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34 Cards in this Set
- Front
- Back
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Down syndrome |
trisomy 21, autosomal, flat face, extra folds in eyelids, sparse hair, thick tongue, poor reflexes, floppy, varied intelligence. heart, kidney, hearing, vision often impaired suppressed immune system, digestive problems |
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Turner syndrome |
XO - female with only 1 X chromosome, most die in utero. short, webbing on back of neck, incomplete sex development (hormone deficient) |
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Klinefelter syndrome |
XXY male with an extra X, incomplete sex development, large hands/feet, some breast tissue, infertile. some go undiagnosed. |
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Most common extra autosomes? |
13,18,21 |
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Jacobs syndrome |
XYY, extra Y. most phenotypically normal. sometimes tall, acne, minor speech and reading problems. |
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Polyploidy |
3 copies of each chromosome. results from 2 sperm fertilizing one egg or haploid sperm fertilizes diploid egg. Error in cell division in which all chromatids fail toseparate at anaphase. Multiplefertilizations |
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Aneuploidy |
An unusual number of chromosomes. Usually spontaneously aborted unless sex chromosomes. Often results from nondisjunction. |
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Is nondisjunction worse in Meiosis I or II? |
I is worse. |
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What are the most common autosomal trisomies? |
13,18,21. they are typically more severe than the sex trisomies. |
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Trisomy 18 |
Edward syndrome, few survive birth, major abnormalities: heart, liver, growth, oddly clenched fists, low ears, etc. Nondisjunction in meiosis II of the oocyte probably cause. |
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Trisome 13 |
Patau syndrome, few survive birth, severe eye problems: fusion of the eyes or a small/missing eye. also abnormalities: heart, kidneys, brain face limbs |
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Triplo-X aneuploidy |
XXX, slightly lowered intelligence, often tall, irregular menstrual periods |
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What is the mitochondrial aneuploidy? |
Trick question! there is no mitochondrial aneuploidy. |
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What are the different types of mutations? |
Deletions: missing material Duplication: repeated gene Robertsonian translocation: nonhomologous chromosomes break at centromere and long arms fuse (short arms often lost) Reciprocal translocation: nonhomologous chromosomes exchange portions of their arms Inversion:Breakage and reunion with wrong orientation. |
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What is the difference between paracentric and pericentric inversions? |
Para: no centromere Peri: includes centromere |
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dicentric or acentric fragments. |
Crossover between paracentricinversion and normal homologue |
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Isochromosome |
Division of centromeres on wrong plane |
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Ring chromosome |
Loss of telomeres and fusion of ends. |
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Somatic vs. Germline mutations |
Somatic: can't be transmitted to offspring (responsible for certain cancers) Germline: Possibly will be transmitted to offspring. |
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spontaneous mutation |
de novo/new mutations. Not caused by known mutagen. Errors in DNA replication. rate differs, everyone has them. Bact/viruses: can lead to resistance to treatment/drugs. |
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Areas prone to mutations |
Short repetitive sequences (pairing of repeats may interfere w/ replication of repair enzymes) Palindromes: often associated w/ insertions/deletions Duplications of larger regions mispairing during meiosis. |
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Induced mutations |
by chemicals or radiation. Mutagens (chemicals causing mutations) or carcinogens (chemicals causing cancer) |
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Ames test |
testing the mutagenicity of a substance (using salmonella and mutant gene for histidine) |
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Types of mutations: |
Point mutation: change of a single nucleotide (transition purine to purine or transversion purine to pyrimidine) Missense mutation: point mutation changing codon (but not to a stop codon) Nonsense mutation: changing a codon to a stop codon Splice site mutations: affects where introns would be removed. Insertion/deletions mutations: causes a frameshift Expanding mutation: insertion of a triplet repeat |
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pseudognes |
a DNA sequence reminiscent of a gene, but not translated (may or may not be transcribed) |
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Silent mutation/synonymous codons |
silent mutations: don't alter aa sequence synonymous codons: 2 different codons that code for the same aa |
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conditional mutations |
only produce phenotype under particular conditions/environments. |
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DNA repair |
nucleotide excision repair: up to 30 bases (UVB/carcinogen repair) Base excision repair: 1-5 bases (oxidative damage) Mismatch repair: incorrect base excised and replaced. |
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Sickle cell anemia |
Point mutation changing glutamic acid to valine. |
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Elhers-Danlos syndrome |
Collagen mutation: missense, deletion or disruption of splicing. produces stretchy, easily scarred skin and lax joints. |
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Alzheimers disease |
mutations in presenilin1 cause early onset. |
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common diseases caused by mutations. |
Cystic fibrosis, duchenne muscular dystrophy, familial hypercholesterolemia, hemophilia A, huntington disease, marfan syndrome, neurofibromatosis |
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Myotonic dystrophy |
expanding triplet repeat disease |
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xeroderma pigmentosa |
deficient excision repair |
