question

In eukaryotic cells, chromosomes are composed of

answer

DNA and proteins

question

What is the final result of mitosis in a human sell

answer

genetically identical 2n somatic cells

question

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells

answer

32

question

If there are 20 duplicated chromosomes in a cell how many centromeres are there

answer

20

question

Scientists isolate cells in various phases of the cell cycle. They find a group of cells that have 1.5 times more DNA than G1 phase cells. The cells of this group are

answer

in the S phases of the cell cycle

question

The first gap in the cell cycle G1 corresponds to

answer

normal growth and cell function

question

The microtubule-organizing center found in animal cells is an identifiable structure present during all phases of the cell cycle. Specifically, it is known as the

answer

centrosome

question

In humankind many other eukaryotic species' cells, the nuclear membrane has to disappear to permit

answer

the attachment of microtubules to kinetochores

question

The mitotic spindle is a micro tubular structure that is involved in

answer

separation of sister chromatids

question

Metaphase is characterized by

answer

aligning of chromosomes on the equator

question

Kinetochore microtubules assist in the process of splitting centromere by

answer

creating tension by pulling toward opposite poles

question

Some cells have several nuclei per cell. How could such multinucleate cells be explained?

answer

the cell underwent repeated mitosis, but cytokinesis did not occur

question

How is plant cell cytokinesis different from animal cell cytokinesis

answer

Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow.

question

FtsZ is a bacterial cytoskeletal protein that forms a contractile ring involved in bacterial cytokinesis. Its function is analogous to _____.

answer

the cleavage furrow of eukaryotic animal cells

question

At which phase are centrioles beginning to move apart in animal cells?

answer

prophase

question

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?

answer

10

question

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly, this stops mitosis. Specifically, Taxol must affect _____.

answer

the structure of the mitotic spindle

question

Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?

answer

Golgi-derived vesicles

question

Movement of the chromosomes during anaphase would be most affected by a drug that prevents _____.

answer

shortening of microtubules

question

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?

answer

G2

question

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?

answer

16;16

question

The beginning of anaphase is indicated by which of the following?

answer

Cohesin is cleaved enzymatically.

question

During which phase of mitosis do the chromatids become chromosomes?

answer

anaphase

question

A cleavage furrow is _____.

answer

groove in the plasma membrane between daughter nuclei

question

The research team used their experiments to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that _____.

answer

infection causes lymphocytes to divide more rapidly

question

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely _____.

answer

a plant cell in the process of cytokinesis

question

Which of the following does NOT occur during mitosis?

answer

replication of the DNA

question

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?

answer

cleavage furrow formation and cytokinesis

question

Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle?

answer

ATP as an energy source

question

Neurons and some other specialized cells divide infrequently because they _____.

answer

have entered into G0

question

MPF is a dimer consisting of _____.

answer

cyclin and a cyclin-dependent kinase

question

Cyclin-dependent kinase (Cdk) is _____.

answer

an enzyme that attaches phosphate groups to other proteins

question

What happens if MPF (mitosis-promoting factor) is introduced into immature frog oocytes that are arrested in G2?

answer

The cells enter mitosis.

question

Once a cell completes mitosis, molecular division triggers must be turned off. What happens to MPF during mitosis?

answer

The cyclin component of MPF is degraded.

question

The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in _____.

answer

metaphase

question

Which of the following is released by platelets in the vicinity of an injury?

answer

PDGF

question

Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?

answer

cyclin

question

Which of the following is a protein maintained at steady levels throughout the cell cycle that requires cyclin to become catalytically active?

answer

CDK

question

Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?

answer

MPF

question

The cyclin component of MPF is destroyed toward the end of which phase?

answer

M

question

Density-dependent inhibition is explained by which of the following?

answer

As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.

question

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?

answer

lack of appropriate cell death

question

Anchorage dependence of animal cells in vitro or in vivo depends on which of the following?

answer

response of the cell cycle controls to signals from the plasma membrane

question

A research team began a study of a cultured cell line. Their preliminary observations showed them that the cell line did not exhibit either density-dependent inhibition or anchorage dependence. What could they conclude right away?

answer

The cells show characteristics of tumors.

question

For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable?

answer

It interferes with rapidly dividing cells.

question

Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?

answer

Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.

question

Exposure of zebrafish nuclei to meiotic cytosol resulted in phosphorylation of NEP55 and L68 proteins by cyclin-dependent kinase 2. NEP55 is a protein of the inner nuclear membrane, and L68 is a protein of the nuclear lamina. What is the most likely role of phosphorylation of these proteins in the process of mitosis?

answer

They are involved in the disassembly of the nuclear envelope.

question

Density-dependent inhibition is a phenomenon in which crowded cells stop dividing at some optimal density and location. This phenomenon involves binding of a cell-surface protein to its counterpart on an adjoining cell's surface. A growth inhibiting signal is sent to both cells, preventing them from dividing. Certain external physical factors can affect this inhibition mechanism.

answer

As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth.

question

The centromere is a region in which

answer

chromatids remain attached to one another until anaphase.

question

What is a chromatid?

answer

a replicate chromosome

question

For a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission?

answer

Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes.

question

How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?

answer

The daughter cells have the same number of chromosomes and the same amount of DNA.

question

Which term describes centrioles beginning to move apart in animal cells?

answer

prophase

question

Which is the longest of the mitotic stages?

answer

metaphase

question

Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell?

answer

anaphase

question

If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested?

answer

metaphase

question

A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosomes?

answer

46

question

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?

answer

centrosome

question

If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have during anaphase?

answer

16

question

Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with

answer

two nuclei

question

Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants

answer

a cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage.

question

The formation of a cell plate is beginning across the middle of a cell and nuclei are re-forming at opposite ends of the cell. What kind of cell is this?

answer

a plant cell undergoing cytokinesis

question

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, taxol must affect

answer

the fibers of the mitotic spindle.

question

During which phases of mitosis are chromosomes composed of two chromatids?

answer

from G2 of interphase through metaphase

question

In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis?

answer

dinoflagellates and diatoms

question

Imagine looking through a microscope at a squashed onion root tip. The chromosomes of many of the cells are plainly visible. In some cells, replicated chromosomes are aligned along the center (equator) of the cell. These particular cells are in which stage of mitosis?

answer

metaphase

question

In order for anaphase to begin, which of the following must occur?

answer

Cohesin must be cleaved enzymatically.

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