Deck 19: The Cell Cycle, DNA Replication, and Mitosis

Question 1

The phase of the cell cycle associated with the doubling of the amount of DNA in the cell is

A)G0.
B)G1.
C)G2.
D)M.
E)S.

Answer 1

E

Question 2

In the cell cycle,a mitotic Cdk is present during

A)G1.
B)G2.
C)M.
D)S.
E)all of the above

Answer 2

E

Question 3

A population of T cells has been stimulated to proliferate in response to a particular antigen.A sample of 1000 cells is examined microscopically,revealing that 200 of these cells are in the various stages of mitosis.Of the remaining 800 in interphase,400 have x amount of DNA,250 have 2x,and the remaining 150 have amounts somewhere between x and 2x.Additional analysis reveals that the G2 phase of the cell cycle lasts 2 hours.What is the total length of the cell cycle?

A)2.5 hours
B)4 hours
C)6.4 hours
D)8 hours
E)13.3 hours

Answer 3

D

Question 4

An isolate of a mutant bacterium appears to grow more slowly than the population (wild type)from which it was isolated.Further studies showed that the slower growth was due to a markedly reduced DNA polymerase I activity.From this information,one would expect that this organism would also be deficient in the activity of DNA

A)excision repair.
B)recombination.
C)transcription.
D)translation.
E)unwinding.

Question 5

A mutant strain of yeast possesses a mutation in the nda2 gene,resulting in no production of α1 tubulin.As a result,these cells would most likely

A)not duplicate their chromosomes.
B)not enter M phase.
C)not enter S phase.
D)keep the nuclear membrane intact.
E)have little or no spindle formation.

Question 6

A NASA probe returned samples of rocks from the surface of Mars.From these rocks,a prokaryotic organism was isolated and remained viable under conditions similar to that of Mars.The organisms are capable of dividing to replicate themselves.In order to determine whether the DNA replication of these organisms was semiconservative,an experiment using N15/N14 (similar to that of Mendelson and Stahl)was performed.If the method of DNA replication were conservative,after one generation one would expect to see

A)all of the DNA in the heavy (N¹⁵)band.
B)all of the DNA in the light (N¹⁴)band.
C)all of the DNA at a point midway between the heavy and light bands.
D)half of the DNA in the light band, the other half in the heavy band.
E)none of the above

Question 7

Using polyethylene glycol (PEG),early G1 phase cells were fused with S phase cells.Of the following events,which would you expect to be induced in the G1 cells as a result of the fusion?

A)cytokinesis
B)condensation of chromosomes
C)DNA replication
D)mitosis
E)spindle fiber formation

Question 8

The phase of the cell cycle associated with the replication of DNA is

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

Question 9

All of the following are associated with replicons except

A)origin of replication.
B)single-strand binding proteins.
C)initiator proteins.
D)minichromosome maintenance proteins.
E)helicase loaders.

Question 10

Ultraviolet (UV)light-treated bacteria would most likely have DNA damage in the form of

A)analog incorporation.
B)pyrimidine dimer formation.
C)intercalation of the bases.
D)direct transition of the bases.
E)deamination.

Question 11

A particular strain of yeast produces strains with a mutant cdC₂ gene,resulting in little to no production of the CdC₂ protein kinase.As a result,one would expect that these cells would

A)not enter M phase.
B)not have the nuclear envelope disperse.
C)lack chromosome condensation.
D)all of the above
E)none of the above

Question 12

Which of the following statements regarding DNA replication is true?

A)Bacterial replication is faster than eukaryotic replication.
B)DNA replication during embryonic development occurs at a slower rate than in the early stages of neonatal life.
C)Early-replicating genes are those that are not actively transcribed.
D)The rate of DNA replication is constant at all stages of development in eukaryotes.
E)Cyclin-dependent kinases (Cdk)are not involved in the DNA replication process.

Question 13

All of the following circular DNAs exhibit theta replication except

A)bacteria.
B)mitochondria.
C)chloroplasts.
D)plasmids.
E)protists.

Question 14

What is the ploidy of an organism that is 7n,where n = 5?

A)5
B)7
C)12
D)35
E)57

Question 15

DNA replication

A)requires a type of RNA polymerase.
B)is partially regulated by promoter/terminator sites.
C)proceeds by making two continuous strands.
D)is not edited once polymerization has occurred.
E)is conservative.

Question 16

During metaphase of mitosis,how many telomeres are present in a cell in which 2n = 12?

A)6
B)12
C)24
D)48
E)1200

Question 17

Cyclins modulate the progression of cells through the cell cycle by

A)directly activating G proteins.
B)inducing synthesis of constitutively active forms of growth cell receptors.
C)activating protein kinases that are critical regulators of cell division.
D)degrading histones.
E)increasing the production of DNA polymerases.

Question 18

During the G2 checkpoint in eukaryotic cells,the cell is assessed with regard to

A)DNA replication.
B)chromosome attachment to the spindle.
C)nutrients.
D)DNA damage.
E)presence of growth factors.

Question 19

In a cell with a diploid number of 12,how many chromatids are present at prophase of mitosis?

A)6
B)12
C)24
D)48
E)none of the above

Question 20

DNA replication is

A)conservative.
B)dispersive.
C)semiconservative.
D)irregular.
E)none of the above

Question 21

The multiple sites of DNA replication along eukaryotic chromosomes are known as

A)replicons.
B)multireplication forks.
C)helicase loaders.
D)ARS elements.
E)none of the above

Question 22

Which of the following families of proteins is associated with the contractile ring?

