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53 terms

Chapter 12

STUDY
PLAY
DNA replication produces two identical DNA molecules, called ________, which separate during mitosis.
Sister chromatids
After chromosomes condense, the _______ is the region where the identical DNA molecules are most tightly attached to each other.
Centromeres
During mitosis, microtubules attach to chromosomes at the ______.
Kinetochores
In dividing cells, most of the cell's growth occurs during what phase?
Interphase
The ____ ______ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.
Mitotic Spindles
During interphase, most of the nucleus is filled wit ha complex of DNA and protein in a dispersed form called _____.
Chromatin
In most eukaryotes, division of the nucleus is followed by _______, when the rest of the cell divides.
Cytokinesis
The _____ are the organizing centers for microtubules involved in separating chromosomes during mitosis.
Centrosomes
What is the first step in preparing for division?
Replication of DNA in the S phase.
What phase do the centrosomes replicate?
G2 phase
What main processes occur within prophase?
Tubulins assemble into spindle microtubules and the cohesins join sister chromatids of duplicated chromosome.
What main processes occur within prometaphase?
Microtubules attach to kinetochores.
What main processes occur within metaphase?
Kinetochores are motionless in relation to poles of cell.
What main processes occur within anaphase?
Cohesins break down and kinetochores move toward poles of cell.
What main processes occur within telophase?
Spindle microtubules disassemble.
What happens to the length of the mitotic spindles during prophase?
Lengthen
During anaphase, the nonkinetochore microtubules _______ and move past each other, and the kinetochore microtubules _______
Lengthen; shorten
During telophase, the nonkinetochore microtubules _________.
Disassemble
During _____ both the contents of the nucleus and the cytoplasm are divided.
The mitotic phase
During _____ the cell grows and replicates both its organelles and its chromosomes.
Interphase
Which of these are carcinogens?
UV light, cigarette smoke, testosterone, fat
_____ is a carcinogen that promotes colon cancer.
Fat
Nucleoli are present during which phase?
Interphase
Cytokinesis often, but not always, accompanies _____.
Telophase
Centromeres divide and sister chromatids become full-fledged chromosomes during _____.
Anaphase
Spindle fibers attach to kinetochores during _____.
Prometaphase
What happens during anaphase?
During anaphase centromeres come apart, and sister chromatids become full-fledged chromosomes, which migrate to opposite poles of the cell.
In animal cells, what forms before cytokinesis?
Cleavage furrow
What phase do chromosomes align on the metaphase plate?
Metaphase
What happens during prometaphase?
The spindle fibers attach to the kinetochores
True or False: The nuclear envelope disintegrates before the start of mitosis.
False
True or false? Mitosis takes place during M phase, which is the longest phase of the cell cycle.
False
Which term describes two recently replicated DNA strands that are joined together just before cell division?
Sister Chromatids
During which stage of mitosis are chromosomes lined up in the center of the cell?
Metaphase
Which stage of mitosis is characterized by the disintegration of mitotic spindles and the formation of two new nuclear membranes?
Telophase
To which part of the centromere do mitotic spindle fibers attach during prometaphase?
Kinetochore
During which substage of mitosis do sister chromatids break apart and start moving to opposite poles of the cell?
Anaphase
Which of the following is a function of the S phase in the cell cycle?
The synthesis of sister chromatids
The copying of chromosomes occurs during which of the following phases of the cell cycle?
S phase
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
True or false? The M phase is characterized by the replication and division of a cell's chromosomes.
False
If an organism normally has 34 chromosomes, how many molecules of DNA should there be in the G1 phase of the cell cycle?
34
Which of the following events would cause the cell cycle to arrest?
Poor nutrient conditions
What is cancer?
abnormal or uncontrolled division of cells
What is a lymphocyte?
a type of white blood cell involved in the immune response
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 plant cell in the process of cytokinesis
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
Disruption of mitotic spindle formation
`The decline of MPF activity at the end of mitosis is due to
The degredation of cyclin
In the cells of some organisms, mitosis occurs without cytoki-nesis. This will result in
cells with more than one nucleus
Which of the following does not occur during mitosis?
Replication of the DNA
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
Which statement provides the best description of the interphase portion of the cell cycle?
During interphase, a cell is metabolically active
What is true of all cancers?
They have escaped normal cell cycle controls