Chapter 9 Flashcards
(159 cards)
1
Q
Term/Front
A
Definition/Back
2
Q
What is a gene pool?
A
The collection of all the genes and alleles within a specific population.
3
Q
How can allele frequencies be represented?
A
By the proportion of a particular allele appearing at a certain gene locus in a gene pool.
4
Q
What is the significance of a larger and more diverse gene pool?
A
It contains a greater variety of genes and alleles, leading to increased genetic diversity.
5
Q
What is an allele?
A
An alternate form of a gene.
6
Q
What does a gene code for?
A
A section of DNA that carries the code to make a protein.
7
Q
What is a population in the context of genetics?
A
A group of individuals of the same species living in the same location.
8
Q
What does allele frequency refer to?
A
The proportion of certain alleles in a gene pool.
9
Q
Define genotype.
A
The genetic composition of an organism at a particular gene locus.
10
Q
What is phenotype?
A
The physical or biochemical characteristics of an organism that are the result of gene expression and the environment.
11
Q
What is genetic diversity?
A
The variation in genetic makeup or alleles within a population.
12
Q
What are mutations?
A
Permanent changes to the DNA sequence of an individual that can introduce new alleles into a population.
13
Q
How can mutations occur?
A
Mutations can occur spontaneously or be induced by agents known as mutagens, such as UV radiation.
14
Q
What are the classifications of mutations based on their effect on survivability?
A
Mutations can be classified as advantageous, neutral, or deleterious.
15
Q
What is a mutagen?
A
An agent that can cause mutations in DNA.
16
Q
What does deleterious mean in genetics?
A
Used to describe alleles that have an overall negative effect on individual fitness when expressed.
17
Q
Why are mutations evolutionarily significant?
A
They create and introduce new alleles into a population, thereby increasing genetic diversity.
18
Q
When is a mutation considered heritable?
A
A mutation is heritable if it occurs in an individual’s germline cells.
19
Q
What are the two categories of mutations based on their effect on nucleotide bases?
A
Mutations can be categorised as point mutations or block mutations.
20
Q
What is a point mutation?
A
A point mutation is a mutation that alters a single nucleotide in a DNA sequence.
21
Q
What are the types of point mutations based on their effects on proteins?
A
Point mutations can be silent, missense, or nonsense mutations.
22
Q
What is a silent mutation?
A
A silent mutation is a mutation in which a nucleotide is substituted for another, changing the codon but still coding for the same amino acid, resulting in no effect on protein structure.
23
Q
What is a missense mutation?
A
A missense mutation is a mutation in which a nucleotide is substituted for another, changing the codon and coding for a different amino acid, potentially affecting protein structure.
24
Q
What triggers a frameshift mutation?
A
The addition or deletion of a single nucleotide triggers a frameshift mutation.
25
What is a block mutation?
A block mutation is a mutation that affects a large chunk of DNA or an entire gene.
26
What is the difference between germline cells and somatic cells?
Germline cells are involved in the generation of gametes, while somatic cells are any cells in an organism that are not germline cells.
27
What is a nonsense mutation?
A mutation where a nucleotide is substituted for another, changing the codon to a stop codon and prematurely ceasing translation of the gene’s mRNA, affecting protein structure.
28
What characterizes a frameshift mutation?
A mutation that involves the insertion or deletion of one or two nucleotides, altering every codon from that point forward.
29
What does the term 'degenerate' refer to in genetics?
A property of the genetic code indicating that a single amino acid can be coded for by more than one codon.
30
What is meant by the reading frame in genetics?
The order in which nucleotide triplets or codons are divided into a consecutive, non-overlapping sequence.
31
What are block mutations?
Mutations that involve changes to larger sections of DNA, altering the structure of a chromosome by deleting, duplicating, inverting, or translocating a cluster of nucleotides, potentially affecting multiple genes.
32
What is aneuploidy?
Aneuploidy refers to a chromosomal abnormality in which an organism possesses an incorrect number of total chromosomes caused by the addition or loss of an individual chromosome.
33
What is polyploidy?
Polyploidy refers to a chromosomal abnormality in which an organism has an incorrect number of sets of each chromosome, meaning there is an entire set of chromosomes added or missing.
34
How do mutations affect genetic variation?
Mutations are capable of introducing new alleles into a population, making them a key source of genetic variation and evolutionarily significant.
35
What are environmental selection pressures?
Environmental selection pressures are factors within the environment that influence the survivability of a species, such as predation, disease, competition, and climate change.
