Deck 11: The Eukaryotic Chromosome

Question 1

In mammalian cells, replication proceeds

A)unidirectionally
B)bidirectionally.
C)unidirectionally from many origins.
D)bidirectionally from only one origin.

Answer 1

bidirectionally.

Question 2

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

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

Answer 2

10,000

Question 3

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

A)at least one per loop of DNA.
B)probably one every other loop of DNA
C)a random distribution across the genome.
D)a precise pattern of distribution relative to other replication points

Answer 3

at least one per loop of DNA.

Question 4

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 5

The components of a chromosome include one long DNA molecule and

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

Question 6

At what stage of mitosis do we first see a chromosome that is compacted 250-fold over the 40-fold compacted 300Å fiber?

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

Question 7

Telomeres appear to function in at least two ways during the replication of chromosomes.One way is to provide a primer for DNA polymerase.The second is to

A)allow the chromosome to shorten each generation to speed up replication.
B)bind to telomerase.
C)permit the hairpin turn at the end to be cleaved.
D)carry genes needed for DNA replication.

Question 8

In DNA, the 300Å 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.

Question 9

Which of the following is not a role ascribed to nonhistone proteins found in chromatin?

A)structural
B)replication
C)chromosome segregation
D)nucleosome packers

Question 10

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, 2,000
B)300, 1,000
C)100, 2,000
D)100, 1,000

Question 11

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 12

Which of the following is not a piece of evidence that supports the radial loop-scaffold model of DNA packaging?

A)Histone-depleted metaphase chromosomes still maintain their X-like shapes.
B)Electron micrographs of whole-mounted mitotic chromosomes show loops of chromatin at the periphery of the chromosomes.
C)Topoisomerase II assists in 100Å packaging.
D)Special, irregularly spaced repetitive base sequences associate with nonhistone proteins to define the chromatin loops.

Question 13

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)1/3 DNA, 1/3 histones, and 1/3 basic proteins.
D)1/4 DNA, 1/4 RNA, 1/4 histones, and 1/4 nonhistones.

Question 14

Which of the following is NOT true about DNA polymerase?

A)It cannot begin the 5' end of a new strand without a primer.
B)It can only travel in the 5' to 3' direction.
C)It can reconstruct the 3' end of each newly made DNA strand.
D)It can replace RNA primer with DNA at the 5' end.

Question 15

With regard to the typical human cell, which of the following appears to be true?

A)There is only one origin of replication.
B)There are multiple origins of replication that function consecutively.
C)There are multiple origins of replication that function simultaneously.
D)Replication is not understood well enough to postulate on replication origins.

Question 16

Comparison of the chromosome banding pattern of humans and which other primate have banding patterns nearly identical on 13 of the chromosomes?

A)gorilla.
B)chimpanzee.
C)orangutan.
D)baboon.

Question 17

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)high level compaction into metaphase-type chromosomes.
D)histone, DNA, and nonhistone covalent bonding.

Question 18

Which of the following is not usually seen when a cell loses telomerase activity?

A)Telomeres shorten slightly with each cell division.
B)After 30-50 divisions, cells show signs of senescence and then die.
C)In the immune system, certain capacity for protection is gradually lost.
D)Many normal somatic cells gain the ability to divide indefinitely.

Question 19

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 20

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 21

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 sample cannot be digested by DNAse.
E)The sample likely represents actively transcribed genes.

Question 22

Cohesins are a multisubunit protein complex that functions to

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

Question 23

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 24

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 25

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

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

Question 26

The single-celled yeast, Saccharomyces cerevisiae, was the organism of choice as raw material for constructing artificial chromosomes because of all the following except that

A)it is easy to manipulate.
B)it is unicellular.
C)its genetic machinery is similar to the one in higher organisms.
D)its origins of replication have been defined as discrete, small segments of DNA.

Question 27

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 28

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 29

In DNA, most satellite sequences are found in

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

Question 30

In the position effect variegation of red and white eye color in Drosophila, eyes are produced

A)one red and one white.
B)red or white depending on which gene is dominant.
C)with every other eye facet red or white.
D)with varying sizes and positions of red and white patches.

Question 31

One of the functions of a centromere is to contribute to 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)develop meiotic chromosome replication.

Question 32

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 33

From DNA research, 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 34

When constructing a YAC, why must a large amount of random DNA be included?

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

Question 35

A yeast artificial chromosome (YAC) usually consists of

A)a yeast centromere.
B)a yeast origin of replication.
C)telomere sequences.
D)suitable selectable markers.
E)All of the choices are correct.

Question 36

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

A)The chromosomes will dissociate from 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 37

During mitosis, kinetochores develop during

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

Question 38

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 is the most recessive.

Question 39

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)play various roles in chromosome segregation.

Question 40

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

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

Question 41

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 different chromnosomes during metaphase.
C)A method to fluorescently label heterochromatin..
D)A method to fluorescently label euchromatin..

Question 42

What is true about new nucleosome formation during DNA replciation?

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 synhtesized octamers and the other will have previously synthesized octamers.
D)Nucleosomes will be composed of different combinations of H2A/H2BH3/H4 tetramers that are either newly synthesized or were from previous histone octamers.

Question 43

What is the structure of telomeres?

A)Short, repetetive DNA sequences found at the end of linear eukaryotic chromosomes.
B)Long, repetetive DNA sequences found at the end of linear eukaryotic chromosomes.
C)Short, repetetive DNA sequences found at the end of linear prokaryotic chromosomes.
D)Long, unique DNA sequences found at the end of linear eukaryotic chromosomes.