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Genetics > Chapter Fourteen: Chromosomal Rearrangements > Flashcards

Chapter Fourteen: Chromosomal Rearrangements Flashcards

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1
Q

two events that reshape genomes

A
  1. rearrangements
  2. changes in chromosome number
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2
Q

DNA sequences are reorganized within one or more chromosome

A

chromosomal rearrangement

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3
Q

loss or gain of entire chromosomes or sets of chromosomes

A

changes in chromosome number

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4
Q

karyotypes usually remain ___ within a species

A

constant

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5
Q

most genetic imbalances result in a ___

A

selective disadvantage

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6
Q

related species usually have ___ karyotypes

A

different

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7
Q

closely-related species differ by ___

A

a few rearrangements

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8
Q

distantly-related species differ by ___

A

many rearrangements

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9
Q

there is a correlation between karyotypic rearrangements and ___

A

speciation

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10
Q

four types of chromosomal rearrangements

A
  1. deletion
  2. duplication
  3. inversion
  4. reciprocal translocation
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11
Q

rearrangements that add or remove base pairs

A

deletion and duplication

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12
Q

rearrangements that relocate chromosomal regions without changing the number of base pairs

A

inversion and reciprocal translocation

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13
Q

___ and ___ can cause all four types of rearrangement

A

DNA breakage and aberrant crossing over

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14
Q

mistakes in rearranging antibody genes can lead to ___

A

cancer

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15
Q

___ can detect large chromosomal rearrangements

A

fluorescent in situ hybridization (FISH)

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16
Q

___ has probes specific for two different chromosomes to show chromosomal translocation

A

spectral karyotyping (SKY)

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17
Q

___ is produced by using FISH probes for particular regions of chromosomes

A

multicolor banding

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18
Q

what is the ultimate way to determine if any chromosomal rearrangements are present

A

sequencing

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19
Q

in an organism with a deletion, ___ reads would be detected in that section; in an organism with a duplication, ___ reads would be detected in that section

A

fewer
more

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20
Q

whole genome sequencing can detect all rearrangements because ___

A

it will point out sequences that are not normally next to each other

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21
Q

the precise base pairs at which rearranged chromosome segments begin and end

A

rearrangement breakpoints

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22
Q

rearrangement breakpoints can be identified by ___

A

PCR and sequencing

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23
Q

PCR analysis for rearrangement breakpoints is ___ and ___

A

inexpensive and sensitive

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24
Q

deletion on both chromosomes

A

deletion homozygosity

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25
Q

homozygosity for deletions is often ___ or ___

A

lethal or harmful

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26
Q

the effect of a homozygous deletion depends on ___ and ___

A

size of deletion and affected genes

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27
Q

deletion on one chromosome

A

deletion heterozygosity

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28
Q

deletion heterozygotes can have a mutant phenotype due to ___

A

gene dosage effects (haploinsufficiency)

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29
Q

what is haploinsufficiency

A

only one functional gene does not produce enough protein for the normal phenotype

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30
Q

in deletion heterozygotes cells become vulnerable to ___ that will impact the ___

A

mutations
remaining normal chromosome

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31
Q

if a deletion heterozygote carries a recessive allele on the normal chromosome, the organism will display the ___ phenotype

A

recessive mutant

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32
Q

deletions can be used to locate ___

A

genes

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33
Q

examining the phenotype of a deletion heterozygote can tell you ___

A

where a specific gene is

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34
Q

if the phenotype of the gene is mutant, you know the gene must lie ___ the deleted region; if the phenotype is wild-type, you know the gene must lie ___ the deleted region

A

inside
outside

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35
Q

edits genes by precisely cutting DNA and then letting natural DNA repair take over

A

CRISPR

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36
Q

___ form in the chromosomes of deletion heterozygotes

A

deletion loops

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37
Q

recombination between homologs can occur only at regions of ___

A

similarity

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38
Q

no ___ can occur within a deletion loop

A

recombination

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39
Q

because of deletion loops, ___ will not be accurate

A

genetic map distances

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40
Q

why do deletion loops form in deletion heterozygotes

A

genes on the normal homolog don’t have a sequence to match up with on the chromosome with the deletion

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41
Q

most duplications have ___ phenotypic consequences

A

no

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42
Q

why do most duplications produce normal phenotypes

A

increased gene copy number or altered expression in new chromosomal environment

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43
Q

homozygosity or heterozygosity for a duplication can be ___ or ___ depending on ___ and ___

A

lethal or harmful
size of duplication and affected genes

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44
Q

unequal crossing over between duplicated regions on homologous chromosomes can result in ___ and ___ copy number

A

increased and decreased

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45
Q

repeats of a chromosomal region that lie next to each other, either in the same order or reverse order

