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Nucleoli are present during _____. |
interphase -Nucleoli are present during interphase |
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Cytokinesis often, but not always, accompanies _____. |
telophase -Cytokinesis often, but not always accompanies telophase. |
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Chromosomes become visible during _____. |
Prophase -During prophase, the chromatin fibers become discrete chromosomes. |
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Centromeres divide and sister chromatids become full-fledged chromosomes during _____. |
anaphase -During anaphase, sister chromatids separate and daughter chromosomes migrate to opposite poles. |
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Spindle fibers attach to kinetochores during _____. |
prometaphase -attachment of spindle fibers to kinetochores is one of the events of prometaphase |
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During prophase a homologous pair of chromosomes consists of _____. |
two chromosomes and four chromatids. -at this point each of the chromosomes consists of two chromatids. |
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During _____ both the contents of the nucleus and the cytoplasm are divided |
the mitotic phase -the mitotic phase encompasses both mitosis and cytokinesis |
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During _____ the cell grows and replicates both its organelles and its chromosomes. |
interphase -these are the events of interphase |
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Which event does not take place before the start of mitosis? |
The nuclear envelope disintegrates -this event takes place during mitosis |
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True of False? Mitosis takes place during M phase, which is the longest phase of the cell cycle. |
False -Mitosis does indeed take place during M phase, but M phase is the shortest phase of the cell cycle. |
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Which term describes two recently replicated DNA strands that are joined together just before cell division? |
Sister chromatids -Sister chromatids are the two strands of a recently replicated chromosome that will be split apart during cell division. |
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During which stage of mitosis are chromosomes lined up in the center of the cell? |
Metaphase -Chromosomes held by spindle fibers are lined up in the middle of the cell during metaphase, the third and middle stage of mitosis |
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Which stage of mitosis is characterized by the disintegration of mitotic spindles and the formation of two new nuclear membranes? |
Telophase -the mitotic spindles disintegrate and a nuclear envelope begins to form around each set of chromosomes during telophase, the last substage of mitosis |
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To which part of the centromere do mitotic spindle fibers attatch during prometaphase? |
Kinetochore -The kinetochore is the region of the centromere on the sister chromatid to which the mitotic spindle attaches. |
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During which substage of mitosis do sister chromatids break apart and start moving to opposite poles of the cell? |
Anaphase -Chromatids are pulled to opposite poles of the cell during anaphase, the fourth substage of mitosis |
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Which of these is NOT a carcinogen? |
cigarette smoke, fat, UV light, testosterone, all of the above are carcinogens -all of these substances can cause cancer |
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___ is a carcinogen that promotes colon cancer |
fat -a diet high in fat increases the risk of both colon and breast cancer |
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Which of the following is a function of the S phase in the cell cycle? |
The synthesis of sister chromatids -DNA replication occurs during S phase and results in two sister chromatids for each original chromosome |
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The copying of chromosomes occurs during which of the following phrases of the cell cycle? |
S phase -Chromosomes must undergo replication before mitosis can occur; this copying occurs during the S phase |
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For the first several divisions of early frog embryos, cells proceed directly from the M phase to the S phase and back to M without gaps. Which of the following is likely to be true about dividing cells in early frog embryos? |
The cells get smaller with each generation. -Without gap phases, the cells have no opportunity to grow |
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True of false? The M phase is characterized by the replication and division of a cell’s chromosomes |
True -Correct: Cells replicate their chromosomes during the S phase and divide partition their chromosomes during the M phase |
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If an organism normally has 34 chromosomes, how many molecules of DNA should there be in the G1 phase of the cell cycle? |
34 -There is one DNA molecule per chromosome |
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Which of the following events would cause the cell cycle to arrest? |
Poor nutrient conditions -Poor nutrient conditions would arrest the cell cycle at the G1 checkpoint. |
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