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48 Cards in this Set
- Front
- Back
What do chromosomes consist of? 2
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histones (proteins)
DNA |
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What is chromosome morphology based on?
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length and position of centromere
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Why can't chromosome morphology be studied in non-dividing cells?
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chromosomes remain elongated and entangled
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What designates the short arm of chromosome?
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p
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What designates the long arm of chromosome?
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q
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Metacentric?
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centromere is located in the center, both arms are equal length
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Submetacentric?
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centromere is located close to the center but is slightly displaced towards one end
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Acrocentric?
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centromere is a or almost near the end of the chromosome
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Telocentric?
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the centromere is at or almost near the end of chromosome
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Acentric?
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chromosomes lack a centromere
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Satellites?
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secondary constrictions
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How are chromosomes arranged in a karotype?
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by size, centromere position, banding pattern
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What cells can karotypes be generated from?
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white blood cells
cancer cells connective tissue |
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Why are white blood cells good for generating karotypes?
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they dont divide easily and are therefore induced to divide
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Why are cancer cells good for generating karotypes?
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actively dividing cells, easy to make karotype
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Why is connective tissue good for generating karotypes?
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easy to culture
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What does karotypes help recognize? 3
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abnormality in chromosome structure, abnormality in chromosome numbers, chromosome ploidy
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Banding?
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treatment of chromosomes by reageants that generate a characteristic of horizontal bands
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What are the different types of banding? 5
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G-banding, R-banding, Q-banding, T-banding, FISH banding
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G-banding: dark and light regions?
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-dark regions are heterochromatic (late replicating and AT rich)
-light regions are euchromatic, early replicating and GC rich |
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R-banding: light and dark regions?
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reverse of G-banding
light regions are heterochromatic dark regions are euchromatic |
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Q banding: staining?
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quinacrine is used to obtain fluorescent staining
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T-banding: what does it visualize?
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telomeres
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What does FISH detect and what is it useful for?
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detection and analysis of abberrant karotype and complex chromosomal arrangements
-useful in diagnosis of certain types of cancers |
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Chromosome deletion: what is it, what does it cause, how can it be discovered?
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-part of chromosome is lost
-causes severe congential anomalies and marekedly retarded mental and physical development -may be discovered prenatally if karotype is performed for other reasons |
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Chromosome Duplication: what is it, what does it result from?
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part of chromosome is dupilicated, 3 copies instead of 2
-results from unequal crossing over (recombination) that occurs between misaligned homologous chromosomes during meiosis |
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What is chromosome inversion?
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a chromosome is clipped out, turned upside down and reinserted back into the chromosome
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Balanced inversion?
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genetic makeup remains the same, even though order of alleles has changed
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Unbalanced Inversion: what is it, what does it cause?
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genes have been deleted or duplicated
-causes problems and birth defects |
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Paracentric Inversion?
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inverted area does not include the centromere, inversion in within the arm
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Pericentric Inversion?
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inverted area included the centromere
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Chromosome Translocation?
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rearrangement between nonhomologous chromosomes
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What are types of abnormalities in chromosome number? 3
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ploidy, euploidy, aneuploidy
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Ploidy?
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number of homologous sets of chromosomes
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Euploidy?
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each homologous pair is present as an exact integer multiple of the haploid number
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Aneuploidy?
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less or more than the normal diploid number chromosomes
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Types of Aneuploidy?
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Monosomy
Nullisomy Trisomy |
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Monosomy?
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loss of one chromosome from a chromosome pair, the entire chromosome or partial can be missing
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What defects result from Monosomy?
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Turners syndrome, Cri du chat
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Turners syndrome chromsomes?
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women have one X instead of 2
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Nullisomy?
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one entire chromosome pair is missing
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Trisomy?
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three chromosomes instead of 2
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Trisomy defects? 6
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down syndrome
edwards syndrome patau syndrome triple x syndrome klinefelter syndrome XYY syndrome |
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Down syndrome chromsome defect?
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trisomy 21
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Edwards syndrome chromosome defect?
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trisomy 18
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Patau syndrome chromosome defect?
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trisomy 13
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Klinefelter syndrome sex chromosome defect?
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XXY
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How does trisomy arise?
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due to non-disjunction during meiosis 1 or 2
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