36
How do environmental selection pressures affect natural selection?
They promote the survival of individuals best adapted to the environment, leading to the passing on of their alleles through natural selection.
37
What is meant by genetic fitness in the context of environmental selection pressures?
Genetic fitness refers to the likelihood of an organism to survive and reproduce based on its advantageous phenotype, which is influenced by certain alleles.
38
What role does variation play in natural selection?
Variation allows for both advantageous and disadvantageous alleles to exist, enabling the selection of alleles that confer an advantage and the removal of those that do not.
39
What are the four basic conditions that facilitate natural selection?
The four basic conditions include variation within the population, heritability of advantageous alleles, differential survival and reproduction, and environmental selection pressures.
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What is environmental selection pressure?
A factor in the environment that impacts an organism’s ability to survive and reproduce, such as limited resources, deforestation, changing temperature, or predation.
41
What is competition in ecological terms?
Interactions between organisms in which both are negatively impacted when vying for the same limited resource, which can occur within or between species.
42
How does natural selection function?
It is a mechanism through which organisms that are better adapted to their environment have an increased chance of surviving and passing on their alleles.
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What does fitness measure in an organism?
It measures how well an organism survives and reproduces in its environment.
44
What is an advantageous phenotype?
A biochemical, physical, or behavioral trait that increases an organism’s fitness in its local environment.
45
What is selective advantage?
An organism conferred a beneficial allele, which increases its chances of survival against a specific environmental selection pressure.
46
What does allele frequency refer to?
The proportion of certain alleles in a gene pool.
47
What is heritability?
The transmission from parent to offspring, which is encoded in genes.
48
What defines a population in ecological terms?
A group of organisms of the same species living in the same area.
49
What is a disadvantageous allele?
An allele that encodes for a biochemical, physical, or behavioral trait that lowers an individual’s fitness in its local environment.
50
How do environmental selection pressures affect genetic diversity?
Environmental selection pressures can reduce genetic diversity by favoring fitter individuals with advantageous phenotypes, leading to increased allele frequencies of those traits and decreased diversity.
51
What role do environmental selection pressures play in natural selection?
Environmental selection pressures drive the adaptation of a population by determining which phenotypes are fitter and advantageous, influencing which traits are passed on to the next generation.
52
What happens to allele frequencies as advantageous traits become more common?
As advantageous traits become more common, the allele frequencies change, with the frequency of the advantageous allele increasing, potentially leading to the evolution of the species.
53
Why is genetic diversity important for the survivability of a species?
Genetic diversity is crucial for survivability because a population with greater variation in alleles has a higher chance of possessing favorable alleles that aid survival under new selection pressures.
54
What risks do populations with low genetic diversity face?
Populations with low genetic diversity are at a higher risk of extinction due to their inability to adapt to changing environmental selection pressures.
55
How does population size relate to genetic diversity?
Small populations are more likely to have low genetic diversity compared to large populations, making them more susceptible to environmental pressures.
56
What is a consequence of inbreeding in populations with low genetic diversity?
Inbreeding is more common in populations with low genetic diversity, which can further reduce genetic variation and increase extinction risk.
57
What is the impact of low genetic diversity on a population's ability to adapt to environmental selection pressures?
Low genetic diversity can lead to a scarcity of advantageous alleles, making it difficult for the population to adapt to new environmental pressures, such as drought.
58
How does inbreeding affect genetic diversity in populations?
Inbreeding is more common in populations with low genetic diversity, which can increase the prevalence of disadvantageous alleles.
59
What role do environmental selection pressures play in natural selection?
Environmental selection pressures facilitate natural selection by favoring individuals that are best adapted to their environment, leading to greater reproductive success.
60
What happens to allele frequencies in a population as fitter traits become more common?
As fitter traits become more common, the allele frequencies and genetic diversity within the population change.
61
Define genetic diversity.
Genetic diversity is the variation in genetic makeup or alleles within a population.
62
What is evolution in the context of population genetics?
Evolution is the change in the genetic makeup of a population over successive generations.
63
What is the definition of gene flow?
Gene flow is the transfer of genetic material between populations, which can increase genetic diversity and affect allele frequencies.
64
How does genetic drift affect small populations?
Genetic drift can lead to significant changes in allele frequencies in small populations, potentially resulting in the loss of genetic diversity.
65
What role does environmental selection pressure play in evolution?
Environmental selection pressures influence which individuals survive and reproduce, shaping the evolution of species over time.
66
What is the significance of mutations in evolution?
