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NBCHBCH10.2Johnson
10.2 How do Alleles Interact
Question | Answer |
---|---|
A genetic locus with a wild type allele that is present less than 99 % of the time is said to be ____________. | polymorphic |
What does wild type mean? | this allele is the one present in most individuals in nature and gives rise to an expected trait or phenotype. |
What is the opposite of wild type alleles? | mutant alleles |
Dominance is complete when an individual is ______________. | heterozygous |
When is it siad that a gene is governed by incomplete dominace? | when heterozygtes show a phenotype intermediate between those of the two homozygotes ( neither of 2 alleles are dominant) |
What is serum? | blood from which cells have been removed |
Explain codominance. | when 2 alleles at a locus produce 2 different phenotypes that both appear in heterozygotes. |
What are the four different blood types? | A, AB, O, B |
Can a single allele affect more than just one phenotype? | yes; because sometimes an allele has more than one distinguishable phenotypic effect |
When an allele has more than one distinguishable phenotypic effect it is _________. | pleiotropic |
What is an example of pleiotropy? | Siamese cats; the allele that determines their coloration pattern also determinesthe crossed eye trait. |
What is an example of incomplete dominance? | If rr white sapdragons are crossed with RR red snapdragons and the flower is pink |
What is an example of codominance? | the ABO blood groups system in humans beause in AB both the A and B antigens show up in the genotype |
How is incomplete dominance different from the blending theory? | blending theory states if the pink f1 generation was crossed with white then the f2 would be lighter pink. in fact howver half the offspring is white and the other half is the same shade pinnk as f1 |
What is an antigen? | proteins on the surface of "non-self" cells |