Chapter 12- The Cell Cycle

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

G1: follows cell division

Since 1991, deaths from breast and colorectal cancer in the United States are down 35%. What is the main reason for this?

better screening

Metaphase

Kinetochores are motionless in relation to poles of cell.

Anaphase

Kinetochores move toward poles of cell. Cohesins break down.

Which region shows the population of cells with the highest amount of DNA per cell?

Region C

What does the difference in distribution tell you about the cells in the treated sample?

The treated cancer cells are arrested at the G1 phase.

Which statement best describes the difference(s) in the distribution of cells in the treated sample compared to the control sample?

The treated cells are mostly in the G1 phase (region A), but in the control sample, there are peaks of cells in both G1 and G2 (region C).

What treatment is being compared to the control in the experiment?

The treated glioblastoma cells were cultured in the presence of an inhibitor from umbilical cord stem cells, but the control cells were cultured without the inhibitor.

Which axis indirectly shows the relative amount of DNA per cell? By what relationship?

The x-axis; the DNA was stained, so there is a positive correlation between fluorescence and DNA content.

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

mitotic spindle(s)

3. Will the chromosomes move to the poles of the cell?

no

Can you match these prefixes, suffixes, and word roots with their definitions?

one: uni- before: pro- cell: -cyte (or cyto-) moving: kin- (or kinet-) thread: mito- segment, body section: -mere many: multi- between: inter- end: telo- two: bi-

Which of the following organisms would be most similar to humans in a study that involved the response of cancer cells to various medications?

primates

Which of the following is closest to the current average annual death rate from cancer in the United States?

580 thousand

Cytokinesis in animal cells is accomplished by constriction of the cell along the plane of cell division (formation of a cleavage furrow). In plant cells, which have cell walls, a completely different mechanism of cytokinesis has evolved. Which of the following statements are true of cytokinesis in plant cells? Select the two that apply.

-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

Plant and animal cells also require cytoskeletal proteins for cytokinesis, although the roles these proteins play differ among bacteria, plants, and animals. For each space in the table, drag the appropriate label to indicate if the statement is true or false for each group of organisms.

1. Bacteria: true Animals: true Plants: false 2 bacteria: false Animals: false Plants: true 3. Bacteria: true Animals: false Plants: true

When did the United States declare a "war on cancer" by passing the National Cancer Act?

1971

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

92

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

During interphase, a cell is metabolically active.

As the chromosomes of a parent cell are duplicated and distributed to the two daughter cells during cell division, the structure of the chromosomes changes.Answer the three questions for each phase of the cell cycle by dragging the yes and no labels to the appropriate locations in the table.Note: Assume that by the end of the M phase, the parent cell has not yet divided to form two daughter cells.

Are sister chromatid present in all or part of this phase? G1-no S-yes G2-yes Beginning of M-yes End of M-no Is the DNA condensed in all or part of this phase? G1- no S-no G2-no Beginning of M-yes End of M-yes 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- yes End of M-yes

In all cells, separation of replicated chromosomes is a prerequisite for cell division. However, the mechanism of chromosome separation in bacteria is distinct from that in eukaryotes in several ways. Sort the following statements into the appropriate bin.

Bacteria only: chromosome separation begins at the origin of replication on DNA Eukaryotes only: Before separation duplicated chromosomes condense; nuclear envelope fragments permitting chromosome separation; two copies of the duplicated chromosome are attached at their centromeres before separating Both Bactria and eukaryotes: chromosomes replicate before cell division; replicated chromosomes separate by attaching to some other structural feature of the cell

How do cancer cells differ from normal cells?

Cancer cells may be immortal.

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

E- mitosis

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.

Which of the following best describes the advantages of the personalized care technique described in the video?

Fruit flies make excellent models because we can create a strain of flies with a specific type of tumor, then raise thousands of flies in order to test the effects of medications.

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question 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

The cell cycle control 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.

prometaphase

Microtubules attach to kinetochores.

In the control sample histogram, does the population of cells in the S phase show a distinct peak? Why or why not?

No; the DNA content per cell changes as the S phase progresses, so the cells in S phase have a range of fluorescence levels.

Telophase

Spindle microtubules disassemble.

Which mechanism is the best explanation for how the stem cell-derived inhibitor might arrest the cancer cell cycle at the G1 stage?

The inhibitor might block the activity of a cyclin or signaling molecule of the G1 checkpoint.

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

The mitotic phase encompasses both mitosis and cytokinesis.

Which of the following is true of kinetochores?

They are sites at which microtubules attach to chromosomes.

What is true of all cancers?

They have escaped normal cell cycle controls.

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

They have uncoiled to form long, thin strands.

Why do some species employ both mitosis and meiosis, whereas other species use only mitosis?

They need both if they are producing animal gametes.

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

They remain confined to their original site

Prophase

Tubulins assemble into spindle microtubules. Cohesins join sister chromatids of duplicated chromosome

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.

The cell cycle represents the coordinated sequence of events in the life of a cell from its formation to its division into two daughter cells. Most of the key events of the cell cycle are restricted to a specific time within the cycle. In this exercise, you will identify when various events occur during the cell cycle. Recall that interphase consists of the G1, S, and G2 subphases, and that the M phase consists of mitosis and cytokinesis.

a. non-dividing cells exit cell cycle b. at this point, cell commits to go through the cycle c. DNA replicate d. 2 centrosomes have formed e. mitotic spindle begins to form f. cell divides, forming two daughter cells

Which of these is NOT a carcinogen?

all of the above are carcinogens

Based on the information in the video, which of the following correctly answers these three questions:What was the leading cause of death in the United States in the early 1970s?What is the leading cause of death in the United States today?What is predicted to be the leading cause of death in the United States 10 years from now?

cancer; cardiovascular disease; cancer

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

cells with more than one nucleus.

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

centromere(s)

The BLANK are the organizing centers for microtubules involved in separating chromosomes during mitosis

centrosome(s)

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

chromatin

Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division?

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

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

continue to divide even when they are tightly packed together.

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

cytokinesis

3. During telophase, the nonkinetochore microtubules

disassemble

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.

_____ is a carcinogen that promotes colon cancer.

fat

During _____ the cell grows and replicates both its organelles and its chromosomes.

interphase

In dividing cells, most of the cell's growth occurs during BLANK

interphase

During mitosis, microtubules attach to chromosomes at the

kinetochore(s)

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

1. During prophase, the microtubules of the mitotic spindle

lengthen

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

lengthen and shorten

Identify which phase of the cell cycle is represented by each region. The regions represent the same cell cycle phases in both histograms.

region A: G1 region B: S region C: G2

Can you match these prefixes, suffixes, and word roots with their definitions?

self: auto- small: micro- chromosomes: ploid body: -some (or soma-) both, double: diplo- without, lack of, not: a- (or an-) color: chrom- single: haplo- to produce: -gen- same: homo- (or homeo-)

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

sister chromatids

In the treated sample histogram, which phase of the cell cycle has the greatest number of cells?

the G1 phase

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

the degradation of cyclin.

Why is the "personalized care" plan described in the video, in which treatments are tailored for each individual, much more promising than previous treatment plans?

the genetic mutations that cause cancer vary from patient to patient

1. Will this cell elongate during mitosis?

yes

2. Will the sister chromatids separate from each other?

yes