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13 Cards in this Set
- Front
- Back
What is a transcription factor?
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a protein that binds to specific DNA sequences, thereby controlling the flow (or transcription) of genetic information from DNA to mRNA.
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What is added at the 5' end and the 3' of the primary transcript?
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a 'cap' and Poly (A), repsectively
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Non-disjuntion in meiosis 1 leads to what type of gametes and what type of cells
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nullisomic gametes producing monosomic cells (45 ch'somes)
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Non-disjuntion in meiosis 2 leads to what type of gametes and what type of cells
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Disomic gametes producing trisomic cells (47 ch'somes)
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All cases of monosomy are lethal except one - what is it? How does it manifest?
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Turner syndrome (45 ch'somes, X0).
Failure to develop secondary sexual characteristics. Gonads degenerate to connective tissue at birth |
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What is another name for trisomy 21?
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Down syndrome
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Name 3 trisomies in the sex chromosome and what problems they cause?
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Triple-X sydrome (XXX). Some mild retardation, 25% inferile.
Jacob's syndrome (XYY). Usually asymptomatic (possible motor coordination problems). Kinefelter's syndrom (XXY). Mild learning difficulties and infertility. |
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Some triplet repeat diseases exhibit anticipation. What is meant by this?
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Repeats can increase in successive generations. Can lead to progressively earlier onset in each generation.
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What causes Huntington's disease?
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A triplet repeat expansion (>36) of CAG within the huntington gene. When expressed this mutant gene leads to the damage of nerve cells
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What causes Fragile X syndrome?
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the expansion of the CGG trinucleotide repeat affecting the Fragile X mental retardation 1 (FMR1) gene on the X chromosome, resulting in a failure to express the fragile X mental retardation protein (FMRP), which is required for normal neural development
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State 3 molecular explanations for dominant diseases mutations
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Haploinsufficiency.
Dominant negative effect Gain of Functional effect |
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What is incomplete penetrance (Genetics)
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Dominant disorders are not apparent in all individuals.
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What is heterozygote advantage in the case of sickle cell anaemia
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Homozygotes suffer from sickle cell anaemia but heterozygotes don't and have additional resistance to malaria
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