
  59. duschenne MD
    • x linked recessive
    • progressive muscle weakness/wasting
    • young males
    • uncommon
  60. fragile X syndrome
    • x liked recessive
    • mental retardation (#1 inheritable cause!!!!)
    • triplicate expansion, variable expansion causes variable expression
    • not uncommon
  61. male pattern baldness
    • x linked recessive
    • pattern of hair loss in males
    • very common in males
  62. sex related inheritance
    some genes are expressed differently depending upon the sex of the individual
  63. sex influenced inheritance
    variable expression of an autosomal gene depending on the individuals sex
  64. hemochromatosis
    • autosomal recessive
    • high serum iron content
    • treatment is periodic phlebotamies
    • seen mainly in males becuase females get natural phlebotamies monthly...yea us
  65. s/sx of hemochromatosis
    malaise, liver cirrhosis, bronzing of the skin, cardiomegally
  66. sex limited inheritance
    expression of a genetic trait that is limited to one sex or another (ex: horns on deer)

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