Deck 13: Chromosome Aberrations and Transposition

Question 1

A chromosome contains the following gene order: A B C D • E F G H
Which of the following rearrangements represents a pericentric inversion?

A)A B C • D E F G H
B)A F G H • B C D E
C)A C B D • E F G H
D)A F D E • C B G H
E)A B C D • H G F E

Answer 1

D

Question 2

AluI is an example of which type of transposable element commonly found in the genome of humans?

A)LINE elements
B)SINE elements
C)P elements
D)Copia elements
E)Ty elements

Answer 2

B

Question 3

When nondisjunction occurs early in embryogenesis rather than gametogenesis,what would you expect in the resulting karyotype?

A)monosomy
B)trisomy
C)mosaicism
D)uniparental disomy
E)random X-inactivation

Answer 3

C

Question 4

In bacteria,what is contained within the IS elements?

A)transposase gene
B)short tandem repeats
C)inverted repeats
D)Both A and B are correct.
E)Both A and C are correct.

Question 5

Which type of chromosome deletions is caused by two concurrent chromosome breaks (rather than a single break)?

A)acentric deletions
B)microdeletions
C)terminal deletions
D)partial deletions
E)interstitial deletions

Question 6

Prader-Willi and Angelman syndromes are caused by which type of chromosomal mutations,both in connection with chromosome 15?

A)monosomy
B)trisomy
C)mosaicism
D)uniparental disomy
E)random X-inactivation

Question 7

Humans with the condition of familial Down syndrome exhibit which type of chromosomal aberration?

A)chromosome 21 duplication
B)chromosome 21 inversion
C)chromosome 14/21 Robertsonian translocation
D)chromosome 21 deletion
E)trisomy of chromosome 21

Question 8

Which type of chromosome breakage results in very small deletions that are too small to identify on a karyotype?

A)acentric deletions
B)microdeletions
C)terminal deletions
D)partial deletions
E)interstitial deletions

Question 9

Crossover suppression implies that

A)there are no crossovers between homologous chromosomes.
B)recombinant chromosomes are absent in the progeny.
C)small inversions have a high frequency of crossover.
D)nonreciprocal translocations prevent equal exchange of chromosomes,resulting in loss of chromosome fragments.
E)Both A and C are correct.

Question 10

What sequences or structures within the DNA can be used to identify sites of transposition?

A)target site duplication and direct repeats
B)target site duplication and short tandem repeats
C)inverted loops
D)target site inversion and direct repeats
E)chromosome translocation and insertion of transposase gene

Question 11

A chromosome has broken,and a piece of one chromosome is translocated to a nonhomologous chromosome.This is an example of what type of chromosomal alteration?

A)paracentric inversion
B)dicentric bridge
C)unbalanced translocation
D)Robertsonian translocation
E)inversion loop

Question 12

In an allopolyploid organism,what is true regarding the fertility of interspecies hybrids?

A)Interspecies hybrids are fertile due to nonhomology of chromosomes.
B)Chromosome doubling and nondisjunction in gametocytes can lead to homologous chromosome pairing,disjunction,and fertile hybrids.
C)Interspecies hybrids will be fertile so long as there is an even number of chromosomes in the offspring.
D)Mitotic nondisjunction results in haploid cells.
E)Meiotic nondisjunction produces three haploid gametes and one diploid gamete.

Question 13

What type of aneuploidy is responsible for Turner syndrome in humans?

A)trisomy 13
B)trisomy 18
C)trisomy 21
D)monosomy XO
E)monosomy YO

Question 14

If a plant is an autotetraploid with the genotype A₁A₁A₂A₂,what is the frequency of offspring with the genotype A₁A₁A₁A₁ following self-fertilization of the plant?

A)1/2
B)1/4
C)9/16
D)8/36
E)1/36

Question 15

An organism with a genome size of n = 23 experienced a Robertsonian translocation.How many chromosomes would you expect to see in the karyotype of a somatic cell in an affected individual?

A)21
B)25
C)42
D)44
E)46

Question 16

A chromosome contains the following gene order: A B C D • E F G H
Which of the following rearrangements represents a paracentric inversion?

A)A B C • D E F G H
B)A F G H • B C D E
C)A C B D • E F G H
D)A F D E • C B G H
E)A B C D • H G F E

Question 17

If an organism is an inversion heterozygote,

A)homologous chromosomes align during meiosis through formation of an inversion loop at synapsis.
B)homologous chromosomes align during meiosis through formation of a Holliday junction at synapsis.
C)nonhomologous chromosomes pair during meiosis due to the translocation of genes between two different chromosomes.
D)it will experience normal chromosome synapsis during meiosis.
E)it will be unable to complete replication due to DNA damage,and the cell cycle will be arrested.

Question 18

In balanced translocation heterozygotes,which pattern of chromosome segregation produces viable gamets and progeny?

