bioa01 > 1-4 > Flashcards

1-4 Flashcards

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1
Q

What is phenotypic variation?

A

Differences in observable traits among individuals of the same species

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2
Q

How does human genetic variation compare to other species?

A

Humans rank low in genetic variation; only one DNA base per thousand differs on average

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3
Q

What is the average genetic difference between two randomly selected humans?

A

One DNA base per thousand

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4
Q

What are the two factors that contribute to phenotype?

A
  • Genotype
  • Environment
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5
Q

What is population genetics?

A

The study of patterns of genetic variation in natural populations

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6
Q

Define a species in the context of genetics.

A

A group of individuals capable of sharing alleles through reproduction

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7
Q

What is the gene pool?

A

All alleles present in all individuals of a species

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8
Q

What are the two sources of genetic variation?

A
  • Mutation
  • Recombination
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9
Q

What are somatic mutations?

A

Mutations that occur in nonreproductive cells and do not get passed to the next generation

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10
Q

What are germ-line mutations?

A

Mutations in reproductive cells that can be passed to the next generation

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11
Q

What is the significance of advantageous mutations?

A

They improve survival or reproduction chances and can increase in frequency in a population

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12
Q

What is allele frequency?

A

The proportion of a specific allele among all alleles of a gene in a population

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13
Q

What does it mean when a population is fixed for an allele?

A

Only one allele is present at a particular gene

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14
Q

What is genotype frequency?

A

The proportion of each genotype in a population

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15
Q

What is the ABO blood group?

A

A blood type determined by alleles A, B, and O of the ABO gene

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16
Q

How does protein gel electrophoresis help in population genetics?

A

It separates proteins to visualize genetic variation

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17
Q

What is the gold standard for measuring genetic variation?

A

DNA sequencing

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18
Q

What is a polymorphism?

A

A variable nucleotide position in a gene

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19
Q

What does evolution refer to at the genetic level?

A

A change in allele or genotype frequency over time

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20
Q

What does the Hardy-Weinberg equilibrium describe?

A

Situations in which allele and genotype frequencies do not change

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21
Q

True or False: Populations evolve, not individuals.

A

True

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22
Q

Fill in the blank: Mutations can be _______ or _______ based on their effects.

A

[deleterious] or [beneficial]

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23
Q

What is the role of recombination in genetic variation?

A

It creates new combinations of alleles during meiotic cell division

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24
Q

What constitutes evolution in terms of allele and genotype frequencies?

A

Any change in allele frequencies, genotype frequencies, or both constitutes evolution.

