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Bisc 160 > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

if big feet (B) in schmoos is dominant to small feet (b), the genotype of a big-footed schmoo with respect to the foot gene can

A

either be Bb or BB.

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2
Q

The ultimate origin of genetic variation is

A

mutation

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3
Q

A mutation to a gene that results in a protein being expressed that is capable of working in a different way than before is categorized as:

A

gain of function

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4
Q

A cell in G2 contains 36 sister chromatids. This same cell in G1 would have

A

18 chromosomes.

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5
Q

If a cell has 20 chromosomes in G2, after S phase it will have

A

20 chromosomes

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6
Q

A mutation of the underlined G of following sequence 3’ -TACTGGGTAACA-5’ to a T would be a:

A

silent mutation

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7
Q

Humans have _______ pairs of autosomes.

A

22

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8
Q

A haploid cell is a cell

A

containing only one copy of each chromosome.

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9
Q

The number of daughter chromosomes in a human cell (diploid number 46) in anaphase II of meiosis is

A

46

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10
Q

An allele in a population of oysters has a frequency of 0.21. Out of 600 oysters, _______ copies of the allele are present.

A

252

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11
Q

Which statement about the theories of blending inheritance and particulate inheritance is correct?

A

Genes remain stable across generations according to the theory of particulate inheritance, but not according to blending inheritance.

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12
Q

The height of the plant is called its

A

phenotype

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13
Q

In an organism in which the diploid number is 10, _______ different types of gametes can be produced by independent assortment alone.

A

32

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14
Q

A population of monkeyflowers has 39 individuals that are BB at a locus, 42 that are Bb, and 19 that are bb. This population has _______ heterozygotes than would be expected under Hardy-Weinberg equilibrium.

A

6 fewer

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15
Q

In a population of field mice in the Sand Hills of Nebraska, some individuals have lighter coat colors than others. Which of the following would be the most efficient way of determining whether the lighter coat color is a heritable trait?

A

Breeding the mice of both colors in the lab and observing the coat colors of their offspring

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16
Q

A human male carrying an allele for a trait on the X chromosome is

A

hemizygous

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17
Q

What statement best describes why the process of meiosis is important to Mendel’ s law of independent assortment of traits on different chromosomes?

A

In meiosis, how each pair of homologous chromosomes segregates is unaffected by what other pairs do.

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18
Q

If two strains of true-breeding plants that have different alleles for a certain character are crossed, their progeny are called

A

F1

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19
Q

The parents of individuals in the F2 generation are members of the _______ generation.

A

F1

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20
Q

Hyenas have 40 chromosomes before DNA replication. At the end of metaphase in mitosis, hyenas have ______ chromosomes and just before telophase, they have ______ chromosomes.

A

40; 80

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21
Q

Sexual reproduction increases genetic variability through

A

crossing over, independent assortment, and random fertilization.

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22
Q

Genetic variation is the raw material of evolution. Which of the following is the primary source of genetic variation within animal populations?

A

mutation

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23
Q

A mechanism for increasing the genetic diversity of offspring is

A

sexual reproduction.

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24
Q

Accidents that can occur during meiosis and result in trisomies and monosomies are called

A

nondisjunctions.

