Chapter 7 Flashcards
(115 cards)
1
Q
What allows evolution by natural selection
A
genetic variation
2
Q
Deoxyribonucleic acid (DNA):
A
a molecule composed of two strands of nucleotides that are wound together into a double helix
3
Q
a molecule composed of two strands of nucleotides that are wound together into a double helix
A
Deoxyribonucleic acid (DNA)
4
Q
what is each strand of DNA composed of?
A
nucleotides
5
Q
Each nucleotide has
A
a sugar, a phosphate group, and one of four nitrogenous bases
6
Q
nitrogenous bases
A
adenine (A), thymine (T), cytosine (C), and guanine (G)
7
Q
what does the order of nitrogenous bases codes for
A
genetic information
8
Q
chromosomes
A
compact structures consisting of long strands of DNA wound around proteins
9
Q
compact structures consisting of long strands of DNA wound around proteins
A
chromosomes
10
Q
what is a chromosome
A
a really long section of DNA, which is made of nucleotide unites
11
Q
what are genes
A
different regions of DNA that code for particular proteins, which in
turn affect particular traits
12
Q
alleles
A
different forms of a particular gene
13
Q
different forms of a particular gene
A
alleles
14
Q
what can changes in alleles create
A
differences in an organism’s phenotype
15
Q
polygenic
A
when a single trait is affected by several genes; enables phenotypes to span a range of values in a population (e.g., human body height)
16
Q
when a single trait is affected by several genes; enables phenotypes to span a range of values in a population (e.g., human body height)
A
polygenic
17
Q
phenotype distributions are oftn
A
bell-shaped
18
Q
pleiotropy
A
when a single gene affects multiple traits
19
Q
when a single gene affects multiple traits
A
pleiotropy
20
Q
epistasis
A
when the expression of one gene is controlled by another gene
21
Q
when the expression of one gene is controlled by another gene
A
epistasis
22
Q
every individual produced by sexual individuals has two copies of each gene,
A
one from its mother and one from its father
23
Q
heterozygous
A
when an individual has two different alleles of a particular gene
24
Q
homozygous
A
when an individual has two identical alleles of a particular gene
25
codominant
when two alleles both contribute to the phenotype
26
dominant
an allele that masks the expression of the other allele
27
recessive
an allele whose expression is masked by another allele; most harmful alleles are recessive
28
gene pool
collection of alleles from all individuals in a population
29
sexual reproduction combines haploid sex cells of two parents to from new combinations of alleles that
code for novel phenotypes
30
Random assortment
the process of making haploid gametes in which the combination of alleles that are placed into a given gamete could be any combination of those possessed by the diploid parent
31
the process of making haploid gametes in which the combination of alleles that are placed into a given gamete could be any combination of those possessed by the diploid parent
random assortment
32
mutation
a random change in the sequence of nucleotides (sugar, phosphate and nitrogen base) in regions of DNA that controls the expression of a gene
33
a random change in the sequence of nucleotides (sugar, phosphate and nitrogen base) in regions of DNA that controls the expression of a gene
mutation
34
mutations can be silent
no detectable effect
35
other mutations may
alter the physical appearance of an organism, or have lethal effects
36
setting the stage for meiosis: crossing over
during prophase 1, homologous pairs join together (synapsis) and exchange genetic information
37
what does exchange of DNA during prophase I do
increases genetic variability - chromatids are no longer exact duplicates
38
What happens during metaphase
chromosomes line up in pairs, but they line up randomly (random assortment)
39
Types of mutations
1. point mutation
2. chromosome inversion
3. gene duplication
4. polyploidy
40
point mutation description
base-pair substitutions in DNA sequences
41
point mutation cause
chance errors during DNA synthesis or during repair of damaged DNA
42
point mutation significance
creates new alleles
43
chromosome inversion description
flipping of a chromosome segment, so that the order of genes along the chromosome is altered
44
chromosome inversion cause
breaks in DNA caused by radiation
45
chromosome inversion significance
alleles inside the inversion are "locked together" into a unit
46
gene duplication description
duplication of a short stretch of DNA, creating an additional copy of a gene
47
gene duplication cause
unequal crossing over during meiosis
48
gene duplication significance
the "extra" gene is free to mutate and perhaps gain new function
49
polyploidy description
addition of a complete set of chromosomes
50
polyploidy cause
errors in meiosis or (in plants) mitosis
51
polyploidy significance
can create new species
52
what can mutations cause in humans
fatal defects, diseases to become resistant to antibacterial drugs
53
Recombination
the reshuffling of genes that can occur as DNA is copied during meiosis and chromosomes exchange genetic material
54
the reshuffling of genes that can occur as DNA is copied during meiosis and chromosomes exchange genetic material
recombination
55
during meiosis
pairs of homologous chromosomes (one from each parent) can exchange DNA in a process called crossing over
56
crossing over can also occur between
nonhomologous chromosomes
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what does recombination do
helps the immune system rapidly evolve
58
Driving forces of evolution
1. mutations
2. genetic drift (founder effect, bottlenecks)
3. gene flow
4. non-random mating
5. natural selection (predation, parasitism, disease, competition, weather)
59
mutations that negatively impact physiological functions are not favored by selection, but
a small fraction can be beneficial
60
the more genes a species caries
the more likely at least one gene will mutate
61
Genetic drift
a process that occurs when genetic variation is lost due to random variation in mating, mortality, fecundity, and inheritance
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a process that occurs when genetic variation is lost due to random variation in mating, mortality, fecundity, and inheritance
Genetic drift
63
why is genetic drift more common in small populations
random events can have a disproportionately large effect on the frequencies of genes
64
Bottleneck effect
a reduction of genetic diversity in a population due to a large reduction in population size (e.g., from loss of food).
