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67 terms

intro to cell chapter 11

STUDY
PLAY
All human body (somatic) cells divide by mitosis. Skin cells or cells lining the intestinal track would divide about once every _______ , whereas liver cells would divide about onece every ___________.
day ...... year
Mitosis is responsible for what key processes in multicellular eukaryotes?
-all of the listed responses are correct
-sound repair
-reproduction
-growth
all of the listed responses are correct
During what phase of the cell cycle does the DNA become replicated?
S
Mitosis is responsible for what key process in multicellular eukaryotes?
growth, wound repair, and reproduction
What is the difference between a chromatid and a chromosome?
A chromatid is one half of a replicated chromosome, whereas a chromosome consists of DNA wrapped around proteins in a highly organized manner.
n which mitotic phase are the sister chromatids separated and pulled to opposite poles?
anaphase
In which mitotic phase do the chromosomes condense and the mitotic spindle begin to form?
prophase
The division of the cytoplasm following mitosis is called _____.
cytokinesis
MPF, or mitosis-promoting factor, consists of two important cell cycle regulatory proteins called _____.
cyclin and cyclin-dependent kinase (CDK)
Two important checkpoints that regulate the cell's progression through the cell cycle are _____.
G1 and G2
What two types of defects does a cancerous cell possess?
-Cancerous cells are prevented from dividing and have inhibited growth patterns.
-Cancerous cells possess defects that make proteins required for cell growth active and tumor suppressor genes inactive.
-Cancerous cells lack the ability to carry out cellular respiration and photosynthesis.
-Cancerous cells possess defects that make proteins required for cell growth inactive and tumor suppressor genes active.
Cancerous cells possess defects that make proteins required for cell growth active and tumor suppressor genes inactive.
he defining characteristic of a malignant tumor is that _____.
its cells can spread to other parts of the body
The centromere is a region in which
-chromatids remain attached to one another until anaphase.
-metaphase chromosomes become aligned at the metaphase plate
-chromosomes are grouped during telophase
-the nucleus is located prior to mitosis
-new spindle microtubules form at either end
chromatids remain attached to one another until anaphase.
If there are 20 chromatids in a cell, how many centromeres are there?
10
At which phase are centrioles beginning to move apart in animal cells?
prophase
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?
10
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?
centrosome
Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?
-cyclin-dependent kinases
-actin and myosin
-kinetochores
-Golgi-derived vesicles
-centrioles and centromeres
Golgi-derived vesicles
Which of the following are primarily responsible for cytokinesis in animal cells?
-Golgi-derived vesicles
-kinetochores
-centrioles and centromeres
-actin and myosin
-cyclin-dependent kinases
actin and myosin
A group of cells is assayed for DNA content immediately following the S phase and is found to have an average of 16 picograms of DNA per nucleus. How many picograms would be found in each of the daughter cells at the end of Mitosis and cytokinesis?
8
Which of the following is (are) required for motor proteins to function in the movement of chromosomes toward the poles of the mitotic spindle?
-ATP as an energy source
-synthesis of cohesin
-intact centromeres
-a kinetochore attached to the metaphase plate
-an MTOC (microtubule organizing center)
ATP as an energy source
Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis?
-Motor proteins of the kinetochores move the chromosomes along the spindle microtubules
-Nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles
-The chromosomes are "reeled in" by the contraction of spindle microtubules, motor proteins of the kinetochores move the chromosomes along the spindle microtubules, and nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles
-The chromosomes are "reeled in" by the contraction of spindle microtubules
-The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules
The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules
Look at diagrams on section 4 of mitosis and cytokinesis
....
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
Look at diagrams on section 5 of mitosis and cytokinesis
....
Mitosis unfolds through a sequence of stages marked by specific events in the cell. The structural changes in the cell are brought about by a series of tightly coordinated underlying mechanisms. Sort each process into the appropriate bin to indicate the stage of mitosis in which it occurs: prophase, prometaphase, metaphase, anaphase, or telophase.
-kinetochores are motionless in relation to poles of cell
- tubulins assemble into spindle microtubules
-cohesions break down
-spindle microtubules disassemble
-kinetochores move toward poles of cell
-cohesions join sister chromatids of duplicated chromosome
-microtubules attach to kinetochores
prophase: cohesions join sister chromatids of duplicated chromosome, tubulins assemble into spindle microtubules
prometaphase: microtubules attach to kinetochores
metaphase: kinetochores are motionless in relation to poles of cell
anaphase: cohesions break down, kinetochores move toward poles of cell
telophase: spindle microtubules disassemble
During prophase, the microtubules of the mitotic spindle _______.
disassemle, shorten, or lengthen
lengthen
During anaphase, the nonkinetochore microtubules_______ and move past each other, and the kinetochore microtubules _______.
disassemble, shorten, or lengthen
lengthen....shorten
During telophase, the nonkinetochore microtubules _______.
disassemble, shorten, or lengthen
disassemble
In all cells, separation of replicated chromosomes is a prerequisite for cell division. However, the mechanism of chromosome separation in bacteria is distinct from that in eukaryotes in several ways.