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25
What does the Hardy-Weinberg equilibrium describe?
Situations in which allele and genotype frequencies do not change.
26
What must occur for allele and genotype frequencies to change over time?
Specific forces must act on the population.
27
Who independently demonstrated the Hardy-Weinberg equilibrium in 1908?
G. H. Hardy and Wilhelm Weinberg.
28
What does the Hardy-Weinberg equilibrium indicate about evolutionary forces?
It indicates that evolution does not occur.
29
What are the conditions for a population to be in Hardy-Weinberg equilibrium? (List them)
* No difference in survival and reproductive success of individuals with different genotypes * Population is sufficiently large to prevent sampling errors * No migration into or out of the population * No mutation occurring * Individuals mate at random
30
What happens when there is a selective elimination of alleles?
The frequency of the eliminated allele will gradually decline.
31
What is genetic drift?
A change in the frequency of an allele due to the random effects of small population size.
32
What occurs when populations are added to or subtracted from by migration?
The frequency of alleles in the population can change.
33
What effect does mutation have on allele frequencies?
It can change allele frequencies if alleles mutate into different alleles.
34
What is the significance of random mating in the Hardy-Weinberg equilibrium?
Mate choice must be made without regard to genotype.
35
How do you calculate the expected genotype frequencies from allele frequencies under Hardy-Weinberg equilibrium?
Using the formulas: Frequency of AA = p², Frequency of Aa = 2pq, Frequency of aa = q².
36
If the frequency of allele A is p and allele a is q, what is the relationship between p and q?
p + q = 1.
37
What does the Hardy-Weinberg equilibrium provide for population genetic analysis?
A baseline from which to explore evolutionary processes.
38
What can be inferred if a population's allele or genotype frequencies are not in Hardy-Weinberg equilibrium?
Evolution has occurred in that population.
39
What is natural selection?
A mechanism that results in allele frequencies changing from generation to generation based on the allele's impact on survival and reproduction.
40
What is the impact of deleterious mutations on evolution?
They are eliminated by natural selection and have no long-term evolutionary impact.
41
How did Darwin contribute to the understanding of natural selection?
He suggested natural selection as a mechanism for adaptation and evolution.
42
What are the three key observations that form the basis of natural selection?
* Variation among individuals of a species * Some variation is heritable * Individuals with advantageous traits tend to survive and reproduce more than others
43
True or False: Natural selection can occur without variation among individuals.
False.
44
What is the first observation regarding variation among species?
Members of a species differ from one another, indicating variation among individuals of a species.
45
What does heritable variation mean?
Some variation is heritable, or passed on to the next generation.
46
Who pointed out the potential for natural populations to increase geometrically?
Thomas Robert Malthus.
47
According to Malthus, how can a population grow over generations?
Population can grow larger at an ever-increasing rate.
48
Why do population sizes typically remain stable?
Resources are limited, leading to competition for survival.
49
What did Darwin and Wallace suggest about individuals that are best adapted?
They are most likely to survive and leave more offspring.
50
What is the term Darwin used for the process that favors advantageous alleles?
Natural selection.
51
Define fitness in the context of evolutionary biology.
Fitness describes how well an individual survives and reproduces in a particular environment.
52
What is competitive advantage?
It is a function of how well an organism is adapted to its environment.
53
How does fitness relate to genotype representation in the next generation?
It measures the extent to which an individual's genotype is represented in the next generation.
54
Is fitness relative or absolute?
Fitness is relative and only makes sense in relation to other individuals of the same species.
55
What does natural selection do over generations to increase fitness?
It acts to increase the overall fitness of a population.
56
What is the Modern Synthesis in evolutionary biology?
It combines Mendelian genetics and Darwinian evolution.
57
What was a key missing component in Darwin's theory of evolution?
Mendel's genetic studies.
58
Who contributed to the synthesis of Darwin's theory and Mendelian genetics?
Ronald Fisher.
59
What does positive selection refer to?
Natural selection that increases the frequency of advantageous alleles.
60
What is negative selection?
Natural selection that reduces the frequency of deleterious alleles.
61
How can balancing selection maintain alleles in a population?
By acting to maintain two or more alleles at intermediate frequencies.
62
What is heterozygote advantage?
When the fitness of heterozygotes is higher than that of either homozygote.
63
In regions with malaria, which genotype has an advantage?
Heterozygous individuals (AS).
64
What are the three patterns of natural selection?
Stabilizing, directional, and disruptive selection.
65
What does stabilizing selection favor?
Intermediate phenotypes and acts against extremes.
66
Provide an example of directional selection.
Increased bill size in Galapagos finches after a drought.
67
What is an example of human-induced directional selection?
Bacteria evolving resistance to antibiotics.
68
Who won the Nobel Prize in Medicine or Physiology in 2015?
Tu Youyou
69
What is the active antimalarial component identified by Tu Youyou?
Artemisinin
70
What plant is artemisinin derived from?
Sweet wormwood (Artemisia annua)
71
What has emerged within a few years of deploying artemisinin against malaria?
Resistance
72
What type of selection pressure do medical interventions exert on pathogens?
Strong selection pressure
73
What happens to pathogen cells that have mutations conferring protection?
They survive and reproduce
74
What is disruptive selection?
Selection that favors extremes and acts against intermediate forms
75
What insect provides an example of disruptive selection in North America?
Apple maggot flies (Rhagoletis pomonella)
76
What did apple maggot flies originally feed on before the introduction of apples?
Hawthorn trees
77
How have apple trees influenced the life cycle of apple maggot flies?
They produce fruit earlier than hawthorns
78
What do biologists mean by the term selective pressure?
Environmental conditions that affect survival and reproduction
79
What can cause changes in selective pressures?
Environmental shifts
80
Is natural selection a forward-looking process?
No
81
What is artificial selection?
A form of directional selection where humans select for traits
82
What traits have farmers and breeders selected for in livestock and crops?
* Bitter kernels in corn * More milk in cows * Larger eggs in chickens * Faster running horses
83
What was the hypothesis of the corn experiment conducted at the University of Illinois?
There is a limit to the extent of population response to directional selection
84
What were the two lines of corn selected for in the experiment?
* High oil content * Low oil content
85
What was the result of selecting corn for high oil content?
Oil percentage quadrupled from about 5% to more than 20%
86
What happened to the line selected for low oil content?
Oil content fell close to zero
87
How many genes are indicated to affect the differences in oil content in selected corn lines?
At least 50 genes
88
How does artificial selection differ from natural selection?
It lacks the competitive element; successful phenotypes are selected by the breeder
89
What animal is cited as an example of efficient change generated by artificial selection?
Dogs
90
From what animal were dogs domesticated?
Wolves
91
Approximately how long ago were dogs domesticated?
Around 30,000 years ago
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