Key Terms Bi164

Front 1

adaptive radiation

Back 1

speciation in isolated habitats leading to a diverse biota (collection of organisms)

Front 2

gigantism

Back 2

species become larger on islands than their ancestors

Front 3

dwarfism

Back 3

species become smaller on islands than their ancestors

Front 4

theory

Back 4

set of hypotheses to explain some phenomenon in nature; consists of pattern and process

Front 5

Evolution (pattern and process)

Back 5

pattern - all organisms share a common ancestry

process - organisms change over time, mostly due to natural selection

Front 6

Darwin's Theory of Natural Selection

Back 6

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

Front 7

chromosome

Back 7

material that contains DNA and associated proteins

Front 8

sex chromosomes

Back 8

occur in many animals and plants, vary according to sex

Front 9

autosomes

Back 9

chromosomes that don't vary by sex

Front 10

gene

Back 10

portion of DNA that determines a particular trait (produces a tRNA or rRNA molecule)

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locus

Back 11

location on chromosome where gene is found

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allele

Back 12

variant of a gene (allele for blue eyes and an allele for brown eyes)

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diploid

Back 13

having two copies of every chromosome (2n)

Front 14

haploid

Back 14

single copy of every chromosome (1n)

Front 15

gametes

Back 15

haploid cells specialized for genetic fusion (eggs & sperm)

Front 16

zygote

Back 16

product of sexual fusion of gametes (2n)

Front 17

homozygous

Back 17

condition where two alleles for a gene are the same (AA)

Front 18

heterozygous

Back 18

condition where two alleles for a gene are different (Aa)

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genotype

Back 19

genetic constitution of an organism

Front 20

phenotype

Back 20

observable traits of an organism (morphological, physiological, and behavioral)

Front 21

true-breeding lines

Back 21

always produced the same phenotype (homozygous)

Front 22

self-compatible

Back 22

pollen can go to ovule, right in self plant; self-fertilizing

Front 23

reciprocal cross

Back 23

white cat w/grey by grey cat w/white

Front 24

meiosis

Back 24

reduction division, produces gametes (reproductive cells) 2n to 1n

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Principle of Segregation

Back 25

alleles of parent sort independently and in equal proportions in meiosis

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hemizygous

Back 26

only has one possible place for an allele (single copy of a gene)

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non-disjunction

Back 27

one chromosome doesn't split during meiosis

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crossing-over

Back 28

inner arms of sister chromatids, but not outer arms, results in two recombinant and two nonrecombinant chromatids

Front 29

chiasma

Back 29

place where crossing-over occurs

Front 30

incomplete dominance

Back 30

blending of traits (red and white flowers make pink flowers)

Front 31

codominance

Back 31

both alleles are expressed (red flowers and white flowers make red/white flowers, tie-dyed)

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epistasis

Back 32

masking of expression of one locus by a particular genotype of second locus (results in less phenotypes than expected)

Front 33

pleitropy

Back 33

single gene affects many phenotypic traits

Front 34

penetrance

Back 34

expression of a particular phenotype by a genotype

Front 35

expressivity

Back 35

degree to which a phenotype is expressed

Front 36

transgenic mice

Back 36

putting a human gene into a mouse

Front 37

phenotypic plasticity

Back 37

some facet of environment influences expression of one or more phenotypic traits

Front 38

evolution

Back 38

any change in allele frequency

Front 39

gene pool

Back 39

all alleles in a population

Front 40

mechanisms of evolution

Back 40

ways of altering allele frequency

1.) selection
2.) mutation
3.) gene flow (migration)
4.) genetic drift (sampling error, only small populations)

Front 41

Hardy-Weinberg Principle

Back 41

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

Front 42

assortative mating

Back 42

type of non-random breeding

like attracted to like, leads to underrepresentation of heterozygotes

Front 43

disassortative mating

Back 43

type of non-random breeding

opposites attracting, leads to overrepresentation of heterozygotes

Front 44

genetic drift

Back 44

any change in allele frequency due to chance (random process), causes decrease in heterozygotes

only important in small population sizes

Front 45

founder effect

Back 45

If new population is formed then by chance new population is likely to have different allele frequencies

Front 46

bottleneck effect

Back 46

when a population is reduced to a few individuals they cannot represent all of the alleles of the original populations gene pool

Front 47

gene flow

Back 47

homogenization of gene pools, makes populations more like one another

Front 48

mutation

Back 48

random changes in allele frequencies, result from copying errors

only mechanism that produces new alleles

Front 49

point mutation

Back 49

includes silent, missense (one different protein coded for), and nonssense mutations (changes stop codon, too early or too late)

Front 50

directional selection

Back 50

before selection normal bell curve, after selection less variability and entire curve moves to one direction

Front 51

stabilizing selection

Back 51

selecting against extremes, before selection normal curve, after mean grows and reduction in variability

Front 52

disruptive selection

Back 52

selecting against mean, before selection normal curve, after extremes flourish