Mutations introduce new genetic variations, which can be beneficial, neutral, or harmful, and are a primary source of genetic diversity in populations.
67
How does natural selection contribute to speciation?
Natural selection can lead to speciation by favoring traits that adapt populations to different environments, eventually resulting in reproductive isolation.
68
What is genetic drift?
Genetic drift involves changes to a population’s allele frequencies due to sudden and random occurrences.
69
What are the two main effects through which genetic drift occurs?
Genetic drift occurs through either the bottleneck effect or the founder effect.
70
What is the bottleneck effect?
The bottleneck effect occurs when a large portion of a population is wiped out by a random event, leading to a significant decrease in population size and allele frequencies.
71
How does the bottleneck effect impact genetic diversity?
The bottleneck effect can lead to the loss of unique alleles, resulting in a new population with lower genetic diversity than the pre-disaster population.
72
What is the founder effect?
The founder effect is the reduction in genetic diversity that occurs when a population is derived from a small unrepresentative sample of the original population.
73
What is allele frequency?
Allele frequency is the proportion of certain alleles in a gene pool.
74
What is the founder effect?
The founder effect occurs when a small unrepresentative sample of individuals separates from a larger population to colonise a new region and start a new population.
75
How does the founder effect impact genetic diversity?
The founder effect leads to a new population with significantly lower genetic diversity compared to the original population.
76
What is an unrepresentative sample?
An unrepresentative sample is a small selection of individuals from a larger group that does not reflect the characteristics of the larger group.
77
What are the risks associated with reduced genetic diversity?
The risks include inbreeding, which keeps harmful alleles in the gene pool, and lower adaptive potential, making populations vulnerable to new selection pressures.
78
Why are smaller populations more susceptible to genetic drift?
Smaller populations typically have lower genetic diversity compared to larger populations, making them more susceptible to the effects of genetic drift.
79
What is the effect of genetic drift on larger populations?
Larger populations are more resistant to the effects of genetic drift due to their higher genetic diversity.
80
What happens to a population's gene pool if a beetle dies before reproducing?
The genes of that beetle are lost from the gene pool, equating to a percentage loss depending on the population size.
81
How does the size of a population affect the impact of random events on its gene pool?
In larger populations, the impacts of random events are reduced, as the loss of genes represents a smaller percentage of the overall gene pool.
82
What is gene flow?
Gene flow involves the introduction or removal of alleles between populations through migration or interbreeding.
83
What are the two processes involved in gene flow?
Migration and interbreeding.
84
What is immigration in the context of gene flow?
Immigration is the movement of individuals into a population, adding their alleles to the gene pool.
85
What is emigration in the context of gene flow?
Emigration is the movement of individuals out of a population, removing their alleles from the gene pool.
86
How does gene flow affect genetic diversity?
Gene flow can introduce or remove alleles from a population, thereby increasing or decreasing genetic variation.
87
How does immigration affect allele frequencies in a population?
Immigration increases genetic diversity in a population by bringing in new alleles, especially pronounced in smaller populations.
88
What is the effect of emigration on a population's genetic diversity?
Emigration decreases genetic diversity by removing alleles from a population's gene pool, with more pronounced effects in smaller populations.
89
What happens when individuals with unique alleles interbreed?
Genetic diversity increases as new alleles can be permanently added to a population's gene pool, provided the alleles are not selected against.
90
What is the difference between genetic drift and gene flow?
Genetic drift involves random events that alter a population's gene pool, while gene flow involves the movement of alleles into or out of a population.
91
How do genetic drift and gene flow influence allele frequencies?
Genetic drift reduces a population's gene pool, while gene flow can either increase or decrease genetic diversity.
92
What is speciation?
Speciation is the process by which populations genetically diverge until they become distinct species.
93
What are the two main types of speciation?
The two main types of speciation are allopatric speciation and sympatric speciation.
94
What is allopatric speciation?
Allopatric speciation is the geographic separation of a population from a parent population resulting in the formation of a new species.
95
What is sympatric speciation?
Sympatric speciation is the divergence of a species from an original species without the presence of a geographical barrier.
96
How can individuals be recognized as different species?
Individuals are recognized as different species if they can no longer interbreed with one another to produce viable and fertile offspring.
97
What are isolating mechanisms?
Isolating mechanisms are the mechanisms which prevent species from interbreeding to produce fertile and viable offspring.
98
What are the two categories of isolating mechanisms?
The two categories of isolating mechanisms are pre-reproductive and post-reproductive isolating mechanisms.
