Mastering Chapter 12: Cell Division Mitosis

Which of the following statements describes a characteristic feature of metaphase?

Alignment of chromosomes on the equator of the cell

Which of the following cellular events occur in the G1 phase of the cell division cycle?

Normal growth and cell function

Which of the following statements best describes how cytokinesis offers between plant and animal cells?

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

Which of the following occurs during S phase?

Replication of the DNA

The mitotic spindle plays a critical role in which of the following processes?

Separation of sister chromatids

Movement of the chromosomes during anaphase would be directly affected by a drug that prevents which of the following events?

Shortening of microtubules

Telophase

Spindle microtubules disassemble.

The _________ are the organizing center for microtubules involved in separating chromosomes during mitosis.

centrosomes

During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called _________.

chromatin

Cell A has half as much DNA as cells B, C, and D in a meiotically active tissue. Cell A is most likely in...

...G1

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...

...a plant cell in the process of cytokinesis.

Centromeres divide and sister chromatids become full-fledged chromosomes during...

...anaphase During anaphase, sister chromatids separate and daughter chromosomes migrate to opposite poles.

One difference between cancer cells and normal cells is that cancer cells...

...continue to divide even when they are tightly packed together.

Nucleoli are present during...

...interphase

Spindle fibers attach to kinetochores during...

...prometaphase Attachment of spindle fibers to kinetochores is one of the events of prometaphase.

Chromosomes become visible during...

...prophase During prophase, the chromatin fibers become discrete chromosomes.

After DNA replication, each duplicated chromosome consists of two...

...sister chromatids

Cytokinesis often, but not always, accompanies..

...telophase

If there are 24 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?

12

Which of the following properties is associated with a cyclin-dependent kinase (cdk)?

A cdk is an enzyme that attaches phosphate groups to other proteins.

Which of the following statements best describes a cleavage furrow?

A groove in the plasma membrane between daughter nuclei.

What is the name of the region on duplicated chromosomes where the sister chromatids are most closely attached to each other?

Centromere

What is the name of the microtubule-organized center found in animal cells as an identifiable structure present during all phases of the cell cycle?

Centrosome

Cytochalasin B is a chemical that disrupts microfilament formation. Which with aspect of cell division would cytochalasin B interfere?

Cleavage In animal cells, the cleavage furrow forms when a ring of microfilaments contracts, causing the parent cell to be pinched in two.

Anaphase

Cohesion breaks down. Kinetochores move toward pols of cell.

Prophase

Cohesion join sister chromatids of duplicated chromosome. Tubulins assemble into spindle miciritubules.

Which of the following molecules is synthesized at specific times during the cell cycle and forms an active complex with a kinase?

Cyclin

Eukaryotic chromatin is composed of which of the following macromolecules?

DNA and proteins

Telophase

Daughter nuclei are forming. Cytokinesis has started: The cell plate, which will divide the cytoplasm in two, is growing toward the perimeter of the parent cell.

Prometaphase

Discree chromosomes are now visible each consists of two aligned, identical sister chromatids. Later the nuclear envelope will fragment.

Which statement provides the best description of the interphase portion of the cell cycle?

During interphase, a cell is metabolically active. Interphase accounts for about 90% of the cell cycle and includes many key events critical to the cell cycle. It is not a resting stage; the cell is metabolically active during this phase.

Which of these phases encompasses all of the stages of mitosis but no other events?

E

If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct?

Each chromosome is made of a complex DNA and associated proteins. Eukaryotic nucleus contains chromatin, a complex of DNA and associated protein molecules. The proteins maintain the structure of the chromosomes and help control gene activity.

Which of the following events characterizes the beginning of anaphase?

Enzymatic cleavage of cohesion

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?

G1 In mammalian cells, this checkpoint is terminal the restriction point.

Which of the following correctly matches a phase of the cell cycle with its description?

G1, follows cell division. After mitosis and cytokinesis, the newly formed daughter cells enter the G1 phase.

Amount of DNA per nucleus over the cell division cycle. G1 is represented by which numbered part(s) of the cell division cycle in the accompanying figure?

I and V

Amount go DNA per nucleus over the cell division cycle. Which region of the accompanying figure represents S phase?

II

Amount of DNA per nucleus over the cell division cycle. Which numbered regions of the accompanying figure represents the DNA consent associated with cells at metaphase?

