Biology Chapter 12 Review

Which of the following structures or molecules is required in order for motor proteins to facilitate movement of chromosomes toward the poles in mitosis?

ATP as an energy source

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

Cdk

What is the best description of the structure of a chromosome in the nucleus of a non-dividing cell?

One long DNA molecule, associated with many proteins

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

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

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

centrosome

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol prevents microtubule depolymerization, which interferes with which of the following processes?

chromosome separation

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

cleavage

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

cleavage furrow formation and cytokinesis

Which of the following events characterizes the beginning of anaphase?

enzymatic cleavage of cohesion

1. Bacteria only 2. Eukaryotes only 3. Both bacteria and eukaryotes

1. Chromosome separation begins at the origin of replication of DNA 2. Nuclear envelope fragments, permitting chromosome separation; Two copes of the duplicated chromosome are attached at their centromeres before separating; before separation, duplicated chromosomes condense. 3. Chromosomes replicate before cell division. Replicated chromosomes separate by attaching to some other structural feature of the cell.

1. Which of these phases encompasses all of the stages of mitosis but no other events? 2. During ___ both the contents of the nucleus and the cytoplasm are divided. 3. During ____ the cell grows and replicates both its organelles and its chromosomes.

1. E 2. the mitotic phase 3. interphase

1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase

1. Tubulins assemble into spindle microtubules. Cohesion join sister chromatids of duplicated chromosome. 2. Microtubules attach to kinetochores. 3. Kinetochores are motionless in relation to poles of cell. 4. Kinetochores move toward poles of cell. Cohesion break down. 5. Spindle microtubules disassemble.

1. Which of these is NOT a carcinogen? 2. ____ is a carcinogen that promotes colon cancer.

1. all of the above are carcinogens 2. fat

1. Nucleoli are present during ____. 2. Cytokinesis often, but not always, accompanies ____. 3. Chromosomes become visible during ____. 4. Centromeres divide and sister chromatids become full-fledged chromosomes during ____. 5. Spindle fibers attach to kinetochores during ____.

1. interphase 2. telophase 3. prophase 4. anaphase 5. prometaphase

1. During prophase, the microtubules of the mitotic spindle ____. 2. During anaphase, the non kinetochore microtubules ____ and move past each other, and the kinetochore microtubules ____. 3. During telophase, the nonkinetochore microtubules ____.

1. lengthen 2. lengthen; shorten 3. disassemble

1. DNA replication produces two identical DNA molecules, called ____, which separate during mitosis. 2. After chromosomes condense, the ____ is the region where the identical DNA molecules are most tightly attached to each other. 3. During mitosis, microtubules attach to chromosomes at the ____. 4. In dividing cells, most of the cell's growth occurs during ____. 5. The ____ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division. 6. During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called ____. 7. In most eukaryotes, division of the nucleus is followed by _____, when the rest of the cell divides. 8. The ___ are the organizing centers for microtubules involved in separating chromosomes during mitosis.

1. sister chromatid(s) 2. centromere(s) 3. kinetochore(s) 4. interphase 5.mitotic spindle(s) 6. chromatin 7. cytokinesis 8. centrosome(s)

A human bone marrow cell, in prophase of mitosis, contain 46 chromosomes. How many chromatids does it contain?

92

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

A Cdk is an enzyme that attached phosphate groups to other proteins

How can a protein outside the cell cause events to happen inside the cell?

A protein outside the cell can bind to a receptor protein on the cell surface, causing it to change shape and sending a signal inside the cell.

Which of the following statements best describes density-dependent inhibition?

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

1. Cells divide by constriction of a ring of protein. 2. The presence of a cell wall prevents the cell from dividing by constriction. 3. Tubulin or tubulin-like molecules function in binary fission or cytokinesis.

Bacteria: true Animals: true Plants: false Bacteria: false Animals: false Plants: true Bacteria: true Animals: false Plants: true

How do cancer cells differ from normal cells?

Cancer cells may be immortal.

Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. Which of the following best explains the association between malignant tumors and chromosomal abnormalities?

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

Certain unicellular eukaryotes, including diatoms and some yeasts, have mechanisms of nuclear division that resemble intermediate steps in the evolution of mitosis. Which of the following is a characteristic feature of nuclear division in these organisms?

Chromosomes are segregated by a mitotic spindle, but the nuclear envelope remains intact during division

Eukaryotic chromatin is composed of which of the following macromolecules?

DNA nad proteins

Which statements provides the best description of the interphase portion of the cell cyle?

During interphase, a cell is metabolically active.

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 of DNA and associated proteins.

