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38 Cards in this Set
- Front
- Back
Dominant Gene - def'n |
A gene seen in organisms with the homozygous and heterozygous genotypes |
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Recessive Gene - def'n |
A gene seen in organisms with the homozygous genotype only |
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Haplosuffient - def'n |
One copy of a gene is sufficient to produce the wild-type phenotype in the heterozygous genotype |
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Haploinsuffient - def'n |
A single copy of a gene is not sufficient to produce the wild-type phenotype in the heterozygous genotype |
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Loss of Function Mutation |
Results in a significant decrease or in the complete loss of the functional activity of a gene product |
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Gain of Function Mutation |
Identification of alleles that have acquired a new function of have their expression altered in a way that gives them substantially more activity that the wild-type allele |
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Null/Amorphic Mutation - def'n |
A loss-of-function mutation that results in a complete loss of gene function in comparison to the wild-type gene product. The mutant alleles produce no functional gene product and are often lethal in a homozygous genotype |
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Leaky/Hypomorphic Mutation |
A mutation resulting in partial loss of gene function . Often recessive and lethal. |
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Hypermorphic Mutation |
Mutation that produces more gene activity per allele than the wild-type.
Usually Dominant |
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Neomorphic Mutation |
Gain-of-function mutation resulting in novel gene activity not found in the wild-type |
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Incomplete (Partial) Dominance |
The phenotype of the heterozygote is intermediate between the phenotypes of the homozygous organisms |
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Codominance |
The equal and detectable expression of both alleles in heterozygotes |
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Allelic Series - def'n |
An order of dominance among alleles, based on the activity of each allele's protein product. |
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Allelic Series - e.g. |
Coat color determination in rabbits, where C = wild-type ch = Chinchilla h = Himalayan c = Albino Allelic Series: C > ch > h > c |
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Lethal Allele |
Single-gene mutation so detrimental that it causes death early in life or in gestation |
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Sex-limited trait |
When both sexes carry a gene for a trait, but it is expressed in only one sex |
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Sex-influenced Traits |
Traits in which the phenotype corresponding to a particular genotype differs depending on the sex of the organism |
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Delayed age of onset |
Abnormalities manifest after the affected organism has had an opportunity to reproduce and transmit the mutation to the next generation |
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Complete Penetrance |
Phenotype for a trait is always produced when the corresponding genotype is present |
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Incomplete Penetrance |
A particular genotype does not always produce the corresponding phenotype |
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Variable Expressivity |
One genotype produces phenotypes that vary in degree or form of expression |
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Gene-Environment Interaction |
The result of the influence of environmental factors on the expression of genes and on the phenotypes of organisms |
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Pleiotropy |
A single gene mutation that affects multiple and seemingly unconnected properties of an organism |
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Gene Interaction |
The collaboration of multiple genes in the production of a single phenotypic character or a group of related characters |
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Prototroph |
Wild-type |
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Auxotroph |
Mutant, i.e. organism with mutations that prevents its growth on a minimal medium |
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Epistatis |
Gene interactions in which an allele of one gene modifies or prevents the expression of alleles at another gene |
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Hallmark of a Epistatic Interaction in a Dihybrid Cross |
A modification of the 9:3:3:1 ratio due to the combining of two or more genotype classes into a single phenotypic class |
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Dominant Epistatis - ratio |
12:3:1 |
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Recessive Epistasis - ratio
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9:3:4 |
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Complementation Group |
Mutations of a single gene - i.e. many alleles - that do not complement one another |
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Recessive Epistatis |
Phenotype produced by the interaction of two genes that control a trait in which alleles of one gene mask or reduce the expression of alleles of a second gene |
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Nonpenetrant |
An organism with a genotype corresponding to a mutant phenotype that instead displays the wild-type phenotype |
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Genetic Heterogeneity |
Same phenotype produced by mutation of any one of two or more different genes |
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Temperature-sensitive Allele |
A mutation evident only at or above a certain temperature due to an abnormality of the protein product that affects its stability |
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Genetic Complementation |
1. The observation of a wild-type phenotype in an organism or cell containing two different mutations
2. The cross of two pure-breeding mutants that yields progeny that are exclusively wild-type |
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Dominant Epistatis |
Interaction of two genes that control a trait in which a dominant allele of one gene masks or reduces the expression of alleles of a second gene |
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Penetrant |
Expression of the phenotype corresponding to a particular genotype |