genes and heredity part 2

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genes and heredity part 2
2012-07-24 16:55:32
genes heredity part

genes and heredity part 2
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  1. Abnormal chromosome diseases
    • [1] Caused by error in the number or structure of chromosomes
    • [2] Chromosomal abnormalities usually result from an error occurring when an egg or sperm cell develop
    • [3] Some chromosomal abnormalities result in miscarriage or stillbirth
    •  [4] Many children with a chromosomal abnormality have mental and/or physical defects
  2. Down syndrome
    • {1} A genetic condition in which a person has 47 chromosomes instead of the usual 46
    • {2} Occurs when there is an extra copy 0f chromosome 21, called trisomy 21
    • {3} Incidence is 1 in 800, higher in children born to mothers over age 35
    • {4} Life expectancy is relatively short due to complications such as congenital heart disease
    • {5} Increased susceptibility to respiratory tract infections
    • {6} High incidence of leukemia
    • {7} Mental retardation ranges from mild to sever
    • {8} Physical development is often slower than normal
    • {9} Short stature, never reach average adult height
    • {10} Children may have delayed mental and social development
  3. Down syndrome Treatment
    • a} No specific treatment
    • {b} Major surgeries to immediately after birth to treat
    • <1> Intestinal blockage
    • <2> Atrial and/or ventricular septal defects
    • <3> Behavioral training
    • <4> Special education
    • <5> Speech, physical, and occupational therapies
  4. Cri Du Chat (French for cry of the cat) syndrome
    • {1} Also known as 5p- (5p minus) syndrome
    • {2} Caused by a missing piece of chromosome 5 that may play a role in control of cell growth
  5. Sex anomalies
    • Chromosome mutations may occur due to exposure to mutagens such as radiation 
    • [a] Chromosome breakage is a result of one type of mutation
    • [b] Broken chromosome fragment may be deleted, duplicated, inverted, or translocated to a non-homologous chromosome
    • [c] Mutations occurring during meiosis cause cells to have either too many or too few chromosomes
  6. Turner syndrome
    • {a} One X chromosome is missing (genotype
    • is XO)
    • {b} Persons appear female, but
    • <1> Ovaries do not develop
    • <2> No ovulation or menstruation
    • <3> Person is sterile
    • <4> Mammary nipples widely spaced apart
    • <5> Breasts do not develop
    • <6> Develop congenital heart disease- coarctation of the aorta
  7. Klinfelter syndrome
    {a} Extra X chromosome (genotype is XXY)

    • {b} Person appears male, but
    • <1> Testes do not develop
    • <2> No sperm production
    • <3> Person is sterile
    • <4> Breast enlargement and female distribution of hair occurs
    • <5> Little facial hair
    • <6> Appearance of immature adult
    • <7> Person is mentally impaired
  8. Intersex or disorders of sex development
    •  hermaphroditism
    • Pseudohermaphroditism
  9. hermaphroditism
    • {a} A group of conditions where there is a discrepancy between external (testes) and internal (ovaries) genitalia
    • {b} At birth an unambiguous assignment of male or female cannot be made
    • {c} Newborn may exhibit both male and female sexual characteristics and organs
    • {d} The number of true hermaphrodites is small
  10. Pseudohermaphroditism
    • {a} A state in which an individual has internal reproductive organs of one sex while exhibiting physical characteristics of the opposite sex
    • {b} May have either testes or ovaries that are usually nonfunctional
    • {c} Sex chromosome differs from anatomic sex and is referred to sex reversal
    • {d} In some instances pseudohermaphroditism may be due to excessive sex hormone production from the adrenal cortex
  11. Genetic
    • [1] Goal is to obtain complete, detailed family history or pedigree from prospective parents
    • [2] Pedigree is used to determine pattern of inheritance of a genetic disease within a family
    • [3] Diagnosis of genetic diseases
  12. Two
    diagnostic techniques
    • Amniocentesis
    • Chorionic villi
  13. Amniocentesis
    • Amniotic fluid drawn after the 14 week of pregnancy examining for
    • <1> Recovery of fetal cells for analyzing fetal chromosomes
    • <2> Examining for biochemical abnormalities in amniotic fluid
    • <3> Test results obtained within 2 weeks
    • <4> ~200 genetic diseases can be detected before birth
  14. Chorionic villi
    • {a} Projections of the membrane
    • surrounding the embryo in early pregnancy

    • <1> Involves removing cells from the villi through the cervix
    • <2> Samples collected between 8 and 10 weeks of pregnancy to allow time for exploring various options
    • <3> Chromosomes can be analyzed immediately
    • <4> Results if gender and chromosomal information obtained sooner in the pregnancy
  15. Gene therapy for genetic diseases
    • {1} Involves identification, manipulation, and transference of genetic segments into a host to replace defective genes
    • {2} Goal of gene therapy
    • {a} Replace a mutated gene that causes disease with a healthy copy of the gene
    • {b} Inactivate, or “knocking out”, a mutated gene that is dysfunctional
    •  {c} Introduce a new gene into the body to help fight a disease
  16. Congenital diseases
    • [1] Disease appearing at birth or shortly afterwards
    • [2] Not caused by genetic or chromosomal abnormalities
    • [3] Arise from some failure during embryonic development or first 2 months of pregnancy
    • [4] Cannot be transmitted to offspring
    • [5] Exposure to various factors during first trimester can produce serious defects
  17. Exposure
    to various factors during first trimester can produce serious defects
    • [a] Maternal infections
    • [b] Inadequate oxygenation
    • [c] Drugs
    • [d] Malnutrition
    • [e] Radiation
  18. Age-related diseases
    • 1] Appearance of disease at birth
    • [2] Appearance of disease a few months
    • after birth
    • [3] Appearance of disease in third or
    • fourth decade of life
  19. [3] Appearance of disease in third or fourth decade of life
    • [a] Hemochromatosis
    • [b] Huntington’s chorea
    • [c] Parkinson’s disease
  20. Appearance of disease a few months after birth
    • [a] Tay-Sachs disease
    • [b] Cystic fibrosis
  21. Age-related diseases 
    • [a] Phenylcktonuria (PKU)
    • [b] Galactosemia