Deck 10: Chromosome Chapter Title Tbd

Question 1

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

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

Answer 1

D

Question 2

A karyotype shows that a child has Klinefelter syndrome (47,XXY). If the child is also color- blind (due to a recessive X- linked allele), despite his parents having normal color vision, in which parent and stage of meiosis did nondisjunction occur?

A) father in meiosis I
B) mother in meiosis I or II
C) mother in meiosis II
D) father in meiosis II
E) mother in meiosis I

Answer 2

C

Question 3

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

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

Answer 3

C

Question 4

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

A) acentric deletion
B) partial deletion
C) terminal deletion
D) interstitial deletion
E) microdeletion

Question 5

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

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

Question 6

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

Question 7

Which type of chromosome has no p arms?

A) acrocentric
B) telocentric
C) metacentric
D) submetacentric
E) subacrocentric

Question 8

Species A has 2n=16 chromosomes and species B has 2n=14 chromosomes. Offspring that are diploid for either 22 or 23 chromosomes are most likely?

A) allohexaploids
B) allotriploids
C) autotetraploids of species B
D) autotriploids of species A
E) allotetraploids

Question 9

Which of the following is true of the gametes of a human female who has nondisjunction of her X chromosomes in meiosis I?

A) The gametes contain 22 or 24 chromosomes.
B) The gametes contain 22, 23, or 24 chromosomes.
C) All the gametes contain 22 chromosomes.
D) All the gametes contain 23 chromosomes.
E) All the gametes contain 24 chromosomes.

Question 10

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

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

Question 11

Which of the following is FALSE of Down syndrome?

A) There are homologs in model organisms, such as mice and Drosophila, for genes in the Down syndrome critical region (DSCR).
B) Studying individuals with partial trisomy of chromosome 21 identified the Down syndrome critical region (DSCR) with a small number of genes responsible for the principal symptoms.
C) Down syndrome is the most common triploidy (3n) in which individuals have three sets of chromosomes.
D) Molecular genetic analysis of the chromosomes in infants with trisomy 21 determined that the majority of cases were attributable to maternal nondisjunction in meiosis I.
E) There is a link between the increased risk of Down syndrome and increased maternal age at conception.

Question 12

Which of the following is FALSE regarding organization in an interphase nucleus?

A) Each chromosome is localized to a specific region of the nucleus.
B) Each chromosome may assume a position that allows for a characteristic pattern of gene transcription.
C) Interchromosomal domains act as channels for the movement of proteins, RNAs, and enzymes.
D) Each chromosome occupies exactly the same region in all nuclei within an organism.
E) The largest and most gene- rich chromosomes are located near the center of the nucleus.

Question 13

If nondisjunction occurs in meiosis I of a mother, what proportion of her gametes could have been fertilized by a normal sperm to produce a child with Turner syndrome?

A) 1/4
B) 1/2
C) 0
D) 1
E) 3/4

Question 14

Which of the following is true regarding heterozygous carriers of large chromosome inversions or translocations?

A) They typically have a reduction in the number of viable gametes.
B) They commonly exhibit phenotypic abnormalities.
C) Translocation heterozygotes will produce viable gametes regardless of the pattern of segregation of the involved chromosomes.
D) They should be completely fertile because no genes were deleted.
E) Inversion heterozygotes will only produce viable gametes if they have a paracentric inversion, but not a pericentric inversion.

Question 15

What structure will form during synapsis in Prophase I if there is a partial chromosome deletion or duplication?

A) inversion loop
B) unpaired loop
C) solenoid
D) tetravalent complex
E) nucleosome

Question 16

Donkeys have a somatic chromosome number of 62. Hybrids produced by crossing donkeys and zebras are called zonkeys, are sterile, and have many characteristics intermediate between the two parental species. If a zonkey has 52 chromosomes, what is the somatic chromosome number of zebras?

A) 62
B) 42
C) 52
D) 31
E) 21

Question 17

What technique would you use to detect a target sequence in an intact chromosome using a labeled molecular probe?

A) karyotyping
B) DNA sequencing
C) polymerase chain reaction (PCR)
D) fluorescent in situ hybridization (FISH)
E) western/immuno blotting

Question 18

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

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

Question 19

Given a chromosome with the gene order, A B C D • E F G H, and an inverted chromosome with this gene order, A F E • D C B G H, which of the following recombinant chromosomes would result from a crossover between C and D?

Question 20

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

Question 21

In balanced translocation heterozygotes, viable gametes and progeny are produced by which pattern(s) of chromosome segregation?

A) adjacent- 1 segregation
B) alternate segregation
C) adjacent- 2 segregation
D) both adjacent- 1 and alternate segregation
E) all three patterns of segregation (adjacent- 1, adjacent- 2, and alternate)

Question 22

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

Question 23

Which histone protein is not part of the core nucleosome structure?

A) H1
B) H4
C) H2B
D) H2A
E) H3

Question 24

Which of the following did Hermann Muller determine when studying eye color variegation in Drosophila melanogaster?

A) Transcription of the w+ allele was directly influenced by the level DNA compaction.
B) The w+ allele was expressed in the cell if the heterochromatin spread covered its new location.
C) The chromosome region immediately surrounding the centromere was typically a euchromatic and contains a large number of expressed genes.
D) The pattern of variegation was the same from fly to fly and that the two eyes of a single fly also had the same variegation patterns.
E) The w+ allele had been deleted in cells that produced the white eye patches.

Question 25

Active transcription occurs where with respect to matrix attachment regions (MARs)?

A) within euchromatin regions a large distance from MARs
B) within the telomeres near MARs
C) within euchromatin regions near MARs
D) within heterochromatin regions a large distance from MARs
E) within centromeric heterochromatin near MARs

Question 26

Karyotypes are a method for displaying chromosomes by grouping them into homologous pairs based on what two distinguishing factors?

