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Patho Exam 2: Module 3-5-Genetics (Ch. 2-4): 16 Questions oChromosomes: what’s normal, what causes abnormality, syndromesNormal: Euploid cells:multiple normal number of chromosomesHaploid cells:normal gametes, 1 member of each chromosome pair, 23 chromosomes, formed from diploid cellsDiploid cells:normal somatic cells (46 chromosomes and 23 pairs) father and mother donate 1 chromosome per pairAbnormalities: leading cause of mental retardation and miscarriage Polyploidy:euploid cell has some multiple of the normal number of chromosomes Triploidy:three copies of each chromosome (lethal)Tetraploidy:four copies of each chromosome (lethal)Aneuploid:are somatic cells that DO NOT have a multiple of 23 chromosomes oTrisomy: 1 chromosome is present in 3 copies in somatic cellsDown Syndrome: a trisomy of chromosome 21, caused by chromosome aberration Occurs in births where women are 35 years or olderoPartial Trisomy: 1 part of a chromosome is present in 3 copies oMonosomy: 1 chromosome is present in 1 copy in somatic cellsCause MORE severe physical defects = a loss of chromosome material has a detrimental impact than duplications. Sex Chromosomes: o47 XXX karyotypesoTurner Syndrome (45 X)oKlinefelter Syndrome (47 XXY)o47 XYY karyotypeAbnormalities of Sex Chromosomes: deletions, duplications, inversions, translocationsoSyndromes/Diseases: Know signs and symptoms and causesof abnormality (Page 46, 2-1)Klinefelter’sCharacteristics:small testes, some development of breast, sparse body hair, longlimbs, moderate mental impairment, voice high pitchedCauses: presence of 2 or more X chromosomes with 1 Y chromosome, nondisjunction of X chromosome in mother, increase maternal age, mental impairment with each X added, mosaicism
Turner Syndrome Characteristics:short stature, female genitalia, webbed neck, shield-like chest with underdeveloped breasts and widely spaced nipples, imperfect ovaries, coarctation of aorta, edema of feet in newborns, sterile, gonadal streaks rather than ovaries Cause:Monosomy of sex chromosome, inherit X from mother, meiotic error in father, combinations of 45, X calls with XX or XYCri du chatCharacteristics:“cry of the cat”, low birth weight, severe intellectual disability, microcephaly (small head), heart defectsCauses: deletion of part of the short arm of chromosome 5 Down SyndromeCharacteristics: IQ 20-70, low nasal bridge, epicanthal folds, protruding tongue, low set ears, poor muscle tone (hypotonia), short stature, CHD, respiratory tract infections, increase susceptibility of leukemia, decrease survival rateCauses: trisomy of chromosome 21, nondisjunction during formation of one parent’s gametes, translocation, mosaics Huntington’sCharacteristics:autosomal dominant disease, neurological, progressive dementia, uncontrollable limb movement, delayed age of onset (symptoms not seen until 40), unaware as children, muscle problems, slow eye movement, impaired gait, difficulty with speech and swallowing Causes: trinucleotide repeat mutation, 1 copy of the defective gene