All of the following statements are true except:
The motic spindles in prokaryotic cells are composed of microtubules
The centromere is a region in which
Chromatids are attached to one another
Two centromeres are arranged at opposite poles of the cell
Centrioles begin to move apart in animal cells.
This is longest of the mitotic stages.
Centromeres uncouple, sister chromatids are seperated, and the two new chromosomes move to opposite poles of the cell
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested?
A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei containing how many chromosomes?
All of the following occur during prometaphase of mitosis in animal cells except
Chromosomes are duplicated
If there are 20 centromeress in a cell, how many chromosomes are there?
Of the following, the best conclusion concerning the difference between the S phase for beta and grama is that
gamma contains more DNA than beta
The best conclusion concering delta is that the cells
Containonly one chromosomethat is very short
The S phase was measured by
determining the start and stop of increased DNA in the cells
Where do the microtubules of the spindle orginate during mitosis in both plant and animal cells?
All of the following occur during mitosis except
The synthesis of DNA
if a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have during anaphase?
Cytokinesis usually, but not always, follows mitosis. If a cell composed mitosis but not cytokinesis, what would be the result?
a cell with 2 nuclei
reguarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants
a cell plate begins to form at telophase, whereas in animals a clevage furrow is initiated at that stage
How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?
the daughter cells have the same number of chromosomes and the same amount of DNA
The formation of a cell plate is beginning across the middle of a cell and nuclei are re-forming at opposite ends of the cell. What kind of cell is that?
a plant cell unergoing cytokinesis
Taxol is an anticancer drug extracted from the pacific yew tree. In animal cells, taxol disrupts mictrotubles and acclerating their assembly from the protein precursor, tubulin. Suprisingly this stops mitosis. Specifically taxol must affect
The fibers of the mitotic spindle
Which of the following is primarily responsible for cytokinesis in plant cells?
Golgi- derived vesicles
Which of the following organisms does not reproduce cells by mitosis and cytokinesis?
During which phase of mitosis do we find chromosomes composed of 2 chromatids?
from G2 of interphase through metaphase
Which of the following is not true of bacterial chromosome?
Its centromeres uncouple during replication
I which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis?
dinoflagellates and diatoms
Movement of the chromosomes during anaphase would be most affected by a drug that
Prevented shortening of microtubles
If mammalian cells recieve a go-ahead signal at the G1 checkpoint, they will
complete the cycle and divide
Cells that are in a nonividing state are in which phase?
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 was the nucleus with 6 picograms of DNA?
What causes the rhythmic change in cyclin concentration in the cell cycle?
Its destruction by an enzyme phosphorylated by MPF
released by platelets in the vicinity of an injury
enzymes that activate or inactivate other proteins by phosphorylating them
fibroblasts have receptors fro this substance on their plasma membranes
a protein synthesized through the cell cycle that associates with a kiase to form active enzymes
triggers the cell's passage past the G2 checkpoint into mitosis
the "restriction point" occurs here
nerve and muscle cells are in this phase
the shortest part of cell cycle
DNA is replicated at this time of the cell cycle
Cyclin is destroyed toward the end of this phase
What are enzymes called that control the activites of other proteins by phosphorylating them?
a group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. THose cells woul have ____ picograms at the end of the S phase and ________ picograms at the end of G2
16 ... 16
As the cell progresses through prophase and into metaphase, ehat happens to the active anaphase-promoting complex proteins?
they increase sharply once all the chromosomes are lined up in metaphase
what triggers the seperation of chromatids during mitosis?
activation of an anaphase-promoting complex
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called
THe MPF protein complex turns itself off by
activating an enzyme that destroys cyclin
recent research has indicated that cancer cells
transform normal cells by altering genes involved in the control of mitosis
a mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation?
the cell would undergo normal mitosis, but fail to enter the next G1
Density-dependent inhibition is explained by which of the following?
as the cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth
Which of the following is true concering cancer cells?
they do not exhibit density-dependent inhibition when growing in culture,when they stop dividing they do so at random points in the cell cycle, and they have escaped from cell cycle controls