12 13 biology Flashcards


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1

binary fusion ---A method of asexual reproduction by “division in half.” In prokaryotes, binary fission does not involve mitosis, but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process.

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2

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)an animal cell in the process of cytokinesis.

B)an animal cell in the S phase of the cell cycle.

C)a bacterial cell dividing.

D)a plant cell in the process of cytokinesis.

E)a plant cell in metaphase.

D)a plant cell in the process of cytokinesis.

3

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

myosin denaturation and inhibition of cleavage furrow formation.

suppression of cyclin production.

inhibition of regulatory protein phosphorylation.

disruption of mitotic spindle formation.

inhibition of DNA synthesis.

disruption of mitotic spindle formation.

4

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

continue to divide even when they are tightly packed together. are arrested at the S phase of the cell cycle. are always in the M phase of the cell cycle. cannot function properly because they are affected by density-dependent inhibition. are unable to synthesize DNA.

continue to divide even when they are tightly packed together.

5

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

decreased synthesis of Cdk. synthesis of DNA. the degradation of cyclin. the accumulation of cyclin. the destruction of the protein kinase Cdk.

the degradation of cyclin.

6

In the cells of some organisms, mitosis occurs without cytoki-nesis. This will result in

cells lacking nuclei. cells with more than one nucleus. destruction of chromosomes. cells that are unusually small. cell cycles lacking an S phase.

cells with more than one nucleus.

7

Which of the following does not occur during mitosis?

--condensation of the chromosomes

--replication of the DNA

--separation of sister chromatids

--spindle formation

--separation of the spindle poles

replication of the DNA

8

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.

9

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

10

Assume that you are dealing with species in which the number of chromosomes in each somatic cell is 14. How many sister chromatids are present in early telophase of mitosis

A)28 C)7

B) 14 D)0

D) 0

IN THIS CASE, MITOSIS STARTS WITH 14 CHROMOSOMES, EACH OF WHICH CONSISTS OF 2 CHROMATIDS, BECAUSE THE CELL HAS BEEN S PHASE.BY TELOPHASE, THE CHROMATIDS HAVE SEPARATED AND INDIVIDUAL UNITS OF DNA (NOW CALLED CHROMOSOMES) ARE ARRIVING AT THE POLES.THERE ARE NO CHROMATIDS AT THIS POINT.

11

DNA replication occurs in _____

S phase of interphase of both somatic and reproductive cells

12

when a cell in S phase is fused with a cell in G1

A) chromosomes of original G1 nucleus condense in preparation for mitosis

B) DNA begins immediately in the original G1 nucleus

C) The original G1 cell will divide immediately

D) two nuclei fuse and further division is arrested

B) DNA begins immediately in the original G1 nucleus

this observation indicates that cytoplasmic signals can participate in the regulation of the cell cycle

13

! During interphase the chromatin cannot be seen and the spindle has not yet begun to form

! During prophase, we observe the formation of the spindle, the condensation of chromatin, the disappearance of the nucleus

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14

! During prophase mitotic spindle begins to form

! Mitosis, the division of the nucleus, is usually followed immediately by cytokinesis, the division of the cytoplasm.

! Mitotic spindle---An assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis.

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15
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Prokaryotes reproduce by the type of cell division called binary fission, which involves replicating the single chromosome and distributing copies equally to two daughter cells

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16

between anaphase and telophase sister chromatids are separated to the opposite poles of the cell and recognized into new nuclei

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17

a cell biologist carefully measures the quantity of DNA in grasshopper cells growing in cell culture.Cells examined during the G2

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18

Which of the following does not occur during mitosis

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