99
What role do mutations, natural selection, genetic drift, and gene flow play in speciation?
These processes influence the frequency of alleles, leading to changes in the genetic composition and genetic diversity of a population, which can result in speciation.
100
What are subspecies?
Subspecies are individuals phenotypically different from their original population that can still interbreed to produce viable and fertile offspring.
101
What are the two types of reproductive isolating mechanisms?
Pre-reproductive and post-reproductive isolating mechanisms.
102
What is allopatric speciation?
The formation of a new species as a result of a geographical barrier.
103
What role do geographical barriers play in allopatric speciation?
They isolate populations from each other, preventing gene flow and allowing genetic differences to accumulate.
104
What can cause genetic differences to accumulate in geographically separated populations?
The presence of different selection pressures.
105
What is a geographic barrier?
A physical factor that prevents gene flow and stops two populations from breeding together.
106
What is the primary mechanism behind the formation of different species of Galápagos finches?
The primary mechanism is allopatric speciation, as the islands are separated by the ocean, preventing gene flow and allowing for different selection pressures.
107
How many species of Galápagos finches are currently known?
There are currently 18 known species of Galápagos finches.
108
What role do different food sources play in the evolution of Galápagos finches?
Different food sources on each island create unique selection pressures that select for different phenotypes, such as beak shape, leading to genetic differences and speciation.
109
What is the difference between allopatric and sympatric speciation?
Allopatric speciation occurs due to geographical barriers preventing gene flow, while sympatric speciation occurs within the same geographical location without such barriers.
110
What is the significance of geographical barriers in allopatric speciation?
Geographical barriers prevent gene flow between populations, allowing for the accumulation of genetic differences and the eventual formation of new species.
111
What is sympatric speciation and how can it arise from genetic abnormalities?
Sympatric speciation can arise from genetic abnormalities during gamete formation, producing polyploid variants with differences in chromosome sets. For example, a diploid parent may produce diploid gametes, leading to the formation of a tetraploid organism after fertilization, which can be a new species if it produces viable offspring.
112
Why are plants more tolerant to changes in chromosome sets compared to humans and animals?
Plants are generally more tolerant to changes in their sets of chromosomes, which allows for the occurrence of polyploidy and sympatric speciation, whereas errors in chromosome sets in humans and animals often lead to embryo death.
113
What role does soil pH play in the sympatric speciation of Howea palms?
Soil pH differences acted as a catalyst for the sympatric speciation of Howea palms, with Howea belmoreana thriving in low pH soils and Howea forsteriana in high pH soils, leading to ecological divergence.
114
What reproductive isolation mechanism developed in Howea forsteriana?
Physiological differences, such as changes in flowering times, developed in Howea forsteriana, serving as a reproductive isolation mechanism that prevented interbreeding with Howea belmoreana.
115
What is polyploidy?
Polyploidy is when an organism contains additional sets of chromosomes in its genome, which can lead to the formation of new species, particularly in plants.
116
What is the difference between allopatric and sympatric speciation?
Allopatric speciation involves a geographical barrier that inhibits gene flow, while sympatric speciation occurs in populations existing in the same geographical area.
117
What evidence suggests that speciation on Lord Howe Island may have occurred sympatrically?
The small size of Lord Howe Island makes geographical isolation unlikely, supporting the idea of sympatric speciation.
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What role do genetic differences play in the formation of a new species?
When populations accumulate sufficient genetic differences and can no longer interbreed to produce viable and fertile offspring, a new species is formed.
119
What questions remain about the speciation event on Lord Howe Island?
Some researchers suggest that changes in flowering times may have arisen after the speciation event, rather than before, indicating areas for further investigation.
120
What is selective breeding?
Selective breeding, also known as artificial selection, is the process by which humans can select or remove particular traits from a population by directly controlling the breeding of animals or plants.
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What are the similarities between selective breeding and natural selection?
Both require variation, the presence of a selection pressure, and the heritability of the trait.
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What is a desirable trait in the context of selective breeding?
A heritable phenotype that humans select for during selective breeding.
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What is the key difference between selective breeding and natural selection?
The key difference lies in the origin of the selection pressure.
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How does selective breeding change a population's gene pool?
It alters the breeding behavior of animals and plants to develop a selected trait.
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What is the primary method of selective breeding?
To select for and breed individuals with a desirable trait together.
126
How can selective breeding affect genetic diversity?
It can lead to smaller gene pools and overexpression of deleterious alleles, reducing adaptability and fitness.
127
What can happen if poor breeding practices are implemented in selective breeding?