A)adjacent-1 segregation
B)adjacent-2 segregation
C)alternate segregation
D)Adjacent-1 and alternate segregation are both viable.
E)Adjacent-1,adjacent-2,and alternate segregation are all viable.

Question 19

Heterozygous carriers of chromosome inversions or translocations

A)will be viable and completely fertile because no genes were deleted.
B)may or may not exhibit phenotypic abnormalities.
C)may be infertile due to complications during meiosis.
D)Both A and B are correct.
E)Both B and C are correct.

Question 20

A region of a chromosome on spanning the centromere is broken and reattached in the reverse direction.This is an example of which type of chromosomal defect?

A)paracentric inversion
B)pericentric inversion
C)pericentric translocation
D)dicentric inversion
E)dicentric translocation

Question 21

Of the various genetic elements described by McClintock,which one is classified as an autonomous transposable element?

Question 22

What is the name of the chromosomal region,located on region 21q22.2 that was identified by studying individuals with partial trisomy of chromosome 21?

Question 23

In Drosophila and Lepidoptera,sex-chromosome mosaicism produces what type of sexually ambiguous phenotype?

Question 24

A partial chromosome deletion or duplication can be observed at prophase I homologous chromosome synapsis during meiosis by looking for what structure?

Question 25

Which enzyme(s)is/are responsible for excising and copying transposable genetic elements from chromosomes and inserting them into new locations?

Question 26

What two features are consistently seen within retrotransposons?

Question 27

Barbara McClintock identified corn mutants with the unstable mutant phenotype with what pattern of color?

Question 28

Pseudodominance is used to map genes by using what method?

Question 29

During gametogenesis,what percentage of gametes would be trisomic if the nondisjunction event occurs during meiosis II?

Question 30

What are the two common patterns of chromosome segregation seen in the tetravalent structures found in translocation heterozygotes?

Question 31

In McClintock's maize studies,which genetic element is found at the site of chromosome breakage?

Question 32

What structure,seen during synapsis,is indicative of a chromosome inversion?

Question 33

During gametogenesis,what percentage of gametes would be aneuploid if the nondisjunction event occurs during meiosis I?

Question 34

Gametes produced by inversion heterozygotes can produce no viable recombinant chromosomes due to what phenomenon?

Question 35

Cri-du-chat syndrome is a human disorder caused by which type of chromosomal defect?

Question 36

What effect does a Robertsonian translocation have on chromosome number?

Question 37

P elements cause which phenomenon responsible for sterility in Drosophila?

Question 38

"Seedless" fruits and vegetables have how many chromosomes and what type of chromosomal distribution?

Question 39

How many possible genotypes will there be following self-fertilization of a plant with the B₁B₁B₂B₂B₃B₃ genotype?

Question 40

Of the three mechanisms leading to autopolyploidy,which is the most rare event?

Question 41

Provide a description of the cellular mechanisms by which one reciprocal cross leads to hybrid dysgenesis while the other does not.

Question 42

Compare and contrast the two types of transposable elements found in bacteria.Provide examples of how transposable elements can be both harmful and beneficial to bacteria.

Question 43

What does the model of hybrid dysgenesis predict for the F₁ and F₂ generations when an M-cytotype male is crossed to a P-cytotype female?

Question 44

The phenomenon of ________ in allopolyploids consists of more rapid growth,increased fruit and flower production,and improved disease resistance.

Question 45

McClintock's transposable genetic element hypothesis was that the unstable mutant phenotype resulted when a ________ created a mutation by its insertion into the ________ allele and led to reversion when the expression of ________ led to its removal.

Question 46

How is aneuploidy different from polyploidy? What are the mechanisms by which aneuploidy and polyploidy are caused,and what are the consequences of these chromosomal alterations in terms of survival and fertility of the offspring?

Question 47

How are retroviruses and retrotransposons similar? Describe the genes encodes by the DNA of the retrovirus and the two DNA elements consistently found in retrotransposons.

Question 48

________ is rare and occurs most commonly when repetitive regions of homologous chromosomes misalign,resulting in partial deletions and partial duplications.

Question 49

What does the model of hybrid dysgenesis predict for the F₁ and F₂ generations when a P-cytotype male is crossed to an M-cytotype female?

Question 50

________ is a genetic phenomenon that occurs when a normally recessive allele is "unmasked" and expressed in the phenotype because the dominant allele on the homologous chromosome has been deleted.

Question 51

Chromosomal translocation involves chromosome breakage and reattachment of the broken segment to a ________.

Question 52

How might L1 retrotransposons be useful as a potential gene therapy agent? What are the problems with using this strategy for gene therapy?

Question 53

If you wish to target a retrovirus in a cell but do not want to disrupt retrotransposons,which gene(s)would you target?

Question 54

Describe two mechanisms for causing uniparental disomy,and explain how this chromosomal defect is involved in Prader-Willi syndrome and Angelman syndrome.