III

Students in a biology lab isolated cells in various pass of the cell cycle. A population of cells that have 1 1/2 times the DNA of G1 phase cells was most likely isolated from which of the following parts of the cell cycle?

In the S phase

Why is it difficult to observe individual chromosomes with a light microscope during interphase?

Interphase chromosomes are long, thin strands unlike the condensed chromosomes visible in mitosis. Except during the M phase, the DNA is extended, allowing its genes to be transcribed for protein synthesis.

Metaphase

Kinetochores are motionless in relation to poles of cell.

Prometaphase

Microtubules attach to kinetochores.

Which of the following statements best describes cells in culture that do not exhibit either density-dependent inhibition or anchorage dependence?

The cells show characteristics of tumors.

Anaphase

The chromatids of each chromosome have separated, and the daughter chromosomes are moving to the ends of the cell as their kinetochore microtubules shorten.

Prophase

The chromosomes are condensing and the nucleolus is beginning to disappear. The mitotic spindle is starting to form.

Metaphase

The spindle is complete, and the chromosomes, attached to microtubules at their kinetochores, are all at the plate.

Which of the following statements describing kinetochores is correct?

They are sites at which microtubules attach to chromosomes. As the spindle depolymerizes, the kinetochores appear to move along the spindle fiber, dragging the attached chromosomes with them.

Which of the following molecules is maintained at a relatively constant level throughout the cell cycle but requires a cycling to become catalytically active?

cdk

After chromosomes condense, the __________ is the region where the identical DNA molecules are most tightly attached to each other.

centromere

In most eukaryotes, division of the nucleus is followed by _________, when the rest of the cell divides.

cytokinesis

During telophase, the nonkinetochore microtubules ________.

disassemble

During _______ the cell grows and replicated both its organelles and its chromosomes.

interphase

In dividing cells, osteoporosis of the cell's growth occurs during ________.

interphase

During mitosis, microtubules attach to chromosomes at the ________.

kinetochores

During prophase, the microtubules of the mitotic spindle __________.

lengthen

During anaphase, the nonkinetochore microtubules ________ and move past each other, and the kinetochore microtubules ________.

lengthen; shorten

The ___________ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.

mitotic spindle

Will the chromosomes move to the poles of the cell?

no The inhibitor does not affect the cleavage of cohesins (the proteins that hold the sister chromatids together), the attachment of the chromosomes to the kinetochore microtubules, or the elongation of the cell due to the nonkinetochore microtubules. The inhibitor only affects the motor protein that pulls the chromosome along the kinetochore microtubule in anaphase. Thus, in the treated cell, the sister chromatids can still separate at the beginning of anaphase due to the fact that the cell is elongating (the centrosomes at the poles of the cell are moving farther apart) and the kinetochore microtubules still connect the chromosomes to the centrosomes. However, because the chromosomes cannot move along the kinetochore microtubules, they will never reach the poles of the cell.

DNA replication produces two identical DNA molecules, called ___________, which separate during mitosis.

sister chromatids

During _______ both the contents of the nucleus and the cytoplasm are divided.

the mitotic phase

Will the sister chromatids separate from each other?

yes The inhibitor does not affect the cleavage of cohesins (the proteins that hold the sister chromatids together), the attachment of the chromosomes to the kinetochore microtubules, or the elongation of the cell due to the nonkinetochore microtubules. The inhibitor only affects the motor protein that pulls the chromosome along the kinetochore microtubule in anaphase. Thus, in the treated cell, the sister chromatids can still separate at the beginning of anaphase due to the fact that the cell is elongating (the centrosomes at the poles of the cell are moving farther apart) and the kinetochore microtubules still connect the chromosomes to the centrosomes. However, because the chromosomes cannot move along the kinetochore microtubules, they will never reach the poles of the cell.

Will this cell elongated during mitosis?

yes The inhibitor does not affect the cleavage of cohesins (the proteins that hold the sister chromatids together), the attachment of the chromosomes to the kinetochore microtubules, or the elongation of the cell due to the nonkinetochore microtubules. The inhibitor only affects the motor protein that pulls the chromosome along the kinetochore microtubule in anaphase. Thus, in the treated cell, the sister chromatids can still separate at the beginning of anaphase due to the fact that the cell is elongating (the centrosomes at the poles of the cell are moving farther apart) and the kinetochore microtubules still connect the chromosomes to the centrosomes. However, because the chromosomes cannot move along the kinetochore microtubules, they will never reach the poles of the cell.