Question 27

What is the term for the phenomenon that describes the significant reduction, or absence, of recombinant chromosomes in the gametes produced by inversion heterozygotes, when a crossover is within the inverted region?

Question 28

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

Question 29

The flies with variegated eye color had what abnormal chromosome structure?

A) X- chromosome deletion that deleted the w+ gene in some cells following X- ray exposure
B) X- chromosome inversion that moves the w+ gene to a different orientation on the chromosome in some cells following X- ray exposure
C) a mutation in the w+ gene following X- ray exposure that causes the gene to be overexpressed in a tissue- specific manner
D) a mutation in a somatic chromosome that causes the w+ gene to be translocated to the X- chromosomes following X- ray exposure
E) X- chromosome translocation that moves the w+ gene to a region of heterochromatin on another chromosome in some cells following X- ray exposure

Question 30

Which of the following is FALSE regarding individuals who are heterozygous for a large inversion?

A) Crossovers between homologous chromosomes that occur outside the inverted region produce nonviable gametes.
B) Viable gametes will contain either the normal- order chromosome or the inversion- order chromosome.
C) Crossover in the inversion loop of a paracentric inversion heterozygote results in viable and nonviable gametes.
D) Crossover in the inversion loop of a pericentric inversion heterozygote results in gametes with recombinant chromosomes that contain deletions and duplications.
E) There is a higher probability of a crossover that would result in reduced fertility.

Question 31

You are attempting to isolate cells for your karyotype, and you find one cell in each of the phases (prophase, metaphase, anaphase, and telophase). Which one is best suited for a karyotype?

Question 32

How will the centromeres be distributed in the two recombinant chromosomes following a crossover in the inversion loop of a paracentric inversion heterozygote?

Question 33

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

Question 34

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

Question 35

Which of the following best describes the histones associated with eukaryotic DNA?

A) Along a 10,000 base pair segment of DNA, you expect to find twice as many molecules of histone protein H1, as histone protein H4.
B) The amino acid sequences of H4 vary extensively.
C) Within the nucleosome core particle, H1 is the most conserved and crucial histone protein.
D) The five types of histone proteins are small, basic proteins with a positive charge that allows them to bind to DNA.
E) Thousands of base pairs of DNA often wrap around each nucleosome core particle more than a dozen times.

Question 36

A cell can form 10 nm chromatin fibers, but not 30 nm fibers. Which molecule has likely been removed or mutated in this cell?

A) H1
B) H2A
C) H4
D) H3
E) H2B

Question 37

What is meant by the "beads on a string" model of chromatin?

A) The beads are the nucleosomes, and the string is the linker DNA.
B) The beads are molecules of DNA polymerase that attach to the DNA string.
C) The beads are the heterochromatic regions that are tightly compacted, and the strings are euchromatic regions that are being actively transcribed.
D) The beads are ribosomes, and the string is the mRNA that has been transcribed from active chromatin.
E) The beads are the histones, and the string is the transcriptionally active DNA loops.

Question 38

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

Question 39

Which of the following correctly lists the levels of compaction in eukaryotes from naked DNA to the most compact?

A) nucleosome, looped chromatin (300- nm fiber), metaphase chromosome, solenoid
B) nucleosome, solenoid, looped chromatin (300- nm fiber), metaphase chromosome
C) metaphase chromosome, nucleosome, solenoid, looped chromatin (300- nm fiber)
D) solenoid, metaphase chromosome, nucleosome, looped chromatin (300- nm fiber)
E) solenoid, nucleosome, looped chromatin (300- nm fiber), metaphase chromosome

Question 40

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

Question 41

If you want to prevent chromatin loops from being anchored to the chromosome scaffold, which regions of the DNA would you target?

Question 42

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

Question 43

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

Question 44

There is clear evidence that chromatin state is directly related to the ability of transcriptionally active proteins to initiate gene transcription. Compare and contrast euchromatin to heterochromatin in the context of transcription.

Question 45

Nucleosomes are comprised of how many molecules of histones?

Question 46

After DNA replication, during reassembly of nucleosomes, the tetramers are bound by H2A- H2B dimers to form complete nucleosomes.

Question 47

Which proteins would you target if you wanted to disrupt the chromosome superstructure for chromatin condensation that ultimately produces the characteristic shape of the metaphase chromosome?

Question 48

The figure shows the structure of a series of fruit fly deletion mutants. The gap in each line represents the segment of the chromosome that is deleted in each mutant. Stains that were heterozygous for each deletion mutation and a point mutation (A, B, C, D, E, and
F) were created and analyzed for wild- type (+) or mutant (- ) phenotypes. The results of the analyses are shown in the table.
Which of the following is the correct order of the six point mutations on the chromosome?

Question 49

In individuals heterozygous for a reciprocal balanced translocation, adjacent- 2 segregation of tetravalent structures is very rare since it requires which type of centromeres to move to the same pole of the cell at anaphase I?

Question 50

What is the name of the structure formed when the 10 nm fibers of chromatin form a cylindrical filament of coiled nucleosomes?

Question 51

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

Question 52

Eukaryotic chromosomes are a combination of proteins and DNA, which allows the cell to perform which four essential functions?

Question 53

Histone proteins are the principal agents in chromatin packaging. The nucleosome core particle is a heterooctam protein complex that contains two molecules each of the four histones H2A, H2B, H3, and H4. Describe the proce managing existing nucleosome core particles during replication and the process of adding these and new nucleo core particles to DNA after the replication
fork passes.

Question 54

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

Question 55

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 56

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

Question 57

is used to map genes in deleted chromosome regions by a method known as deletion mapping. It 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.