Deck 12: The Eukaryotic Chromosome

Question 1

The 10,000 origins of replication in mammalian cells suggests that there is

A)at least one origin of replication per loop of DNA.
B)probably one origin of replication every other loop of DNA
C)a random distribution of origins of replication across the genome.
D)an even distribution of origins of replication across the genome.

Answer 1

A

Question 2

In a typical human cell, DNA polymerase synthesizes DNA at a rate of approximately 50 nucleotides per second.Human chromosome 1 contains about 250 million base pairs.If a single origin of replication were used, how long would it take the cell to copy this chromosome?

A)less than 24 hours
B)1 to 2 days
C)1 to 2 weeks
D)50 to 60 days
E)110 to 120 days

Answer 2

D

Question 3

Telomeres have at least two roles in chromosome integrity.Telomeres are composed of repeat sequences homologous to the RNA in telomerase used to replicate chromosome ends.Second, they

A)allow the chromosome to shorten each generation to speed up replication.
B)interact with shelterin complexes that protect chromosome ends from degradation.
C)permit the hairpin turn at the end to be cleaved.
D)carry genes needed for DNA replication.

Answer 3

B

Question 4

In DNA, the 300 Å fiber is formed into structural loops.Responsibility for this function appears to lie with

A)histone H4.
B)nucleosomase.
C)histone H1.
D)certain nonhistone proteins.
E)remodeling complexes.

Question 5

In what stage of mitosis are the highly-compacted chromosomes used for FISH?

A)prophase
B)metaphase
C)anaphase
D)telophase
E)never achieves this level of compaction

Question 6

The first level of compaction of DNA consists of

A)DNA winding around histones to form small nucleosomes.
B)tight coiling of DNA with nucleosomes into higher order structures.
C)compaction into metaphase chromosomes.
D)histone, DNA, and nonhistone covalent bonding.

Question 7

The enzyme that some organisms use to replicate DNA at the 5' ends of chromosomes is called

A)DNA polymerase.
B)telomerase.
C)DNA ligase.
D)replicase.

Question 8

The histone that appears to be responsible for organizing the 100 Å fibers into 300 Å fibers is

A)H4.
B)H3.
C)H2.
D)H1.

Question 9

Yeast research with autonomously replicating sequences (ARS), along with digestion of chromatin with DNase I, have led scientists to determine that

A)DNA is not protected inside a nucleosome.
B)ARSs are really plasmids.
C)ARSs bond irreversibly to replication enzymes.
D)origins of replication are accessible regions of DNA devoid of nucleosomes.

Question 10

Histones and DNA have a strong attraction for each other because

A)DNA is positively charged and histones are negatively charged.
B)both DNA and proteins are hydrophobic.
C)DNA is negatively charged and histones are positively charged.
D)like substances share common charges.

Question 11

The technique of preparing mitotic chromosomes involves a staining procedure using Giemsa stain.One variation of this technique allows a low-resolution of chromosome bands while a second variation allows a high resolution.At low resolution we can see about ________ bands while at high resolution we see about ________ bands.

A)300; 2000
B)300; 1000
C)100; 2000
D)100; 1000

Question 12

The two chromatids of each replicated chromosome must separate from one another and segregate during

A)mitosis.
B)meiosis I.
C)meiosis II.
D)both mitosis and meiosis I.
E)both mitosis and meiosis II.

Question 13

Select the statement that correctly describes the roles of histone and nonhistone proteins found in chromatin?

A)Only histones have a structural role in chromatin.
B)Only nonhistone proteins have a structural role in chromatin.
C)Histone proteins function primarily in chromosome segregation.
D)Both histone and nonhistone proteins have a structural role in chromatin.
E)Nonhistone proteins function only in replication and chromosome segregation.

Question 14

By weight, chromatin consists roughly of

A)1/3 DNA, 1/3 histones, and 1/3 nonhistones.
B)1/3 DNA and 2/3 acidic proteins.
C)1/2 DNA, 1/4 histones, and 1/4 basic proteins.
D)1/4 DNA, 1/4 RNA, 1/4 histones, and 1/4 nonhistones.

Question 15

When a cell loses telomerase activity, what is the predicted effect?

A)Telomeres will increase slightly with each cell division.
B)After 30-50 divisions, the cell will show signs of senescence and then die.
C)An immune stem cell will increase white blood cell production.
D)A normal somatic cell will gain the ability to divide indefinitely.
E)The cell will die immediately.

Question 16

In mammalian cells, replication proceeds

A)unidirectionally
B)bidirectionally.
C)unidirectionally from many origins.
D)bidirectionally from a single origin.

Question 17

Which pieces of evidence support the radial loop-scaffold model of DNA packaging?

