Ch. 12 HW

Spindle fibers attach to kinetochores during _____.

prometaphase

In a diploid cell with four chromosome pairs (2n = 8), how many sister chromatids will be found in a nucleus at prophase of mitosis?

16

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

During interphase, a cell is metabolically active.

The mitotic spindle consists of two types of microtubules: kinetochore microtubules and nonkinetochore microtubules. In animal cells, these two types of microtubules function differently in the stages of mitosis. Complete the sentences by dragging the terms to the appropriate locations. Terms may be used once, more than once, or not at all.

During prophase, the microtubules of the mitotic spindle lengthen. During anaphase, the nonkinetochore microtubules lengthen and move past each other, and the kinetochore microtubules shorten. During telophase, the nonkinetochore microtubules disassemble.

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

E

Match each cell cycle phase to what happens in that phase.

G1: Cell growth and increase in energy production G0 : A cell's nondividing stage M : Cell growth stops and the cell divides S : DNA replication G2 : Cell growth and preparation for division

Nucleoli are present during _____.

Interphase

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

MPF

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.

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.

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

Which of the following statements describing kinetochores is correct?

They are sites at which microtubules attach to chromosomes.

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

cells with more than one nucleus.

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

prophase

Chromosomes become visible during _____.

prophase

Cytokinesis often, but not always, accompanies _____.

telophase

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

the degradation of cyclin.

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

the mitotic phase

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

V

Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division? See Concept 12.2 (Page)

cleavage

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

interphase

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

anaphase

The continuity of life depends on a cell cycle during which genetic information is passed from a parent cell to daughter cells. Because cell division plays several important roles in life, it is important that the cycle be regulated. Which of the following are reasons the cell cycle must be regulated? Select all that apply.

- To make sure cells only divide when conditions are favorable for growth and development of the organism -To allow cells to respond to cues from their internal state and from their environment -To make sure daughter cells end up with the right number of chromosomes

Consider an animal cell in which motor proteins in the kinetochores normally pull the chromosomes along the kinetochore microtubules during mitosis. Suppose, however, that during metaphase, this cell was treated with an inhibitor that blocks the function of the motor proteins in the kinetochore, but allows the kinetochore to remain attached to the spindle. The inhibitor has no effect on any other mitotic process, including the function of the nonkinetochore microtubules. Consider three questions concerning the animal cell that has been treated with the inhibitor. Drag the terms to answer the questions. Terms may be used once, more than once, or not at all.

1. Will this cell elongate during mitosis? Yes 2. Will the sister chromatids separate from each other? Yes 3. Will the chromosomes move to the poles of the cell? No

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? See Concept 12.1 (Page)

92

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

The M checkpoint is an example of a checkpoint that is internally controlled by the cell. What would be the potential consequence seen in daughter cells if the cell received a stop signal at this checkpoint but was able to continue to anaphase anyway?

At the completion of mitosis and cytokinesis, the daughter cells could have missing or extra chromosomes.

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

G1

What would be the consequence of a mutation in each tumor-suppressor gene? Drag one consequence to each bin.

Mutation in the p53 gene - Cell receives go-ahead signal at the G1 checkpoint and most likely finishes the cell cycle with damaged DNA. Mutation in the RB gene - Cell receives go-ahead signal at the G1 checkpoint, entering the S phase regardless of whether conditions are good for growth. Mutation in the MAD gene - Cell receives go-ahead signal at the M checkpoint and daughter cells may end up with extra or missing chromosomes.

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

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

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

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