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25
If there are only two alleles at a given locus and the frequency of one allele is 0.6, what is the frequency of the other allele?
0.4
26
In a human female when an egg is ovulated, it is arrested in metaphase of meiosis II and does not complete meiosis II unless fertilization takes place . Therefore, after ovulation and prior to fertilization, this egg contains _______ chromosomes and _______ chromatids.
23; 46
27
In cocker spaniel dogs, black color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s). If the genes are unlinked and the offspring of BBss and bbss individuals are mated with each other, what fraction of their offspring will be black and spotted?
16/16
28
Cleft chin is an X-linked dominant trait. Assume that a man with a cleft chin marries a woman with a round chin. What percent of their female progeny will show the cleft chin trait?
100%
29
By definition, ___ could never occur without genetic change within a population.
evolution
30
In order to determine the genotype of an individual displaying a dominant trait, you cross it with an organism that displays the recessive trait. This is called a(n)
test cross
31
In a species of beetles, some individual beetles have horns, whereas others do not, and a single gene is responsible. Individuals that are hh lack horns, individuals that are Hh have horns, and individuals that are HH die as embryos. Two horned individuals mate. Of their 600 surviving offspring, _______ should have horns.
400
32
In order for a population to evolve,
its members must have heritable genetic variation
33
Curly wing is recessive to straight wing in Drosophila. In a cross between true-breeding curly- and straight-winged parental flies, there are 480 flies in the F2 generation. How many F2 progeny should have curly wings?
120
34
Several populations of copepods are sampled for variation at the G locus. Population A is found to be 30 percent GG, 60 percent Gg, and 10 percent gg. Population B is 62 percent GG, 36 percent Gg, and 2 percent gg. Population C is 30 percent GG, 40 percent Gg, and 30 percent gg. Which population or populations shows a heterozygote deficiency?
Population C
35
One of the major contributions of Mendel to the study of genetics was
the use of probability to analyze data.
36
In humans, red-green color blindness is determined by an X-linked recessive allele (a), whereas eye color is determined by an autosomal gene, where brown (B) is dominant over blue (b). What gametes can be formed with respect to these genes by a heterozygous, brown-eyed, color-blind male?
BXa, BY, bXa, bY
37
A(n) _______ cross involves two different genes, each affecting a different character.
dihybrid
38
if white-eyed flies are crossed with other white-eyed flies from the same strain, the offspring will all have white eyes. This trait can thus be said to be
true-breeding
39
what is a point mutation?
addition or subtraction of a single base pair or substitution of one for another
40
what are the two types of substitutions for point mutation?
transition (purine for purine or pyrimidine for pyrimidine) and transversion (purine replaces pyrimidine or pyrimidine replaces purine)
41
what are the different types of mutations for DNA substitutions?
Silent mutations: DNA subs that change sense codon into another sense that codes same amino acid Missense: DNA subs that change sense to another sense that codes different amino acid Nonsense: change sense to stop codon Loss of stop: change stop to sense codon
42
what mutation happens when you add or delete a base pair?
Frameshift mutation where DNA base pair is inserted/deleted into sequence which leads to a "shift" in reading
43
what are the different types of chromosomal mutations?
deletion: removal of parts of genetic material duplication: can happen at same time as deletion & happen when homologous chromosomes break @ different positions and reconnect with wrong partner (one ends up w/ deleted segment and one has duplicated) inversion: results from breaking and flipped rejoining translocation: when segment of chromosome break & reattach to different one (one for Down syndrome)
44
what are the different types of life-cycles?
haplontic: mature organism is haploid & only zygote diploid haplo-diplontic: passes through haploid & diploid stages that are multicellular diplontic: organism is diploid & gametes are haploid
45
what are homologous pairs?
identical in size and appearance but they (homologs) are genetically different (alleles)
46
what are the 3 main effects of meiosis?
1. ensures each haploid has complete set of chromosomes 2. reduces from 2N to N (nucleus divides twice but replication happens once) 3. chromatid exchange during meiosis I generate genetic diversity * unique to meiosis I: homologous come together to pair and separate
47
how do chromatids exchange genetic material?
homologous replicated chromosomes pair by adhering along length by synapsis (synapsis pair called bivalent). they begin to be pulled apart but held together by cohesions & regions have x-shaped called chiasmata (where crossing over happens, resulting in recombinant chromosome)
48
what is nondisjunction?
homologous chromosomes fail to separate, sister chromatid fail to separate, or homologous fail to remain together during metaphase I but migrate to same pole in anaphase I (result in trisomies or monosomes)
49
what are the two theories of genetics?
blending inheritance: gametes contained hereditary determinants that blended when fused particulate inheritance: determinants had physically distinct nature & remain intact when fused
50
what is the difference between character, trait, and phenotype?