A

tandem duplications

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46
Q

repeats of a chromosomal region that are not next to each other

A

nonrandom duplications

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47
Q

nonrandom duplications can be on the ___ or ___ from the original copy

A

same chromosome or a different chromosome

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48
Q

with some genes, an abnormal phenotype can be caused by an imbalance in ___

A

gene dosage

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49
Q

the ___ gene in drosophila is extremely dosage sensitive

A

notch+

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50
Q

haploinsufficient and duplication heterozygotes for the notch+ gene have a ___

A

mutant phenotype

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51
Q

in unequal crossing over, one chromosome ends up with a ___ and the other ends up with a ___

A

duplication
deletion

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52
Q

most inversions result in ___

A

normal phenotype

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53
Q

two reasons inversions can result in an abnormal phenotype

A
  1. inversion disrupts a gene
  2. inversion takes place near regulatory sequences for other genes or near heterochromatin
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54
Q

inversions can act as crossover ___

A

suppressors

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55
Q

in inversion heterozygotes, no viable offspring are produced that carry chromosomes resulting from ___

A

recombination int he inverted region

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56
Q

___ can produce inversions

A

chromosome breakage

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57
Q

inversion in which the centromere is within the inverted segment

A

pericentric inversion

58
Q

inversion in which the centromere is not within the inverted segment

A

paracentric inversion

59
Q

___ form in inversion heterozygotes

A

inversion loops

60
Q

in an inversion loop, one chromosomal region rotates to conform to the ___

A

sequence of its homolog

61
Q

formation of inversion loops in meiosis allows the ___ of homologous regions

A

tightest possible alignment

62
Q

crossing over within the inversion loop produces ___

A

aberrant recombination chromatids

63
Q

paracentric and pericentric inversion heterozygotes both result in ___

A

reduced fertility

64
Q

in pericentric inversion heterozygotes, each recombinant chromatid ___, but each will be ___

A

has a centromere
genetically imbalanced

65
Q

zygotes formed from normal chromosomes with chromosomes with these recombinant chromatids will be ___

A

nonviable

66
Q

in paracentric inversion hetrozygotes, one chromosome ___ and the other ___

A

lacks a centromere
has two centromeres

67
Q

zygotes formed from normal chromosomes with chromosomes with these dicentric recombinant chromatids will be ___

A

nonviable

68
Q

which is worse: pericentric or paracentric inversion

A

paracentric

69
Q

inversions act as crossover ___

A

suppressors

70
Q

only gametes that did not recombine with inversion loop are ___

A

viable

71
Q

crossover suppression is used to make ___

A

balancer chromosomes

72
Q

balancer chromosomes are used for ___

A

genetic analysis

73
Q

balancer chromosomes have ___, ___ inversions

A

multiple, overlapping

74
Q

in balancer heterozygotes, no viable recombinant progeny will be produced because of ___

A

crossover suppression

75
Q

attach part of one chromosome to a non homologous chromosome

A

translocation

76
Q

parts of two nonhomologous chromosomes switch places

A

reciprocal translocation

77
Q

reciprocal translocations result in ___ of genetic material

A

no loss

78
Q

reciprocal translocations usually result in ___ phenotype

A

normal

79
Q

reciprocal translocations may result in mutant phenotype if breakpoint is ___

A

within or near a gene

80
Q

reciprocal translocations may result in decreased ___

A

fertility

81
Q

a reciprocal translocation is the genetic basis for chronic ___

A

myelogenous leukemia

82
Q

leukemia patients have too many ___

A

white blood cells

83
Q

in a translocation homozygote, chromosomes segregate ___ during meiosis I

A

normally

84
Q

is the breakpoints of a reciprocal translocation do not affect gene function, there are no ___ in homozygotes

A

genetic consequences

85
Q

in a translocation heterozygote, the two haploid sets of chromosomes carry ___ arrangements of DNA

A

different

86
Q

chromosome pairing during prophase I of meiosis is maximized by formation of a ___

A

cruciform structure

87
Q

three chromosome segregation patterns are possible for translocation heterozygotes

A
  1. alternate
  2. adjacent-1
  3. adjacent-2
88
Q

balanced gametes are produced only by ___ segregation

A

alternate

89
Q

in reciprocal translocation heterozygote, only the ___ segregation pattern results in viable progeny

A

alternate

90
Q

___ is observed in heterozygotes with reciprocal translocation

A

pseudolinkage

91
Q

translocation arising from breaks at or near the centromeres of two acrocentric chromosomes

A

robertsonian translocation

92
Q

in robertsonian translocations, the small chromosome may be ___

A

lost from the organism

93
Q

___ can arise from a robertsonian translocation between chromosomes 21 and 14

A

down syndrome

94
Q

any segment of DNA that evolves the ability to move from place to place within a genome

