chapter 12 mastering bilogy

Which of these phases encompasses all of the stages of mitosis but no other events? C A B E D

e mitosis

Part C - Changes in DNA structure during the cell cycleAs 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.

1. yes, yes, yes, no 2. no, no, yes, yes 3. yes, yes, yes, yes

In a diploid cell with 5 chromosome pairs (2n = 10), how many sister chromatids will be found in a nucleus at prophase of mitosis? 20 40 5 10

20

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? See Concept 12.1 (Page 236 23 92 23 or 46, depending on the portion of prophase examined 46 46 or 92, depending on the portion of prophase examined

92

Part B - Phases of the cell cycleThe 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.Drag each label to the appropriate target.

A) Non- dividing cells exit cell cycle B) At this point, cell commits to go through the cell cycle C) DNA replicates D) Centrosome replicates E) Mitotic spindle begins to fromF) Cell divides, forming two daughter cells

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? See Concept 12.3 (Page 244) S G1 M cytokinesis G2

G1

Which of the following correctly matches a phase of the cell cycle with its description? See Concept 12.2 (Page 237) M: duplication of DNA G2: cell division G1: follows cell division S: immediately precedes cell division All of the above are correctly matched.

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

During which phase of mitosis do the chromatids become chromosomes? telophase metaphase prophase anaphase

anaphase

Centromeres divide and sister chromatids become full-fledged chromosomes during _____. telophase anaphase metaphase prometaphase nterphase

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

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

centromere(s)

The __________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 ________

chromatin

Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division? See Concept 12.2 (Page 237) binary fission formation of the mitotic spindle cleavage formation of the cell plate DNA replication

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

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

cytokinesis

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? S G2 G0 G1

g2

During _____ the cell grows and replicates both its organelles and its chromosomes. interphase mitosis G1 cytokinesis S

interphase

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

interphase

Nucleoli are present during _____. metaphase prophase interphase prometaphase anaphase

interphase Nucleoli are present during interphase

. During mitosis, microtubules attach to chromosomes at the ______

kinetichore(s)

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 ________. telophase prophase G2 metaphase

metaphase

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

miotic spindles

Spindle fibers attach to kinetochores during _____ anaphase interphase metaphase telophase prometaphase

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

Chromosomes become visible during _____. prophase interphase metaphase anaphase prometaphase

prophase

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

sister chromatids

Cytokinesis often, but not always, accompanies _____. prometaphase anaphase metaphase telophase interphase

telphase Cytokinesis often, but not always, accompanies telophase.

Once a cell enters mitosis, the molecules that activate division must be turned off. What happens to MPF during mitosis? The Cdk component of MPF is degraded. The cyclin component of MPF is degraded. It is phosphorylated by a Cdk, which inactivates it. It is completely degraded. Submit

the cyclin comments of MPFs is degraded

During _____ both the contents of the nucleus and the cytoplasm are divided. S G2 G1 mitosis the mitotic phase

the mitotic phase