Mastering Biology Chapter 12

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

sister chromatid(s)

Cohesins break down

Anaphase

Kinetochores move toward poles of cell

Anaphase

Consider a question concerning an animal cell that has been treated with an inhibitor: Will the chromosomes move to the poles of the cell?

No

Comparing chromosome separation in Eukaryotes and Bacteria: *Chromosome separation begins at the origin of replication on DNA *Before separation, duplicated chromosomes condense *Nuclear envelope fragments, permitting chromosome separation *Two copies of duplicated chromosome are attached at their centrosomeres before separation *Chromosomes replicated before cell division *Replicated chromosomes separate by attaching to some other structural feature of the cell

BACTERIA ONLY: *Chromosome sweparation 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 separation BOTH BACTERIA AND EUKARYOTES: *Chromosomes replicate before cell division *Replicated chromosomes separate by attaching to some other structural feature of the cell

The presence of a cell wall prevents the cell from dividing by constriction

Bacteria: FALSE Animals: FALSE Plants: TRUE

Tubulin or tubulin-like molecules function in binary fission (in bacteria) or cytokinesis (In animals and plants)

Bacteria: TRUE Animals: FALSE Plants: TRUE

Cells divide by constriction of a ring of protein

Bacteria: TRUE Animals: TRUE Plants: FALSE

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

Centromeres

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? formation of the mitotic spindle formation of the cell plate DNA replication cleavage binary fission

Cleavage

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 mitosis, microtubules attach to chromosomes at the ____________.

Kinetochore(s)

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? M G1 cytokinesis S G2

G1

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

Kinetochores are motionless in relation to poles of cell

Metaphase

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

Mitotic spindle(s)

Microtubules attach to kinetochores

Prometaphase

Cohesins join sister chromatids of duplicated chromosome

Prophase

Tubulins assemble into spindle microtubules

Prophase

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. After chromosome separation is complete, a network of microfilaments forms near the plane of cell division that will separate the two new cells. The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells. The plasma membrane of the parent cell grows inward, eventually joining with the cell plate. 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 Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate

Spindle microtubules disassemble

Telophase

Why do some species employ both mitosis and meiosis, whereas other species use only mitosis? They need only mitosis to make large numbers of cells such as sperm. They need only meiosis if they produce egg cells. They need both if they are producing animal gametes. A single-celled organism only needs mitosis. They need meiosis if the cells are producing organs such as ovaries.

They need both if they are producing animal gametes

Consider a question concerning an animal cell that has been treated with an inhibitor: Will the cell elongate during mitosis?

Yes

Consider a question concerning an animal cell that has been treated with an inhibitor: Will the sister chromatids separate from each other?

Yes