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25 Cards in this Set
- Front
- Back
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What is the prevalence of single gene disorders?
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2% (20/1,000)
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How many 1st trimester spontaneous abortions are due to chromosome disorders?
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50%
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What is the prevalence of chromosome disorders?
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7%
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What are multifactorial disorders due to?
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predisposing factors (ie. genotype) + environmental factors
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Define alleles
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Alternate forms of a gene in a population
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What is a constitutional mutation/
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If one was born with the mutation (from birth)
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What is polymorphism?
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When alleles are so common that they're found in more than 1% of chromosomes int he general population
(versus rare variants) |
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What is a locus?
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position on a chromosome where a particular gene is located
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What is cytogenetics?
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Study of chromosomes, their structure, their inheritance
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What is combinatorial control?
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Combinations of a few gene regulatory proteins can generate many diff cell types
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What is karyotyping?
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Staining of metaphase chromosome with dye (metaphase spread)
- generates specific banding patterns for each chromosome |
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Can you do a karyotype of interphase cells?
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No, only metaphase/pro-metaphase b/c chromosomes must be condensed
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What are the 3 possible locations of the centromere?
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acrocentric - near the end of the chromosome
metacentric - approx. in the middle of the chromosome submetacentric - close to the middle, but asymmetrically positioned so that the two arms are of unequal length |
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What are the names of the two kinds of arms on the chromosome?
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p arm - petite/short arm
q arm - long arm |
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What is the process of generating a specific banding protein (karyotype)?
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- Peripheral blood leukocytes (stimulated with a mitogen)
- A lectin aglutinates RBCs, so they can be removed by centrifugation - Inoculated into nutrient medium - Colchicine is added (inhibits spindle formation) - hypotonic solution - so cells swell - drop cells on slide. PM and nuclear membrane break, chromosomes are released and attach to slides by electrostatic forces |
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What is G banding?
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- trypsin/heat removes protein from DNA-Giemsa staining
- light/dark bands - dark bands = AT rich (repeated DNA) - banding pattern represents location of repetitive DNA - |
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When would you want high resolution or prometaphase banding of chromosomes in a more uncondensed state?
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to detect more subtle chromosome abnormalities
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What is Q banding?
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quinacrine mustard-binds
fluorescent signal bright bands = AT rich (same as dark bands in Giesma - G banding) |
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What is R banding?
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Reverse of G bands
- Heat treatment - Acridine orange |
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What is C banding?
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centromeric region and other regions containing heterochromatin in the chromosome
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How much of the human genome encodes genes?
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Less than 10%
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1/2 of the total linear length of the genome is single copy. what does single copy mean?
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Represented only once or a few times per haploid genome
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How much repetition is in DNA?
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Long stretches of unique DNA are rare.
Lots of repetition (several classes of repetitive DNA) |
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Give 3 examples of repetitive DNA
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Short, clustered repeat sequences (Satellite DNA)
repetitive, dispersed DNA (LINES, Alu sequences - SINE family) |
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How much of the genome is clustered repeat sequences?
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10-15% (interspersed between coding sequences)
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