It can cause a human-induced genetic bottleneck.
128
What is a deleterious allele?
An allele that has an overall negative effect on individual fitness when expressed.
129
What is adaptive potential?
The ability for a population to adjust to new environmental selection pressures.
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What is a recessive allele?
A trait that can be masked by a dominant allele on a homologous chromosome.
131
How can selective breeding lead to increased inbreeding?
By restricting breeding to a small percentage of individuals expressing desired traits, leading to reduced genetic diversity.
132
What is an example of selecting against an unwanted trait?
Overfishing large-bodied fish to reduce their prevalence in the population.
133
What does it mean to be homozygous?
Having identical alleles for the same gene on homologous chromosomes.
134
How have humans historically altered the genomes of different species?
By expressing traits that we find desirable through inbreeding and heavy selection pressures.
135
What are the consequences of inbreeding and heavy selection pressures on genetic diversity?
They result in a large reduction in overall genetic diversity and species fitness, as well as the overexpression of previously repressed deleterious alleles.
136
What has led to the emergence of antibiotic-resistant bacteria?
The inappropriate use and overuse of antibiotics.
137
What is antimicrobial resistance?
The ability of a microorganism to survive exposure to an antimicrobial agent.
138
How does natural selection contribute to antibiotic resistance?
Exposure to antibiotics serves as an environmental selection pressure, favoring bacteria with resistance.
139
What is bacterial conjugation?
The process in which bacteria exchange genetic material via direct cell-cell contact.
140
What happens to bacteria that are susceptible to antibiotics?
They are killed by the antibiotic.
141
What role do antimicrobial agents play in medicine?
They protect us from harmful pathogens by killing or slowing their growth.
142
How does the allele frequency for antibiotic resistance change in a population?
It increases as resistant bacteria survive and replicate, while susceptible bacteria are killed.
143
What role do mutations play in the emergence of antibiotic resistance in bacteria?
Mutations facilitate the emergence of new alleles that help bacteria develop mechanisms to combat antibiotics, such as modified cell walls or active efflux of antibiotics.
144
What is a significant public health issue related to antibiotic-resistant bacteria?
The rapid emergence of antibiotic-resistant bacteria makes it difficult to treat infections, as existing antibiotics become ineffective.
145
How can inappropriate compliance with a treatment plan contribute to antibiotic resistance?
Prematurely stopping a course of antibiotics can allow pathogenic bacteria to replicate and accumulate mutations that confer resistance.
146
What is the impact of inappropriate use of antibiotics on antibiotic resistance?
Prescribing antibiotics for viral infections can expose normal flora to antibiotics, leading to the selection of antibiotic-resistant bacteria.
147
How does widespread use of antibiotics influence antibiotic resistance?
Increased use of antibiotics raises the probability of individuals being inhabited by antibiotic-resistant bacteria, allowing for their selection through natural selection.
148
What strategy do doctors often use to treat highly resistant strains of bacteria?
Doctors use combinations of different antibiotics with varying mechanisms of action to increase the chances of destroying the bacteria.
149
What is antigenic drift?
Antigenic drift involves small and gradual changes in the genes encoding for viral surface antigens, allowing the virus to evade recognition by memory cells.
150
What is antigenic shift?
Antigenic shift involves sudden and significant changes in the genes encoding for viral surface antigens, often occurring when different strains of a virus combine in a co-infected host.
151
How do antigenic drift and shift affect vaccine development?
Both processes increase the difficulty of developing effective, long-term vaccinations and medications against viruses due to the constant changes in viral surface antigens.
152
What is viral recombination?
Viral recombination is the combination of surface antigens from two or more different strains of a virus to form a completely new virus subtype.
153
What is the potential impact of antigenic shift on public health?
Antigenic shift can lead to the emergence of a new virus subtype that is highly infectious and may develop into an epidemic or pandemic.
154
What defines an epidemic?
An epidemic is defined as a dramatically increased occurrence of a disease in a particular community at a particular time.
155
What defines a pandemic?
A pandemic is an epidemic that has spread across multiple countries and/or continents.
156
What is antibiotic resistance?
Antibiotic resistance occurs when exposure to antibiotics serves as an environmental selection pressure and confers a selective advantage to bacteria with existing resistance.
157
How do viruses mutate?
Viruses can mutate via antigenic drift and shift, leading to the creation of new surface antigens.
158
Why are antibiotic resistance and viral mutations significant public health issues?
Both adaptations make it increasingly difficult to treat bacterial and viral infections.
159
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