unit5 - Unit 5: Genetic Testing Fall 2008 Genetic Testing...

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1 Unit 5: Genetic Testing Fall 2008 Genetic Testing Methods include analysis of: Chromosome structure DNA sequences Protein products, by products Different Genetic Tests are used to analyze the different products or by-products of the gene expression pathway (DNA to RNA to protein).
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2 Types of Genetic Diseases Chromosome disorders gain or loss of a whole chromosome rearrangement or translocation (part of chromosome) e.g., cause syndromes - Down, Kleinfelter, Angelman Monogenic diseases inheriting a single gene causes the disease gene can be dominant, recessive, or in between e.g., cystic fibrosis, Huntington’s, hemophilia, sickle cell disease, Duchenne muscular dystrophy Polygenic diseases inheritance is not clear cut (many genes involved) also called “multi-factorial” diseases e.g., autism, asthma, heart disease, cancers, manic depression, diabetes, many more, SIDs
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3 Some DNA Genetic Tests Use DNA Probes Genetic Tests analyze DNA, RNA, or chromosomes (DNA packaged with proteins); look for mutations or chromosome abnormalities associated with genetic diseases. Tests monitor the activity of mutant proteins (mutant genes) by detecting the products of mutant enzyme; reveals the identity of the genetic disease. A DNA “probe” is used to see if a person’s genome contains a specific gene; the DNA “probe” will base pair ONLY with the specific gene in the genome that has DNA sequence complementary to the probe.
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4 DNA probes make specific base-pairing interactions Target DNA in chromosome (2) Single-stranded probe DNA carrying a “visible tag” (fluorescent) DNA probes make very specific base-pairing interactions with the target DNA in the chromosome. Only a DNA probe with a sequence complementary to the target DNA will successfully base-pair to the target DNA.
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5 “Painted” human chromosomes make a spectral karyotype. Chromosomes from a human male (left) arranged into a spectral karyotype (right). Human chromosomes are ‘painted’ with different DNA-specific fluorescent dyes (DNA probes) that allow us to identify each chromosome by color (spectral karyotype).
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6 Chromosome rearrangements visible in spectral karyotype Spectral chromosome image: white arrows indicate the chromosome translocations involving chromosome 19 with 5 and chromosome 11 with 15 (inset).
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7 Karyotype of normal human chromosomes Banding patterns on human chromosomes. (left) Mitotic chromosomes are stained to see banding patterns on condensed chromosome arms. Typical karyotype display of 46 chromosomes (46, X, Y) from a human male. (right) 46 , XY
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8 Reciprocal chromosome translocation – No genes lost Reciprocal translocation of DNA between chromosomes 4 and 20 occurs; NO LOSS of essential genes.
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9 Chromosome deletions, duplications and rearrangements Chromosome
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This note was uploaded on 09/09/2011 for the course BIOCHEM 100 taught by Professor Dr.mollyfitzgerald during the Fall '09 term at UMass (Amherst).

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unit5 - Unit 5: Genetic Testing Fall 2008 Genetic Testing...

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