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35 Cards in this Set
- Front
- Back
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What are cohesions?
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proteins that hold the sister chromatids together so they look like one unit
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tripoloidy
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3 sets of chromosomes. 69:xxx. Rarely live born. caused by dispermy
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tetraploidy
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4 sets of chromosomes. 92xxxx. Mitotic nondisjunction in first zygotic division. rarely live born
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What does nondisjuction in Meiosis 1 cause?
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trisomy with both parent chromosomes
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What does nondisjunction in meiosis II cause?
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trisomy with only one set of parent genes
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What is an unbalanced reaarrangement?
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phenotypically abnormal and mentally retarded
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What is a balanced rearrangement?
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carriers are phenotypically normal, but at risk for producing a child with an unbalanced chromosome complement
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What is an inversion? (inv)
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Results from two breaks within same chromosome. The broken piece does a 180 turn.
2 ways, paracentric and pericentric. |
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What is paracentric Inversion?
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Breaks are in the same arm of the chromosome. Centromere is not involved. Rare, shape of chromosome does not change.
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What is pericentric inversion?
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involves region including centromere. One break in short, one in long, changes shape. unbalanced gametes. duplication or deletion.
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What is a chromosomal deletion? (d)
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The loss of chromosomal segments. Can be interstitial (2 breaks) or terminal (1 break)
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What does hemizygous mean?
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A carrier of a deletion (one normal homolog and one deleted homolog)
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What is chromosomal insertion?
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Removal and insertion of a segment to a different site on the same or different chromosome. Can be direct or inverted.
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What is chromosomal translocation?
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Exchange of chromosomal material between two or more non-homologous chromosomes.
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What is a ring chromosome?
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Formed between two ends of a chromosome when telomeres are lost. Rings are very unstable and may be lost during cell division
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What is chromosomal duplication?
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additional copy of a chromosome segment. Partial trisomy. Direct or inverted.
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How does chromosomal duplication occur?
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Originates by unequal crossing over or by abnormal segregation during meiosis. May disrupt important genes. Can lead to abnormal phenotypes
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What is an isochromosome?
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When you lose one arm entirely. In the end there will be 2 q arms and 2 p arms.
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What happens if you lose the p arm in an acrocentric chromosome?
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If it occurs in an acrocentric p arm, it will not severely affect the individual. the P arm contains rRNA, which is present in 5 acrocentric chromosomes and abundant
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What is a robertsonian translocation?
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The fusion of the centromere region of two acrocentric chromosomes. (13,14,15,21,22)
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What chromosomes go to the nucleus?
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acrocentric chromosomes
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Why is Robertsonian translocation important in the clinic?
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The carriers are phenotypically normal. Are at risk for miscarriages and have abnormal live born children.
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What deletion causes Angelman Syndrome?
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The MATERNAL deletion on the 15q chromosome
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What deletion causes Pradder WIlli syndrome?
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The PATERNAL deletion on the 15q chromosome.
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Pradder WIlli and Angelman system are examples of what?
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genomic imprinting
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What is chromosomal duplication?
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additional copy of a chromosome segment. Partial trisomy. Direct or inverted.
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How does chromosomal duplication occur?
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Originates by uneual crossing over or by abnormal segregation during meiosis. May disrupt important genes. Can lead to abnormal phenotypes
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What is an isochromosome?
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When you lose one arm entirely. In the end there will be 2 q arms and 2 p arms.
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What happens if you lose the p arm in an acrocentric chromosome?
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If it occurs in an acrocentric p arm, it will not severely affect the individual. the P arm contains rRNA, which is present in 5 acrocentric chromosomes and abundant
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What is a robertsonian translocation?
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The fusion of the centromere region of two acrocentric chromosomes. (13,14,15,21,22)
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What chromosomes go to the nuclues?
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acrocentric chromosomes
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Why is Robertsonian translocation important in the clinic?
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The carriers are phenotypically normal. Are at risk for miscarriages and have abnormal live born children.
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What deletion causes Angelman Syndrome?
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The MATERNAL deletion on the 15q chromosome
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What deletion causes Pradder WIlli syndrome?
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The PATERNAL deletion on the 15q chromosome.
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Pradder WIlli and Angelman system are examples of what?
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genomic imprinting
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