A)Histone-depleted metaphase chromosomes still maintain their X-like shapes.
B)Radial loop-scaffold DNA has been isolated and crystallized.
C)Topoisomerase II assists in 100 Å packaging.
D)Each G band formed by Giemsa staining represents a chromatin loop.

Question 18

The components of a chromosome include one long DNA molecule and

A)phospholipids.
B)proteins.
C)carbohydrates.
D)steroids.
E)chromophores.

Question 19

The total compaction of DNA as seen in metaphase chromosomes is approximately ________-fold.

A)10,000
B)50,000
C)100,000
D)40

Question 20

During DNA replication in a typical human cell,

A)only one origin of replication exists for each chromosome.
B)multiple origins of replication function consecutively.
C)multiple origins of replication function simultaneously.
D)the origins of replication are at the centromeres.
E)the origins of replication are at the telomeres.

Question 21

Cohesins are multisubunit protein complexes that

A)hold sister chromatids together.
B)ensure that proper chromosome arm length is maintained.
C)allow easy karyotyping.
D)allow replication of chromosome ends.

Question 22

One of the functions of a centromere is to form kinetochores for proper chromosome segregation.The other function is to

A)hold sister chromatids together.
B)ensure that proper chromosome arm length is maintained.
C)allow easy karyotyping.
D)allow replication of chromosome ends.

Question 23

When a chromosomal rearrangement, such as an inversion, places a known gene into or next to a heterochromatic region, the gene's transcription

A)will turn on.
B)may be amplified.
C)may cease.
D)may be inverted.

Question 24

In DNA, most satellite sequences are found in

A)chromosome arms.
B)telomeres.
C)centromeres.
D)spaces around the dark bands.

Question 25

During development, an XX female embryo will form one of the X chromosomes in each cell into a Barr body.This usually occurs

A)about two weeks after zygote formation.
B)by the end of the first trimester.
C)at the 16-cell stage.
D)in the X that has the most recessive alleles.

Question 26

Sites of transcription and therefore most of the genes along the length of the chromosome appear to be found in

A)heterochromatin.
B)euchromatin.
C)constitutive heterochromatin.
D)centromeric regions.

Question 27

In higher eukaryotes, kinetochores attach to

A)one spindle fiber.
B)one spindle fiber on each side.
C)multiple spindle fibers.
D)multiple repeating structural subunits.

Question 28

FISH analysis is useful for determining the

A)order of DNA fragments in a BAC.
B)pattern of expression of a cloned gene.
C)chromosomal location of a gene.
D)map order of two closely linked genes.

Question 29

You treat a sample of DNA with DNase and run the digested fragments out on an electrophoretic gel.You found mostly long fragments.What can you conclude about this sample of DNA?

A)The sample contains mostly euchromatin.
B)The sample contains relatively few histone proteins.
C)The sample contains mostly heterochromatin.
D)The DNA is from yeast cells.
E)The sample likely represents actively transcribed genes.

Question 30

You are studying a histone complex that contains an unusually high level of modification with acetyl groups.What can you conclude about the DNA bound to this histone complex?

A)It contains actively transcribed genes.
B)It is most likely heterochromatin.
C)It is most likely telomeric.
D)It is most likely derived from a condensed Barr body.

Question 31

During mitosis, kinetochores develop during

A)telophase.
B)anaphase.
C)metaphase.
D)prophase.

Question 32

Which of the following is a predicted consequence of kinetochores not achieving the correct level of tension from the mitotic spindle?

A)Sister chromatids will no longer be held together at their centromeres.
B)All chromosomes will migrate to one pole instead of to two opposite poles.
C)Mitosis will not progress beyond metaphase.
D)No prediction can be made.

Question 33

Position-effect variegation of red and white eye color in Drosophila produces

A)one red eye and one white eyes.
B)two red or two white eyes depending on which gene is dominant.
C)eyes alternating red and white eye facets.
D)eyes with red and white patches of varying sizes and positions.

Question 34

What is the best definition for the FISH technique?

A)A method to fluorescently label different genes on metaphase chromosomes.
B)A method to fluorescently label methylated histones associated with chromosomes.
C)A method to fluorescently label heterochromatin.
D)A method to fluorescently label euchromatin.

Question 35

In which of the following cases will a Barr body be seen?

A)only XX
B)XY
C)XO
D)only XXY
E)both XX and XXY

Question 36

When constructing a YAC, why must a large DNA insert be included?

A)The inserted DNA base pairs with DNA in the genome.
B)YACs that are too small do not segregate properly during mitosis.
C)The inserted DNA functions as telomeres.
D)The inserted DNA contains origins of replication needed for maintenance of the YAC.
E)The inserted DNA allows YACs to be used in both eukaryotic and prokaryotic cells.

