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GeneticsExam3-B
Question | Answer |
---|---|
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. |