A

transposable elements (TE)

95
Q

Marcus Rhoades and Barbara McClintock inferred existence of TEs from genetic studies of ___

A

corn

96
Q

TEs have been found in ___

A

all organisms

97
Q

TEs were previously considered to be selfish DNA because they ___

A

carried no genetic information useful to the host

98
Q

it is now know that some TEs have evolved ___

A

functions beneficial to the host

99
Q

TE length ranges from ___ to ___

A

50bp to 10kb

100
Q

TEs can be present in ___copies per genome

A

hundreds of thousands

101
Q

discoverer of TEs

A

Barbara McClintock

102
Q

molting of corn kernels is caused by ___

A

movements of a TE into and out of pigment gene

103
Q

two types of TEs

A
  1. retrotransposons
  2. DNA transposons
104
Q

three types of retrotransposons

A
  1. long interspersed elements (LINEs)
  2. short interspersed elements (SINEs)
  3. human endogenous retroviruses (HERVs)
105
Q

LINEs and SINEs have ___

A

poly-A tails

106
Q

HERVs have ___

A

long terminal repeats

107
Q

HERVs are similar in structure to ___

A

retroviruses

108
Q

retrotransposons move via ___

A

RNA intermediates

109
Q

LINEs and HERVs have a gene encoding ___

A

reverse transcriptase

110
Q

the reverse transcriptase gene is a clue that LINEs and HERVs ___

A

move via an RNA intermediate

111
Q

retrotransposons move via ___

A

RNA intermediates

112
Q

experiment done with ___ proved that retrotransposons move via RNA intermediates

A

Ty1 retrotransposon of yeast

113
Q

Ty1 with an intron was cloned into a ___

A

plasmid

114
Q

all new insertions of the Ty1 into the genome ___

A

lacked the intron

115
Q

the intron must have been removed by ___

A

splicing from an RNA

116
Q

five steps of how an LTR retrotransposon moves

A
  1. transcription of retrotransposons
  2. synthesis of cDNA by reverse transcriptase
  3. staggered cut made in genomic target site
  4. retrotransposon cDNA inserts into target site
  5. original copy remains while new copy inserts into another genomic location
117
Q

TEs whose movement does not rely on an RNA intermediate

A

transposon

118
Q

most DNA transposons contain ___ and ___

A

inverted repeats of 10-200bp long at each end and a gene encoding transposase

119
Q

recognizes inverted repeats (IRs) and cuts at the border between the IR and genomic DNA

A

transposase

120
Q

transposase catalyzes the movement of ___

A

DNA transposons

121
Q

genes often contain ___ copies of TEs

A

defective

122
Q

many TEs sustain ___ during the process of transpositions or after transposition

A

deletions

123
Q

if a deletion removes the promoter for retrotransposon transcription, ___

A

it cannot generate the RNA intermediate for future movements

124
Q

if the deletion removes one of the inverted repeats at the end of a transposon, ___

A

transposase will be unable to catalyze transcription

125
Q

deletions can create ___ TEs that cannot ___

A

defective
transpose again

126
Q

non-deleted TEs that can transpose on their own

A

autonomous TEs

127
Q

defective TEs that require the activity of non-deleted copies for the TE for movement

A

nonautonomous TEs

128
Q

TEs can disrupt ___ and alter ___

A

genes
genomes

129
Q

TE insertion can result in an altered phenotype if ___ or ___

A

it is inserted within the coding region of a gene or if is inserted near a gene

130
Q

TE associated alleles can be ___

A

unstable

131
Q

TEs can trigger spontaneous ___

A

chromosomal rearrangements

132
Q

there can be ___ between two copies of the same TE pair

A

unequal crossing over

133
Q

transposition can cause gene ___

A

relocation

134
Q

mutations in eye color of drosophila because of TE insertions depend on ___ and ___

A

which TE is inserted and where it is inserted

135
Q

gene relocation due to transposition can occur when two copies of a TE integrate in ___

A

nearby locations on the same chromosome

136
Q

alternative splicing of transposase gene limits ___

A

TE movement

137
Q

one splice produces ___, another splice produces ___; these two compete to ___

A

transposase
repressor of transposition
bind to the inverted repeats

138
Q

chromosome rearrangements are sources of ___

A

variation

139
Q

genes at or near rearrangement breakpoints may have new ___ or be ___

A

patterns of expression
fused with another gene

140
Q

transposable elements can alter ___ or ___

A

patterns of expression or inactivate a gene

141
Q

sets of related genes with slightly different functions

A

gene families

142
Q

gene families most likely arose from ___

A

gene duplications

Genetics (24 decks)

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