Question 37

In yeast chromosomes, centromeres

A)help distinguish one chromosome from another.
B)are closely related in sequence.
C)are only 10-15 bp long.
D)contain satellite DNA.

Question 38

Which of the combinations represents a complete yeast artificial chromosome (YAC)that is most likely to segregate correctly?

A)telomere-ARS-centromere
B)telomere-ARS-centromere-100,000 bp insert
C)telomere-centromere-100,000 bp insert-telomere
D)telomere-ARS-centromere-11,000 bp insert-telomere suitable selectable markers
E)telomere-ARS-centromere-100,000 bp insert-telomere

Question 39

The single-celled yeast, Saccharomyces cerevisiae, was used to construct the first eukaryotic artificial chromosome.This was a significant achievement because

A)yeast centromeres are identical to human centromeres.
B)it defined chromosomal regions that serve as centromeres and origins of replication in yeast.
C)it revealed the rate of DNA replication in yeast.
D)it demonstrated that some yeast genes are not essential.
E)it defined the chromosomal region with the TRP⁺ gene for tryptophan synthesis in yeast.

Question 40

Which of the following predictions could you make about a cell in which the HP1 protein was disabled?

A)Methylation of DNA would increase.
B)All of the cell's chromosomes would be completely condensed into heterochromatin.
C)Histone methyltransferase would bind to chromatin more easily.
D)Heterochromatin would not be formed.

Question 41

Suppose a cell lacks functional Shugoshin.What is the predicted effect on cohesin?

A)Cohesin will be cleaved prior to metaphase in mitosis.
B)Cohesin will not be cleaved during mitosis or meiosis.
C)Cohesin at the centromeres of sister chromatids will be cleaved during meiosis I.
D)Cohesin on the arms of sister chromatids will be cleaved during meiosis II.
E)Cohesin will be cleaved normally during mitosis and meiosis I.

Question 42

The technique of preparing mitotic chromosomes involves a staining procedure using Giemsa stain.In this procedure, chromosomes are first ________ and then exposed to stain, producing ________ in a standard human karyotype.

A)heated; hundreds of reproducible bands
B)heated; thousands of reproducible bands
C)fragmented; hundreds of reproducible bands
D)fragmented; hundreds of variable bands

Question 43

The creation of yeast artificial chromosomes preceded the production of the first yeast

A)synthetic chromosome that includes sequences from the human genome.
B)synthetic chromosome that lacks about 50,000 bp from the normal yeast third chromosome.
C)essential chromosome that combines the 1000 essential yeast genes into one chromosome.
D)circular chromosome that does not require telomere sequences.

Question 44

A barrier element between a gene and heterochromatin would prevent that gene from being transcriptionally silenced by heterochromatin spreading.

Question 45

What is the structure of telomeres?

A)short, repetitive DNA sequences found at the ends of linear eukaryotic chromosomes
B)long, repetitive DNA sequences found at the ends of linear eukaryotic chromosomes
C)short, repetitive DNA sequences found at the ends of linear prokaryotic chromosomes
D)long, unique DNA sequences found at the ends of linear eukaryotic chromosomes

Question 46

Methylated histone tail amino acids are associated with chromatin that is

A)either open or closed.
B)open only.
C)closed only.
D)newly replicated.
E)about to replicate.

Question 47

Kinetochores include motor proteins that exert pulling forces on spindle microtubules.

Question 48

What is true about new nucleosome formation during DNA replication?

A)Nucleosomes will be composed of different combinations of H3/H4 tetramers and H2A/H2B that are either newly synthesized or were from previous histone octamers.
B)Nucleosomes will be composed of different combinations of H3/H2A tetramers and H4/H2B that are either newly synthesized or were from previous histone octamers.
C)One DNA strand will have newly synthesized octamers and the other will have previously synthesized octamers.
D)Nucleosomes will be composed of different combinations of H2A/H2B/H3/H4 tetramers that are either newly synthesized or were from previous histone octamers.

Question 49

Acetylated histone tail lysines are associated with chromatin that is

A)open.
B)closed.
C)transcriptionally inactive.
D)newly replicated.
E)about to replicate.

Question 50

The position of a gene located within a light G band on the short arm of chromosome 5 could be designated as

A)5p13-pter.
B)5p13-qter.
C)p513.
D)5q13-qter.
E)q513.

Question 51

Which statement correctly describes the similarity of centromeres in different organisms?

A)Both yeast and plant centromeres have two 10-to-15 bp conserved elements.
B)Yeast centromeres have fewer satellite DNA repeats than do human centromeres.
C)Both human and plant centromeres are composed of repeated satellite DNA sequences.
D)Yeast centromeres have fewer satellite DNA repeats than do plant centromeres.