NUR 332 Exam 2 - Module 3 Genetics[ch 2,3,4 1 Chromosomes alterations and associated disorders[3 a Homologous 22 of 23 pairs are identical in

NUR 332 Exam 2 - Module 3 Genetics[ch 2,3,4 1 Chromosomes...

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Module 3 - Genetics [ch. 2,3,4] 1. Chromosomes alterations and associated disorders [3] a. Homologous - 22 of 23 pairs are identical in appearance - sex chromosomes = 2 homologus cells X chromosomes in female and nonhomolous pair, X and Y for males - 46 chromosomes in 23 pairs ( Normal) b. Euploid [eu = good/true] cells - abnormal multiple of the normal chromosomes [normal = 46 chromosomes] ex : An embryo that contains a normal number of chromosomes is a ' euploid ' embryo. i. Polyploid cell - when a euploid cell has more than the diploid number [ex: Triploidy ( ex: when a zygote that has 3 copies of each chromosomes rather than the normal 2) / tetraploidy (a condition in which euploid cells have 92 chromosomes c. Aneuploid cell - does not have multiple of 23 chromosomes i. Trisomy - a condition where the cells has 3 copies of 1 chromosomes ii. Partial Trisomy- in which only an extra portion of a chromosome is present in each iii. Monosomy - condition where the cell has only 1 copy of a given chromosome iv. Nondisjunction - an error where homologous chromosomes fail to separate during meiosis and mitosis ---- aneuploidy is usually a result v. Principle = loss of chromosome material has more serious consequences than duplication of chromosome material Zygote with no X chromosome will not survive d. Autosomal aneuploidy [disorders] i. Down syndrome - trisomy of chromosome 21 1. Systemic disorders : congenital heart disease, low immune system, increased leukemia, symptoms of Alzheimer's disease table 2-1 page 46 2. Causative factors : 97% by nondisjunction, 3% translocation ii. Turner syndrome - 45 X, monosomy of x chromosomes [only females] - Sex linked 1. Systemic disorders : coarctation [narrow] aorta, edema of feet in
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newborns, sterile [can’t reproduce], gonadal streaks rather than ovaries sometimes leading to cancer 2. Causative factors : 75% from mother caused by error in father iii. Klinefelter syndrome - 47 XXY, XXY condition [males] -sex linked 1. Systemic disorders : sparse body hair, sterile, small tessticles, long limbs, breast development 2. Causative factors : 50% of nondisjunction of X in mother; XXY and XXXY karyotypes causing physical and mental impairment iv. Cri du chat syndrome - “cry of the cat” described as the cry of the child, low birth weight, intellectual disability, microcephaly [small head], and heart defects; short arm of chromosome 5 1. Deletions - broken chromosome and lost DNA Ex the zygote has one chromosome with the normal complement of genes and one with some missing 2. Duplications - less serious physical effect but causes mental retardation 3. Inversions - 2 breaks of a chromosome, reinserted, but in inverted order [ex: ABCDEFG → ABEDCFG] although it can cause position effect resulting in physical defects leading to duplication and deletions 4. Translocation- interchange of genetic material between nonhomologous chromosomes - Reciprocal translocation occurs when breaks take place in 2 different chromosomes and material is exchange. The carrier is usually normal but his or her offspring can have duplications or deletions.
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