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AP Biology Chapter 23 Flashcards

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6299762866MutationsA change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity. New genes and new alleles.0
6299767971Point mutationA change in a single base pair of a DNA sequence in a gene. Can be silent or lead to diseases such as sickle-cell disease.1
6299775703Chromosomal mutationdelete, disrupt, duplicate or rearrange many loci at once. Often, but not always harmful. Duplications can create expanded genome with new genes that may build over generations and take on new functions.2
6299836969Sexual recombinationcreates most genetic diversity within a population.3
6299858905Crossing overProcess in which homologous chromosomes exchange portions of their chromatids during prophase I meiosis.4
6299863046Independent assortmentprinciple that genes do not influence each other's inheritance because they are separated independently during meiosis. 2 to 23rd power different combinations possible in gamete formation5
6299883551FertilizationProcess in sexual reproduction in which male and female reproductive cells join to form a new cell. 2^23 x 2^23 different possible combinations6
6299915780Population geneticsStudy of allele frequency distribution and change under the influence of evolutionary processes.7
6299918689PopulationA group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.8
6299921378Gene poolAll the genes, including all the different alleles for each gene, that are present in a population at any one time9
6299926620Fixed alleleOccurs when the frequency of an allele reaches 100% , all of the members of the population are homozygous. Only 1 allele exists for a gene and results in less genetic diversity.10
6299938236Hardy-Weinberg principleused to describe a population that is not evolving. principle that states that allele frequencies in a population remain constant unless one or more factors ( other than mMendelian segregation and the recombination)cause those frequencies to change.11
6299969172Hardy-Weinberg equilibriumEvolution is not occurring in a population; the rules for this are no mutations, no gene flow, no genetic drift, no natural selection, and only random mating.12
6299984473Hardy-Weinberg equationp + q = 1, p2 + 2pq + q2 = 1;( 3 alleles :1 = (p + q + r)^2 = p^2 + q^2 + r^2 + 2pq + 2pr + 2qr) p=dominant allele q=recessive allele r(if present)=3rd allele(co-dominant or incomplete)13
6300085294Natural SelectionA process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits. Environment is agent.14
6300086884Genetic DriftA change in the allele frequency of a population as a result of chance events rather than natural selection.15
6300093115Founder effectGenetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.16
6300095245Bottleneck effectGenetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.17
6300097511Gene flowWhen a population gains or loses alleles., movement of alleles into or out of a population due to the migration of individuals to or from the population. lots = populations are more similar18
6300104189Relative fitnessThe contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population. measure only by reproductive success.19
6300106995Directional selectionForm of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve20
6300109010Disruptive selectionNatural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes.21
6300112538Stabalizing selectionA natural selection that favors average individuals in a population; results in a decline in population variation22
6300117945Sexual selectionA form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.23
6300120831Diploidy2N condition maintains and shelters a hidden pool of alleles that may not be suitable for present conditions but that could be advantageous if conditions change24
6300124171Heterozygote advantageGreater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools. Ex. sickle-cell and malaria25

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