A)rho
B)alpha
C)sigma
D)kappa
E)delta

Question 23

Ras is to Raf,as MEK is to

A)Ras.
B)tyrosine.
C)MAPK.
D)Cdc.
E)cell growth.

Question 24

In the cell cycle,controlled degradation of regulatory proteins occurs via the

A)P₄₅₀ - protease pathway.
B)cyclin proteolysis pathway.
C)ubiquitin-proteosome pathway.
D)kinase inhibition pathway.
E)none of the above

Question 25

The longest phase of the cell cycle is

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

Question 26

Which of the following statements regarding Fas-mediated programmed cell death is false?

A)Fas ligand binding with Fas receptor stimulates a specific G protein.
B)Fas ligand and receptor interaction results in the recruitment of adaptor proteins in the target cell.
C)Capases are activated in the process.
D)The caspase cascade results in the cleavage of the proteins within the target cell.
E)It ultimately results in death of the cell.

Question 27

Which of the following proteins is observed exclusively in association with eukaryotic DNA replication?

A)DNA polymerase I
B)DNA gyrase
C)single-strand binding proteins
D)DNA ligase
E)telomerase

Question 28

The phase of the cell cycle that varies most in duration in various cell types is

A)M.
B)G₁.
C)S.
D)G₂.
E)both choices A and B

Question 29

Killer lymphocytes can elicit self-destruct mechanisms in target cells by interacting with

A)Fas ligand.
B)Fas receptors.
C)Ras ligand.
D)adaptor proteins.
E)procaspase.

Question 30

Mice lacking the ability to make caspase-9 die as the result of numerous defects.During the necropsy (animal autopsy)of the animal you note that the brains of these mice are

A)unregulated growth of the nerve cells.
B)lack of apoptosis of some cells.
C)overstimulation of G-protein-mediated transduction.
D)overproduction of the Etr1 receptor protein.
E)all of the above

Question 31

All of the following participate in apoptosis except

A)caspases.
B)death-promoting proteins.
C)mitochondria.
D)Bcl-2.
E)calcium ions.

Question 32

Which of the following would not inhibit a cell preparing to undergo mitosis?

A)chromosomal abnormalities
B)Cdc-activating kinase activity
C)Chk1 inhibtion of Cdc25
D)p21 inhibition of G₁
E)environmental signals that no new cells are needed

Question 33

In order to be active,a Cdc-cyclin needs to be

A)singly phosphorylated.
B)acetylated.
C)doubly phosphorylated.
D)doubly methylated.
E)cleaved by proteases.

Question 34

Which of the following eukaryotic DNA polymerases replicates mitochondrial DNA?

A)alpha
B)beta
C)delta
D)epsilon
E)gamma

Question 35

Phosphorylation of ________ is required for chromosome condensation.

A)condensin
B)cyclin
C)DNA gyrase
D)topoisomerase II
E)both choices A and B

Question 36

The proteins most actively synthesized during the S phase of the cell cycle are

A)DNA polymerases.
B)rRNA proteins.
C)histones.
D)single-strand binding proteins.
E)cyclins.

Question 37

Which of the following proteins is observed exclusively in association with prokaryotic DNA replication?

A)DNA polymerase I
B)primase
C)helicase
D)single-strand binding proteins
E)telomerase

Question 38

DNA repair in eukaryotes that facilitates replication in regions of thymine dimers is mediated by a unique DNA polymerase

A)α.
B)η.
C)β.
D)σ.
E)δ.

Question 39

The protein(s)that facilitate the unfolding of chromatin fibers ahead of the replication fork is (are)

A)helicase.
B)scaffold proteins.
C)chromatin remodeling proteins.
D)replisomal proteins.
E)both choices A and B

Question 40

Which enzyme is involved in proofreading during DNA replication?

A)5' to 3' exonuclease
B)3' to 5' exonuclease
C)5' to 3' endonuclease
D)3' to 5' endonuclease
E)DNA polymerase

Question 41

The region of the centromere contains repeated DNA sequences known as ________.

Question 42

________ synthesis is a damage-tolerant mechanism that allows synthesis of a new DNA strand from a damaged template.

Question 43

Several human disorders are caused by DNA repair pathway deficiencies. Choose one and describe: 1)what the deficiency is and 2)how the defect could be corrected.

Question 44

The type of DNA repair that fixes mistakes in nucleotide incorporation is known as ________ repair.

Question 45

Proteins bound to CEN sequences form a complex known as the ________.

Question 46

Why does DNA contain thymine over uracil? What effect would the presence of uracil in the DNA have on repair?

Question 47

The ________ pathway uses a set of proteins that bind to ends of two broken DNA fragments and join them together.

Question 48

DNA replication of linear chromosomes has multiple sites known as ________.

Question 49

________ is a new technique that has facilitated cell cycle studies.

Question 50

At least one aspect of aging has been determined to be the shortening of the ________ with each successive round of cell division.

Question 51

A way of making multiple copies of a segment of DNA from a single template is known as ________.

Question 52

Analysis of chromosomes in metaphase of mitosis is known as ________ .

Question 53

Why do eukaryotic chromosomes have multiple origins of replication? Design an experiment that allows you to test your hypothesis.

Question 54

Small pieces of DNA synthesized on the lagging strand are called ________.

Question 55

Using specific examples,distinguish between those mutations that are spontaneous and those that are the result of exposure to substances.How might some of the exposures be used in cellular biology?

Question 56

Starting with a cell (2n = 4),illustrate the phases of mitosis with emphasis on the division of chromosomes.

Question 57

Telomerases are important in the replication of linear chromosomes because there is no ________ at the ends of the lagging strands.

Question 58

The ________ leads to the release of importin-bound proteins and stimulates microtubule assembly.