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52 Cards in this Set
- Front
- Back
adaptive radiation
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speciation in isolated habitats leading to a diverse biota (collection of organisms)
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gigantism
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species become larger on islands than their ancestors
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dwarfism
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species become smaller on islands than their ancestors
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theory
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set of hypotheses to explain some phenomenon in nature; consists of pattern and process
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Evolution (pattern and process)
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pattern - all organisms share a common ancestry
process - organisms change over time, mostly due to natural selection |
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Darwin's Theory of Natural Selection
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1.) There is variation within a species
2.) Some of this variation is heritable 3.) More offspring are produced than can survive 4.) Those variants best able to win the struggle for existence will survive and pass on their traits to their offspring |
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chromosome
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material that contains DNA and associated proteins
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sex chromosomes
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occur in many animals and plants, vary according to sex
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autosomes
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chromosomes that don't vary by sex
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gene
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portion of DNA that determines a particular trait (produces a tRNA or rRNA molecule)
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locus
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location on chromosome where gene is found
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allele
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variant of a gene (allele for blue eyes and an allele for brown eyes)
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diploid
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having two copies of every chromosome (2n)
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haploid
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single copy of every chromosome (1n)
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gametes
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haploid cells specialized for genetic fusion (eggs & sperm)
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zygote
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product of sexual fusion of gametes (2n)
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homozygous
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condition where two alleles for a gene are the same (AA)
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heterozygous
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condition where two alleles for a gene are different (Aa)
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genotype
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genetic constitution of an organism
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phenotype
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observable traits of an organism (morphological, physiological, and behavioral)
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true-breeding lines
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always produced the same phenotype (homozygous)
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self-compatible
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pollen can go to ovule, right in self plant; self-fertilizing
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reciprocal cross
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white cat w/grey by grey cat w/white
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meiosis
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reduction division, produces gametes (reproductive cells) 2n to 1n
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Principle of Segregation
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alleles of parent sort independently and in equal proportions in meiosis
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hemizygous
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only has one possible place for an allele (single copy of a gene)
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non-disjunction
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one chromosome doesn't split during meiosis
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crossing-over
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inner arms of sister chromatids, but not outer arms, results in two recombinant and two nonrecombinant chromatids
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chiasma
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place where crossing-over occurs
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incomplete dominance
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blending of traits (red and white flowers make pink flowers)
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codominance
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both alleles are expressed (red flowers and white flowers make red/white flowers, tie-dyed)
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epistasis
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masking of expression of one locus by a particular genotype of second locus (results in less phenotypes than expected)
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pleitropy
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single gene affects many phenotypic traits
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penetrance
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expression of a particular phenotype by a genotype
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expressivity
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degree to which a phenotype is expressed
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transgenic mice
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putting a human gene into a mouse
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phenotypic plasticity
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some facet of environment influences expression of one or more phenotypic traits
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evolution
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any change in allele frequency
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gene pool
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all alleles in a population
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mechanisms of evolution
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ways of altering allele frequency
1.) selection 2.) mutation 3.) gene flow (migration) 4.) genetic drift (sampling error, only small populations) |
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Hardy-Weinberg Principle
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In an infinitely large population, where random breeding occurs free from selection, mutation, and migration then
1.) allele frequencies won't change 2.) genotypes will be distributed with p^2+2pq+q^2 = 1 |
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assortative mating
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type of non-random breeding
like attracted to like, leads to underrepresentation of heterozygotes |
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disassortative mating
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type of non-random breeding
opposites attracting, leads to overrepresentation of heterozygotes |
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genetic drift
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any change in allele frequency due to chance (random process), causes decrease in heterozygotes
only important in small population sizes |
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founder effect
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If new population is formed then by chance new population is likely to have different allele frequencies
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bottleneck effect
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when a population is reduced to a few individuals they cannot represent all of the alleles of the original populations gene pool
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gene flow
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homogenization of gene pools, makes populations more like one another
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mutation
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random changes in allele frequencies, result from copying errors
only mechanism that produces new alleles |
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point mutation
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includes silent, missense (one different protein coded for), and nonssense mutations (changes stop codon, too early or too late)
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directional selection
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before selection normal bell curve, after selection less variability and entire curve moves to one direction
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stabilizing selection
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selecting against extremes, before selection normal curve, after mean grows and reduction in variability
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disruptive selection
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selecting against mean, before selection normal curve, after extremes flourish
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