65
a reduction of genetic diversity in a population due to a large reduction in population size (e.g., from loss of food).
Bottleneck effect
66
survivors of bottleneck effect
carry a fraction of the genetic diversity from the original population
67
bottleneck effects can prevent a population from
adapting to future environmental changes, such as emergent disease
68
Founder effect
when a small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation
69
when a small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation
Founder effect
70
Genetic drift can cause
additional reductions in genetic variation
71
Genetic variation remains low until
enough time has passed to accumulate new mutations
72
Selection
the process by which certain phenotypes are favored to survive and reproduce over other phenotypes
73
the process by which certain phenotypes are favored to survive and reproduce over other phenotypes
Selection
74
Stabilizing selection
when individuals with intermediate phenotypes have higher survival and reproductive success than those with extreme phenotypes
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when individuals with intermediate phenotypes have higher survival and reproductive success than those with extreme phenotypes
Stabilizing selection
76
progeny
has a more narrow distribution of phenotypes
77
stabilizing selection occurs when
the environment is relatively unchanging
78
stabilizing selection generates
little evolutionary change
79
directional selection
when individuals with extreme phenotypes experience higher fitness than the average population phenotype
80
when individuals with extreme phenotypes experience higher fitness than the average population phenotype
directional selection
81
Disruptive selection
when individuals with either extreme phenotype experience higher fitness than individuals with an intermediate phenotype
82
when individuals with either extreme phenotype experience higher fitness than individuals with an intermediate phenotype
Disruptive selection
83
by removing the intermediate phenotype
genetic and phenotypic variation increases
84
at what level does microevolution operate on
population level
85
at what levels can evolution be studied at
microevolutionary and macroevolutionary
86
Microevolution
the evolution of populations; affected by random processes and selection
87
the evolution of populations; affected by random processes and selection
Microevolution
88
Artificial selection
Selection in which humans decide which individuals will breed; breeding is done with a preconceived goal for the traits in the population (e.g., dogs, wild mustard).
89
Selection in which humans decide which individuals will breed; breeding is done with a preconceived goal for the traits in the population (e.g., dogs, wild mustard).
Artificial selection
90
what does natural selection favor
trait combinations that provide higher fitness to an individual
91
what kind of process is natural selection
ecological process
92
ecological process
individuals interact with their environment, and traits that lead to greater fitness in an environment are passed on
93
Industrial melanism
a phenomenon in which industrial activities cause habitats to become darker due to pollution; individuals possessing darker phenotypes
are favored by selection
94
a phenomenon in which industrial activities cause habitats to become darker due to pollution; individuals possessing darker phenotypes
are favored by selection
Industrial melanism
95
what level does macroevolution operate at
species level and higher levels of taxonomic organization
96
Macroevolution
evolution at higher levels of organization including species, genera, families, orders, and phyla
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evolution at higher levels of organization including species, genera, families, orders, and phyla
Macroevolution
98
speciation
the evolution of a new species
99
the evolution of a new species
speciation
100
Phylogenetic trees
hypothesized patterns of relatedness among different groups such as populations, species, or genera; depict which groups evolved from other groups
101
hypothesized patterns of relatedness among different groups such as populations, species, or genera; depict which groups evolved from other groups
Phylogenetic trees
102
Allopatric speciation
the evolution of new species through the process of geographic isolation
103
the evolution of new species through the process of geographic isolation
Allopatric speciation
104
Occurs when a single population is separated by a geographic event (e.g., formation of a river).
Allopatric speciation
105
what do isolated populations experience
genetic drift, founder effects, and novel natural selection pressures; populations evolve separately
106
Sympatric speciation
the evolution of new species without geographic isolation
107
the evolution of new species without geographic isolation
Sympatric speciation
108
sympatric speciation may occur as a result of:
1. habitat isolation
2. sexual preference
3. polyploidy
109
polyploid
a species that contains three or more sets of chromosomes; can also give rise to sympatric speciation.
110
a species that contains three or more sets of chromosomes; can also give rise to sympatric speciation.
polyploid
111
when do polyploids arise
when homologous chromosomes fail to separate during meiosis, producing diploid gametes. If a diploid egg is fertilized by a haploid sperm, a polyploid will develop
112
a polyploid is unable to breed when
a diploid is genetically distinct from its parents
113
homologous structures
skeletal elements of an animal/organism that, by virtue of similarity, suggest connection to a common ancestor
114
analogous structures
similar structures that evolved independently in two living organisms to serve the same purpose
115
convergent evolution
independent evolution of similar features in a species of different periods in time line
