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20 Cards in this Set
- Front
- Back
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Chromosome aberrations
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Health depends on inheriting correct amount of genetic material.
Large scale changes visible w/ light microscope and stains Extra genetic material=less damaging than losing material |
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Cytokensis
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matching of phenotypes to dectable chromosomal abnormalities
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Chromosome structure
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=made of proteins and DNA
regions: telomeres, origins of replication, centromeres |
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Telomeres
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=tips of chromosomes
gets smaller w/ each division |
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Centromeres
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=constricted portion of a chromosome
Metacentric: divides chrom. equally Submetacentric: creates 1 long arm (q) and 1 short arm (p) Acrocentric: creates 1 very short arm |
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Artificial chromosomes
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uses in gene therapy, vehicle for inserting healthy versions of genes
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Karyotype
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Metaphase chromosomes squashed on slide and stained w/ DNA dye.
Need actively dividing cell and at metaphase stop the cell from doing anything else |
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Karyotype uses
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Clinical: diagnose genetic conditions
Public Health: toxins that cause chrom. aberrations Evolutionary studies: to indicate evolutionary relatedness b/w species |
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Visualizing chromosomes
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amniocentisis
chorionic villus sampling fetal cell sorting |
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Amniocentisis
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Remove fetal cells from uterus 14-16 weeks
Cells cultured for 1 week and 20 cells are karyotyped Causes miscarriage 1/350 cases Often in older women |
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Chorionic Villus Sampling
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Remove fetal cells from chorionic villi 10-12 week
Earlier detection of potential problems (but less precise) Greater risk of miscarriage 1/125 |
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Fetal Cell Sorting
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separates fetal cells from mother's blood stream
Safe but experimental |
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Polyploidy
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extra SETS of chromosomes
triploid=1 extra copy of every chromosome-> too much genetic info, very disruptive (miscarriage) |
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Aneuploidy
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one missing chromosome or one extra chromosome
trisomy= extra monosomy=missing (usually fetal) |
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Autosomal Aneuploidy
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Trisomy 21: down's syndrome (mental retardation, short stature, sparse hair, poor reflexes)
Trisomy 18: Edward syndrome (heart defects, displaced liver, growth retardation, sever mental retardation) clenched fists |
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Sex Chromosome Aneuploidy syndroms
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Turner: XO females (delays sexual devt)
Klinefelter: XXY males. (delays sexual devt, causes long limbs) XYY: causes tallness and acne.falsely linked w/ violent beh |
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Deletions and Duplications
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=extra or missing copies of genes
May be minimal/ no effect on phenotype |
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Inversions
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=segment of a chromosome becomes reversed
Large or no effect on phenotype, depends on chromosome |
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Translocations
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=nonhomologous chromosomes exchange segments
Robertsonian: causes loss of genetic info. Reciprocal: rearrages genetic info (not same as crossing over b/c nonhomologous chromosomes) |
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Isochromosomes
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chromatids divide along wrong plane
Results in chromosomes w/ identical arms |
