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bio ch12
ch.12 ?'s
Question | Answer |
---|---|
The centromere is a region in which | chromatids remain attached to one another |
what is a chromatid? | a replicate chromosome |
starting with a fertilized egg(zygote), a series of 5 cell divisions would produce an early embryo with how many cells? | 32 |
if there are 20 chromatids in a cell, how many centromeres are there? | 10 |
for a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission? | cell division would allow for the orderly and efficient segregation of multiple linear chromosomes |
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 |
at prometaphase of mitosis | |
one daughter nucleus at telephase of mitosis | |
which term describes 2 centrosomes arranged at opposite poles of the cell? | promethaphase |
which term descibes centrioles beginning to move apart in animal cells? | prophase |
which is the longest of the mitosis stage? | metaphase |
which term describe centromere uncoupling, sister chromatids separating and the 2 new chromosomes moving to opposite poles of the cell? | anaphase |
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 | metaphase |
a cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce 2 nuclei each containing how many chromosomes? | 46 |
If the cell whose nuclear material continues toward completion of mitosis, which of the following events would occur next? | formation of telophase nuclei |
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? | 20 |
if there are 20 chromatids in a cell at metaphase, how many chromosomes are there in each daughter cell following cytokinesis? | 10 |
Of the following, the best conclusion concerning the difference between the S phased for beta and gamma is that.. | gamma contains more DNA than beta |
The best conclusion concerning delta is that the cells.. | are actually in the G0 phase |
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? | centrosome |
If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have dring anaphase? | 16 |
Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis the result would be a cell with | 2 nuclei |
Regarding mitosis and cytokinesis, 1 difference between higher plants and animals is that in plants | a cell plate begins to form at telophase whereas in animals a cleavage furrow is initiated at that stage |
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 this? | a plant undergoing cytokinesis |
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. This stops mitosis. Taxol affects.. | dinoflagellates the fibers of the mitotic spindle |
Which of the following are primarily responsible for cytokinesis in plant cells? | golgi-derived vesicles |
Chromosomes first become visible during which phase of mitosis? | prophase |
During which phases of mitosis are chromosomes composed of two chromatids? | from G2 of interphase through metaphase |
In 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 | prevents shortening of microtubules. |
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? | G2 |
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 would have __________ picograms at the end of the S phase and __________ picograms at the end of G2. | 16; 16 |
The somatic cells derived from a single-celled zygote divide by which process? | mitosis |
Imagine looking through a microscope at a squashed onion root tip. The chromosomes of many of the cells are plainly visible. Some cells, replicated chromos. are aligned along the equator of the cell. These particular cells are in which stage of mitosis? | metaphase |
In order for anaphase to begin, which of the following must occur? | Cohesin must be cleaved enzymatically |
Why do chromosomes coil during mitosis? | to allow the chromosomes to move without being entangled and breaking |
Which of the following is a function of those spindle microtubules that do not attach to kinetochores? | maintaining the region of overlap of fibers in the cell's center |
Nucleotides can be radiolabeled before incorporated into new DNA & can be assayed to track their incorporation. In experiments, a research team used labeled T nucleotides & introduced these into the culture of dividing human cells at specific times. | |
which question might be answered by this method? | What is the length of the S phase of the cell cycle? |
The research team used the setup to study the incorporp. of labeled nucleotides to a culture of lymphocytes & found that the lymphocytes incorporated the labeled nucleotide at a much higher level after pathogen was introduced to the culture & concluded: | infection causes lymphocytes to divide more rapidly |
If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will | complete the cycle and divide |
Cells that are in a nondividing state are in which phase? | G0 |
What causes the decrease in the amount of cyclin at a specific point in the cell cycle? | its destruction by a process initiated by the activity of its complex with a cyclin |
What is a general term for enzymes that activate or inactivate other proteins by phosphrylating them? | protein kinase |
What is released by platelets in the vincinity of an injury? | PDGF |
Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex? | cyclin |
Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active? | Cdk |
The shortest part if the cell cycle: | M |
DNA is replicated at this time of the cell cycle: | S |
G1 | |
What triggers the cell's passage past the G2 checkpoint into mitosis? | MPF |
The "restriction point" occurs here: | G1 |
Nerve and muscle cells are in this phase: | G0 |
The cyclin componenet of MPF is destroyed toward the end of this phase: | M |
In the figure above, mitosis is represented by which number? | 4 |
G1 is represented by which number? | 1 and 2 |
Which number represents DNA synthesis? | 2 |
Which number represents the point in the cell cycle during which the chromosomes are replicated? | 2 |
MPF reaches its threshold concentration at the end of this stage? | 3 |
An enzyme that attaches a phosphate group to another molecule is called a: | kinase |
Proteins that are involved in the regulation of the cell cycle, are called | cyclins |
MPF protein complex turns itself off by | activiating a process that destroys cyclin component |
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 results of this mutuation? | the cell would undergo normal mitosis, but fail to enter the next G1 phase |
Density-dependent inhibition is explained by which of the following? | As cells become more numberous, the cell surface protens of one cell contact the adjoining cells and they stop dividing |
Which of the following is true concerning cancer cells? | A,B,& C (all) |
Which of the following describe cyclin-dependent kinase(CDK)? | B and C (Cdk is present throught the cell cycle and is an enzyme that attatches phosphate groups to other proteins) |
A particular cyclin called cyclin E forms a complex with a Cyclin-dep. kinase called CDK 2. The complex is important for the progression of the cell from G1 into the S phase of the cell cycle. which is correct? | The amount of cyclin E is highest during G1 |
The research team establish similar lymphocyte cultures from a number of human donors...they repeated the study with a larger # of samples but got the same results. what might be a conclusion? | The elderly persons' samples demonstrated their lower immune response |
Cells from an advance malignant tumor most often have very abnormal chromosomes and often an abnormal total number of chromosomes. Why might this occur? | Chromosomally abnormal cells can still go through cell cycle checkpoints |
Besides the ability of some cancer cells to overproliterate, what else could logically result in a tumor? | lack of appropriate cell death |
Through a microscope, you can see a cell plate. This cell is most likely: | a plant cell in the process of cytokinesis |
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to | distribution of mitotic spindle formation |
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 |
One difference between cancer cells and normal cells is that cancer cells | continue to divide even when they are tightly packed together |
The decline of MPF activity at end of mitosis is due to | the degradation of cyclin |
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B? | cleavage furrow formation |
The cells of some organisms, mitosis occurs without cytokinesis. This will result in: | cells with more than one nucleus |
Which of the following does NOT occur during mitosis? | replication of the DNA |