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GeneticsExam3-B

QuestionAnswer
Mutation? a change in a gene's DNA.
Germline mutation? a mutation during meiosis and is passed on through the resulting gametes.
Somatic mutation? a mutation during mitosis and is only found in one person.
Normal hemoglobin? has 2 alpha and 2 beta chains; the 6th amino acid of the beta chain is glutamine.
Sickle cell hemoglobin? the beta chains are messed up; the 6th amino acid of the beta chain is valine.
Collagen? protein found in connective tissue; formed from 3 polypeptides.
Early onset Alzheimer's? a mutation in the presenilin 1 gene allows beta amyloid plaques to form earlier than usual.
Mutagens? things that create mutations; x-rays, UV light, ethydium bromide.
Ames test? bacterial test to see if a chemical is a mutagen.
T or F. The more mutant bacteria there are, the more mutagenic the chemical is. TRUE
Spontaneous mutation? a new mutation in either the sperm or egg; neither parent has the disease or carries a recessive allele.
Mutational hot spot? a repeated section of DNA that is easily mutated.
Palidromes? mutational hot spots.
Point mutations? only one base changed; substitutions.
Transition? Purine (A or G) replaces a purine or a pyrimidine (T or C) replaces a pyrimidine.
Transversion? purine and pyrimidine swap.
Missense mutation? one codon is changed; the resulting protein has the wrong amino acid and doesn't work; sickle cell hemoglobin.
Nonsense mutation? one codon is changed into a stop codon; only part of the protein is made; the short protein doesn't work; BRCA1, missing clotting factor X1.
Neutral mutation? one codon is changed; the resulting protein has the wrong amino acid, but the protein does work; hemoglobin Machida. **(you can also change the codon to a codon that codes for the same amino acid).
Frame shift mutations? shifts the codon reading frame so that everything behind it is messed up.
Insertion? adds extra base; Huntington's disease adds about 100 CAGs.
Deletion? messing a base; Duchenne muscular dystrophy is missing large portions of the gene.
Tandem duplication? 2 copies of a gene next to each other.
Expanding repeats? as the repeat expands, it causes more problems; myotonic muscular dystrophy, fragile X syndrome.
Excision repair? mismatched DNA is found later, the mistakes can be cut out and replaced by correct bases.
Nucleotide excision repair? removes up to 30 bases at a time; usually replaces damage from chemical carcinogens and UV light.
Base excision repair? repairs 1-5 bases at a time; usually replaces damage from free radicals.
Mismatch repair? DNA polymerase checks for a mismatch and fixes it while the DNA strand is being replicated; usually fixes microsatellite lengths.
Xeroderma pigmentosum? missing nucleotide excision repair mechanisms; prone to skin cancer.
Inherited colon cancer? missing mismatch repair mechanism; prone to colon cancer.
Chromosomes? condensed DNA that is visible during cell division.
How many pairs of chromosomes do humans have? 23
Cytogenetics? links chromosome variations to specific traits.
Karyotype? a picture of chromosomes, usually sorted from biggest to smallest.
How to make a karyotype? 1. Grow cells in a tissue culture flask. 2. Add Colchicine that stops mitosis at metaphase. 3. Add Giemsa dye on the cells to highlight the dark + light bands. 4. Drop the cells on a slide from 12 inches high. 5. Look at cells under powerful microscope.
Heterochromatin? dark bands; mostly genes; mostly repetitive DNA.
Euchromatin? light bands; mostly genes; but it is not one gene per light band.
Telomeres? region at the end of chromosomes; TTAGGG repeat; gets shorter with each round of replication; short telomeres are associated with aging.
Centromere? spot where sister chromatids join together; where spindle fibers attach; 171 base repeat.
Telocentric? centromere on the very end of the chromosome.
Metacentric? centromere is in the very middle of the chromosome.
Acrocentric? centromere is close to the end of the chromosome.
Submetacentric? centromere is not quite in the middle, but close; divides the chromosome into 2 arms of unequal length.
P arm? short arm of the chromosome.
Q arm? longer arm of the chromosome.
Sonogram? ultrasound to check on baby; can see gross abnormalities, but not chromosomal problems; done 13-14 weeks after conception.
Amniocentesis? take cells from fluid surrounding baby, inside amnion; grow cells to make more; do karyotyping or PCR testing for genetic diseases; done 14-16 weeks after conception.
Polymerase Chain Reaction (PCR)? a technique for quickly amplifying DNA.
Chorionic villus sampling? a small piece of the chorion is removed and tested for genetic diseases; done 8-10 weeks after conception.
Preimplantation Genetic Diagnosis (PGD)? testing embryos for genetic diseases like sickle cell anemia, cystic fibrosis, and Tay Sachs; done 4-6 days after conception.
Fluorescence in situ Hybridization (FISH)? uses probes complimentary to specific DNA sequences; if the chromosomes have the DNA sequence, the probe lights up and it is easy to see.
Euploid? have a normal number of chromosomes.
Aneuploid? having an abnormal number of chromosomes.
Triploid? 3 copies of every chromosome.
Polyploid? having more than 2 copies of every chromosome.
Nondisjuncture? when the chromosomes don't separate in meiosis.
Trisomy? an extra copy of one chromosome.
Down's Syndrome? 3 copies of chromosome #21; trisomy 21; symptoms include mental retardation, heart problems, kidney defects, poor muscle tone; often from nondisjuncture in older women's eggs.
Trisomy 18? Edward's syndrome; symptoms include severe physical and mental disabilities, heart defects, often the defects are so bad the fetus dies; often from nondisjuncture in women's eggs.
Trisomy 13? Patau syndrome; symptoms include cleft palate and other facial problems, and digestive problems, often the defects are so bad the fetus dies.
XO (Turner Syndrome)? female, thick neck, few secondary sexual characteristics, many have hearing defects, usually sterile; normal intelligence.
Monosomic? missing one copy of one chromosome.
Metafemale? XXX; normal female
Klinefelter's male? XXY; effeminate, often sterile; mildly slow learners.
XYY? Jacob's syndrome; tall, fertile.
OY? dead.
Deletion? missing pieces of a chromosome.
Cri du Chat? cry of the cat syndrome; missing part of the short arm of chromosome 5; symptoms include a high pitched cry, mental retardation, delayed development and short lifespan.
Duplication? a region where genes are repeated.
Translocation? relocation of parts of nonhomologous chromosomes.
T or F? Down's syndrome can also be caused by a translocation of a piece of chromosome #21 with a piece of chromosome #14? TRUE.
Robertsonian translocation? 2 different acrocentric chromosomes lose their short arms and fuse the long arms into 1 long chromosome.
Reciprical translocation? 2 different chromosomes exchange equal parts.
Inversions? change the order of genes.
Paracentric Inversion? does not include the centromere in the inversion.
Pericentric Inversion? includes the centromere in the inversion.
Uniparental disomy? when you have nondisjuncture of the same chromosome from each parent; one gamete lacks the chromosome, the other gamete has 2 copies; very rare.
Created by: mamcdonald on 2010-03-13



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