Sort the following statements into the appropriate bin: bacteria only, eukaryotes only, or both bacteria and eukaryotes.
-chromosomes replicate before cell division
- chromosome separation begins at the origin of replication on DNA
-before separation, duplicated chromosomes condense
-two copies of the duplicated chromosome are attached at their centromeres before separating
-replicated chromosomes separate by attaching to some other structural feature of the cell
-nuclear envelope fragments, permitting chromosome separation
bacteria only: chromosome separation begins at the origin of replication on DNA
eukaryotes only: before separation duplicated chromosomes condense, nuclear envelope fragments permitting chromosome separation, two copies of the duplicated chromosome are attached at their centromeres before separating
both bacteria and eukaryotes: chromosomes replicate before cell division, replicated chromosomes separate by attaching to some other structural feature of the cell
Cytokinesis in animal cells is accomplished by constriction of the cell along the plane of cell division (formation of a cleavage furrow). In plant cells, which have cell walls, a completely different mechanism of cytokinesis has evolved.
Which of the following statements are true of cytokinesis in plant cells? Select the two that apply.
-The plasma membrane of the parent cell grows inward, eventually joining with the cell plate.
-After chromosome separation is complete, a network of microfilaments forms near the plane of cell division that will separate the two new cells.
-Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
-The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells.
-Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
-The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells.
Look at diagrams on section 6 of mitosis and cytokinesis
....
Nucleoli are present during _____.
interphase
Cytokinesis often, but not always, accompanies _____.
telophase
Chromosomes become visible during _____.
prophase
Centromeres divide and sister chromatids become full-fledged chromosomes during _____.
anaphase
Spindle fibers attach to kinetochores during _____.
prometaphase
look at diagrams on section 7 of mitosis and cytokinesis
....
During prophase a homologous pair of chromosomes consists of _____.
two chromosomes and four chromatids
Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?
-PDGF
-Cdk
-protein kinase
-cyclin
-MPF
Cdk
Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?
-protein kinase
-PDGF
-cyclin
-Cdk
-MPF
MPF
The cyclin component of MPF is destroyed toward the end of which phase?
M
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called _______
cyclins
The MPF protein complex turns itself off by
-activating the anaphase-promoting complex
-activating a process that destroys cyclin components
-activating an enzyme that stimulates cyclin
-exiting the cell
-binding to chromatin
activating a process that destroys cyclin components
Which of the following describe(s) cyclin-dependent kinase (Cdk)?
-Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins
-Cdk is inactive, or "turned off," in the presence of cyclin
-Cdk is present throughout the cell cycle.
-Cdk is inactive, or "turned off," in the presence of cyclin and it is present throughout the cell cycle
-Cdk is an enzyme that attaches phosphate groups to other proteins.
Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins
After which checkpoint is the cell first committed to continue the cell cycle through M?
G1
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 ______.
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 with a 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
Look at diagrams on section 2 of control of the cell cycle
....
Which of the following is a function of the S phase in the cell cycle?
-The synchronization of organelle division
-The synthesis of sister chromatids
-The separation of sister chromatids
-The sorting of chromosomes
The synthesis of sister chromatids
The copying of chromosomes occurs during which of the following phases of the cell cycle?
-S phase
-G1 phase
-M phase
-G2 phase
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 do not divide by mitosis.
-The number of chromosomes decreases with each generation
-The cells get smaller with each generation.
-Frog embryos do not have DNA
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?
-Chromosomes lined up along the metaphase plate
-Synthesis of cyclins by growth factors and activation of a cyclin-Cdk complex
-Poor nutrient conditions
-Complete chromosome replication
Poor nutrient conditions
When cells were first taken from Henrietta Lacks, she was _____.
suffering from cervical cancer
How did doctors harvest and culture cells from Henrietta Lacks?
Cells were taken while she was being treated for cancer many years ago, and these cells have been cultured in the lab ever since
Did doctors ask Henrietta Lacks' permission to take her cells, and was she paid for them?
She was never told that her cells were being taken, and neither she nor her family has been compensated.
What property of Henrietta Lacks' cells was most unusual when they were grown in the laboratory?
They continue to divide and multiply after decades of culture
Cells taken from Henrietta Lacks have been used for experiments leading to _____.
the development of a polio vaccine, new treatments for cancer, and tests of the effects of atomic radiation on life