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33 Cards in this Set
- Front
- Back
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Population Genetics |
Studies genetic variation in a population & how variation changes over time; different populations have different genetic compositions |
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Gene Pool |
All of the alleles for every gene in a population |
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Microevolution |
Changes in allele frequencies that occur in a population from one generation to the next |
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Natural selection |
Selects for traits that enhance survival & reproductive success |
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Fitness |
The relative likelihood that a particular genotype will contribute genes to the next generation |
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Stabilizing Selection |
Extreme phenotypes are selected against; mean phenotype has the highest fitness |
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Disruptive Selection |
Favors selection of 2 or more different phenotypes in populations that occupy a diverse environment |
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Directional Selection |
Favors individuals at one extreme; may occur due to a change in environment, introduction of a new allele, or both |
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Balancing Selection |
Favors maintenance of both alleles in a population; heterozygote advantage |
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Genetic Drift |
Changes in allele frequency due to random chance; more susceptible in small populations |
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Bottleneck Effect |
A population decreases dramatically in size due to a natural event; individuals are lost from the population without regard to genotype; the population rebounds, but genetic composition is altered |
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Founder Effect |
A small group of individuals separate from a larger population; allele frequencies of the founder population are not representative of the original population |
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Migration |
Gene flow occurs when individuals migrate between populations with different allele frequencies; increases genetic variation within the receiving population & reduces genetic variation between populations |
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Random Mating |
Individuals choose mates irrespective of genotype & phenotype |
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Positive Assortative Mating |
Individuals prefer a partner with the same trait. Increases frequency of homozygotes, decreases frequency of heterozygotes |
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Negative Assortative Mating |
Individuals prefer a partner with a different trait. Increases the frequency of heterozygotes, and decreases the frequency of homozygotes |
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Inbreeding |
Mating between 2 genetically related individuals; concentrates rare, recessive alleles in a population, decreasing fitness |
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Polygenic Traits |
Traits that are determined by more than one gene |
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Complex traits |
Influenced by several genes as well as environmental factors |
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Continuous Traits |
Do not fall into discrete categories |
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Meristic Traits |
Can be counted & expressed in whole numbers |
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Threshold Traits |
Traits that show genetic predisposition, but ultimately determined by the contribution of several genes & environment. Ex: diabetes, heart disease |
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Quantitative Traits |
Can be described numerically. Ex: height, weight, metabolic rate |
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Normal Distribution |
Most individuals have the mean phenotype & there is symmetrical phenotypic variation at either side of the mean. On a graph, it is a bell shaped curve with symmetrical variation about the mean |
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Variance |
Measure of how much phenotypic variation is present in a population |
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Co-variance |
Describes the relationship between 2 variables within a group |
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Correlation Coefficient |
Measures the strength of association between 2 variables. This value ranges between +1 & -1 & indicates how 2 factors can vary in relation to each other. |
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Correlation Coefficient Values |
If r > 0 As one factor increases, the other increases If r = 0 The 2 factors are not related If r < 0 As one factor increases, the other factor decreases |
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Broad Sense Heritability |
An estimate of how much phenotypic variation about the mean is due to genetic factors (it is the ratio of variance due to genetic factors over total variance) |
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Narrow Sense Heritability |
An estimate of how much phenotypic variance in a population can be predictably inherited (it is the ration of variance due to additive genetic factors over total phenotypic variance) |
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Polymerase Chain Reaction |
Used to amplify a target DNA sequence to produce many copies |
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What 4 components are required as starting material for any PCR? |
Template DNA DNA nucleotides DNA primers DNA Taq polymerase |
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What are the 3 basic steps that are repeated with each cycle? |
1) Denaturation: the template DNA strands are separated by heating the DNA to 95°C 2) Primer Annealing: the temperature is lowered to 55-62°C to allow the primers to anneal to the template strand 3) Primer Extension: the temperature is raised to 72°C & Taq polymerase synthesizes a new DNA strand |