character: observable physical feature (seed shape) trait: particular form of character (round/wrinkled seed) phenotype: one/more character is observable properties of individual from genetic & environmental factors
51
what did Mendel find out about hereditary determinants?
they are not particulate but physically distinct entities (sequences of DNA carried on chromosomes called genes)
52
what is the law of segregation?
when any individual produces gametes, 2 copies of gametes separate so half of gametes receive one copy & other half receive other copy (Anaphase I)
53
what is the law of independent assortment?
alleles of different genes assort independently from one another
54
what does a test cross do?
determines whether individual with dominant trait is homozygous or heterozygous *punnet square calculates all possible combinations of gametes
55
how is probability of events found?
two independent events occurring together by multiplication (and) either of two independent events occurring by addition (or)
56
what is a wild type allele?
one present in most individual in wild (gene that has wild allele <99% of time is polymorphic)
57
what are the different types of dominance?
simple dominance incomplete dominance: when neither of 2 alleles is dominant & offspring is intermediate codominance: 2 alleles produce 2 different phenotypes that both appear
58
what is pleiotropic?
single allele influence more than one phenotype (PKU disease influence hair, skin, etc)
59
what is epistatsis?
when phenotypic expression of one gene is affected by another (lab color) - b/c E allele is needed for expression of B & b alleles, E is epistatic to B (lab with BBee will be yellow because e determines if the color is expressed)
60
how does genotype and environment interact to produce phenotype?
penetrance: proportion of individual in group with genotype to show expected phenotype expressivity: degree to which genotype is expressed in individual
61
what is the difference between qualitative and quantitative?
qualitative: descriptive info (small variation) while quantitative has continuous variation (b/c of gene and environment)
62
what is a chromosomal region that determines complex characters called?
quantitative trait loci - locus is specific position on chromosome
63
what is evolution?
change in genetic composition of populations over time (frequency of different alleles) - was, can be, and is observable & quantifiable
64
what are the 3 aspects of Charles Darwin theory?
1. species are not immutable; they change over time 2. divergent species share common ancestor (descent with modification) 3. changes in species explained by natural selection
65
what is selective breeding also called?
artificial selection
66
what is a population?
group of individuals of same species that live & interbreed in one area *individuals do not evolve, populations do
67
natural selection acts with what to cause evolution?
mutation, gene flow, genetic drift, and nonrandom mating
68
what are the two types of mutations?
deleterious (harmful) or have no effect (neutral)
69
what is allele frequency?
proportion of each allele in gene pool (sum of genetic variation in population)
70
what is adaptation?
favored trait spreads through population through natural selection (Moth's wing tail)
71
what is genetic drift?
random changes in allele frequencies from one generation to another (cause large changes in small populations)
72
what is population bottleneck?
large populations pass through event that only few survive (2 alleles called drift) *can also apply to pioneering species in founder effect
73
what does nonrandom mating produce?
changes in genotype frequencies but not allele frequencies
74
what is sexual selection?
individuals preferably mate w/ particular individual (phenotype not survival but reproduction chances)
75
what does Hardy-Weinberg equilibrium need in order to be true?
no mutation, no selection among genotypes, no gene flow, population size is infinite, and mating is random
76
what does natural selection act on?
acts directly on phenotype and indirectly with genotype
77
what is fitness?
reproductive contribution of phenotype to subsequent generations relative to other phenotypes *determined by relative rates of survival & reproduction of individual w/ that phenotype
78
what is stabilizing selection?
preserves average characteristics of population by favoring average individuals (reduces variation but not change mean)
79
what is directional selection?
changes characteristics by favoring individuals that varying one direction from mean
80
what is disruptive selection?
changes characteristics of population by favoring that vary in both directions from mean
81
what does natural selection must have?
1. occur when individuals differ in ability to survive/reproduce 2. birth & death rates occur at high rates 3. phenotypic traits improve survival/reproduction 4. traits heritable (amount of phenotypic variation in trait due to genetic variability) 5. variation in heritable trait 6. specific to environment 7. selection pressure from predators 8. change in phenotype/genotype frequency
82
what are the 3 species concept?
1. morphological concept 2. reproductive isolation 3. lineage species concept
83
what is morphological concept?
construct assuming species comprise of individuals that look alike & individuals that do not look alike belong to different species
84
what is reproductive isolation?
state in which 2 groups of organisms can no longer exchange genes
85
what is lineage species concept?
think of species as branches on tree of life
86
what is the Dobzhansky-Muller modal?
when previously same species are geographically isolated from each other, they become 2 distinct species & come together again, may have chance to interbreed but may be lethal/inferior

Bisc 160 (8 decks)

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