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

G1

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

G1

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

G1, follows cell division

Are sister chromatids present in all or part of this phase? Is the DNA condensed in all or part of this phase? Does the cell contain twice as much DNA in this phase as it did in the G1 phase?

G1: no S: yes G2: yes Beginning of M (prophase to early anaphase): yes End of N (late anaphase to telophase): no G1: no S: no G2: no Beginning of M: yes End of M: yes G1: no S: yes G2: yes Beginning of M: yes End of M: yes

The cell cycle controls systems of cancer cells differ from those of normal cells. Select the best explanation for this fact?

Genetic changes alter the function of the cancer cell's protein products.

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

Which chromosomal configuration would be observed at prometaphase of mitosis?

II

Which region of the accompanying figure represents S phase?

II

At which point in the accompanying figure does MPF reach its highest activity during the cell division cycle?

III

Which numbered regions of the accompanying figure represent the DNA content associated with cells at metaphase?

III only

A research team used a culture of lymphocytes with radioactively labeled T nucleotides to study the cell cycle. They found that the lymphocytes incorporated the labeled nucleotide at a significantly higher rate after a pathogen was introduced into the culture. Which of the following conclusions is most consistent with the results?

Infection causes lymphocytes to divide more rapidly

Progression beyond the G2 checkpoint into mitosis is triggered by which of the following molecules?

MPF

Which of the following best describes microtubules?

Microtubules are made up of subunits of tubulin, and are structures along which substances are transported in the cell.

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

Which of the following statements best describes what happens to MPF during mitosis?

The cyclin component of MPF is degraded

Exposure of zebrafish nuclei to cytosol isolated from eggs at metaphase of mitosis 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?

They are involved in the disassembly of the nuclear envelope.

Which of the following statements best explains how neurons and some other specialized cells divide infrequently?

They have entered into G0.

What is true of a call cancers?

They have escaped normal cell cycle controls.

Which chromosomal configuration would be observed in one daughter cell after telophase of mitosis?

V

Which of the following statements are true of cytokinesis in plant cells?

Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate. The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells.

Which of the following statements best describes a cleavage furrow?

a groove in the plasma membrane between daughter nuclei.

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

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

a. G1 b. G1 checkpoint c. S d.G2 e. After G2 checkpoint, in prophase f. Cytokinesis

a. Non dividing cells exit cell cycle. b. At this point, cell commits to go through the cycle. c. DNA replicates d. Two centrosomes have formed. e. Mitotic spindle begins to form. f. Cell divides, forming two daughter cells.

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

alignment of chromosomes on the equator of the cell

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in ____

cells with more than one nucleus.

The drug cytochalasin B blocks the polymerization of actin microfilaments. Which of the following events of the cell cycle in animal cells would be most directly disrupted by cytochalasin B?

cleavage furrow formation and cytokinesis

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

continue to divide even when they are tightly packed together.

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

cyclin

Which of the following pairs of molecules make up an active MPF?

cyclin and a cyclin-dependent kinase

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to ____

disruption of mitotic spindle formation

Which of the following occurs in binary fission but not in mitosis with cytokinesis?

duplicated chromosomes attach to the plasma membrane.

At what stage of the cell cycle is the cyclin component of MPF destroyed?

in late M

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

Which of the following characteristics would be most important for a chemotherapeutic drug designed to treat cancer cells?

it specifically inhibits the cell division cycle in rapidly dividing cells

Besides the ability of some cancer cells to over proliferate, which of the following situations is most likely to result in a tumor?

lack of appropriate cell death

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?

large cells containing many nuclei

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

normal growth and cell function

At which phase of the cell cycle do centrioles begin to move apart in animal cells?

prophase

Which of the following events would be most likely to produce cells with several nuclei?

repeated mitosis without cytokinesis.

Which of the following events occurs during interphase of the cell cycle?

replication of the DNA

Which of the following occurs during S phase?

replication of the DNA

If the cell whose nuclear material is shown in the accompanying figure continues toward completion of mitosis, which of the following events would occur next?

segregation of daughter chromosomes

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 most directly affected by a drug that prevents which of the following events?

shortening of microtubules

Which of the following statements best describes what would happen if MPF (maturation-promoting factor) is introduced into immature frog oocytes that are arrested in G2?

the cells would enter mitosis

FtsZ is a bacterial protein that forms a contractile ring involved in binary fission. Its function is analogous to which of the following structures in eukaryotic cells?

the cleavage furrow of eukaryotic animals cells

The decline of MPF activity at the end of mitosis is due to ____.

the degradation of cyclin

Which of the following statements describing kinetochores is correct?

they are sites at which microtubules attach to chromosomes.

Which of the following is true of benign tumors, but not malignant tumors?

they remain confined to their original site