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18 Cards in this Set
- Front
- Back
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The first antibiotic to be discovered in 30 years was |
teixobactin |
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What are three situations in which inheritance of characters by a single gene may divate from Mendlian patters? |
1. when alleles are not completely recessive or dominant 2. When a gene has two or more alleles 3. when a gene produces multiple phenotypes |
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List five possible allele relationships for a single gene |
1. Complete dominance of one allele 2. Incomplete dominance of either allele - red flower, white flower make pink flower 3. Codominance - 4. Multiple alleles - blood type 5. Pleiotropy - sickle-cell disease |
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Pleiotropy |
genes that have multiple phenotypic effets -Ex: pleiotropic alleles are responsible for the multiple symptoms of hereditary diseases such as sickle cell anemia |
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Are dominant alleles more common? |
No, polydactyly (extra fingers or toes) -1 in 500 canadians - |
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Epistasis |
The phenotypic expression of a gene at one locus alters that of a gene at a second locus Ex: Gene 1 determines black or brown, gene 2 determines pigment or no pigment. -if homozygous for recessive Gene 2, it doesn't matter what gene one is carrying, the coat will not have pigment and will be yellow as a result |
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Norm of reaction |
A genotype generally is not associated with a rigidly defined phenotype, but rather with a range of phenotypic possibilities due to environmental influences -epigenetics ex: person's blood count or pressure varies with the level of physical activity |
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Why are human's poor experimental subjects for genetics? |
-very few offspring -generation time is too long -breeding experiments are unacceptable |
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True or False: Mendelian genetics is the foundation of human genetics. |
True |
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What is the most common lethal genetic disease in Canada and how many ppl does it effect? |
Cystic fibrosis, 1/3600 |
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Cystic Fibroisis |
-recessive -normal allele for this gene codes for a membrane protein that functions in the transport of choloride ions between certain cells and the extracellular fluid -chloride transport channels are defective or absent for children that inherit 2 recessive alleles for cystic fib -leads to high concentration of chloride, disrups sodium transport, -results in mucus build up |
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What is an example of a genetic disorder with evolutionary implications? |
sickle cell disease, 1/400 african americans |
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Sickle cell, homo/hetero, what does it result in? |
Sickle-cell hemoglobin molecules aggregate into long rods that defom the red cells into a sickle shape -sickled cells may clump and clog small blood vessels -homozygous -although, the presence of one sickle-cell allel can affect the phenotype |
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Why are lethal dominant alleles so rare? |
Infected individuals usually die before they can reproduce and pass allele to future generations |
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What is an example of disease caused by a lethal dominant allele? Explain |
Huntington's disease -trinucleotide repeat disorder -leads to defective protein -causes deterioration of the nervous system -irreversible and fatal |
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How has the alleles for Huntington's disease been able to be passed on unlike other lethal dominant alleles? |
B/c symptoms of Huntington's disease do not begin appearing until an advanced age (35-45 yrs) |
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Multifactoral Disease |
People that are susceptible to diseases because of a genetic component and a significant environment component |
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What are four tests conducted during prenatal screening? |
-down syndrome -Tay-Sachs -Spina bifida -Trisomy 18 |
