Chapter 12 the Cell Cycle Flashcards
Which of the following events does not occur during prophase of mitosis?
The mitotic spindle breaks down.
Which of the following statements describes a cell that undergoes mitosis but not cytokinesis?
The cell contains more than one nucleus.
DNA replication occurs in __________.
the S phase of interphase in both somatic and reproductive cells
In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle?
Cytokinesis
The complex of DNA and protein that makes up a eukaryotic chromosome is properly called __________.
chromatin
What is the difference between a benign tumor and a malignant tumor?
Cells of benign tumors do not metastasize; those of malignant tumors do.
During interphase, the genetic material of a typical eukaryotic cell is __________.
dispersed in the nucleus as long strands of chromatin
During binary fission in a bacterium __________.
the origins of replication move apart
One event occurring during prophase is __________.
the beginning of the formation of a spindle apparatus
Cytokinesis refers to __________.
division of the cytoplasm
The spread of cancer cells to other locations in the body is known as __________.
metastasis
Checkpoints in the cell cycle control system __________.
regulate the cell cycle through a variety of stop and go signals
Which of the following events occurs during prometaphase of mitosis?
The nuclear envelope fragments.
A cell contains 40 chromatids at the beginning of mitosis. How many chromosomes will it contain at the completion of cytokinesis?
20
Which of the following statements correctly describes the difference(s) between mitosis and binary fission?
Binary fission involves the replication and division of a single chromosome, whereas mitosis involves the division of multiple, replicated chromosomes.
Observations of cancer cells in culture support the hypothesis that cancer cells __________.
do not exhibit density-dependent inhibition
Which of the following events occurs during anaphase of mitosis?
The sister chromatids are pulled apart toward opposite sides of the cell.
Which of the following structures is/are part of the mitotic spindle?
All of the listed responses are part of the mitotic spindle.
The function of the mitotic cell cycle is to produce daughter cells that __________.
are genetically identical to the parent cell (assuming no mutation has occurred)
Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope?
Telophase
Chromatids are __________.
identical copies of each other if they are part of the same chromosome
Which of the following events occurs during telophase of mitosis?
Two distinct daughter nuclei form in the cell.
Which of the following events occurs during metaphase of mitosis?
The chromosomes align along the metaphase plate of the cell.
How many chromatids does a human somatic cell contain after interphase and just prior to mitosis?
92
How does the process of mitosis differ between most eukaryotes and other eukaryotes such as diatoms and dinoflagellates?
The nuclear envelope fragments in most eukaryotes but remains intact in diatoms and dinoflagellates.
The region of a chromosome holding the two double strands of replicated DNA together is called __________.
a centromere
You would know a dividing cell was a plant cell rather than an animal cell if you saw that __________.
it had formed a cell plate
Which event or events occur during anaphase?
All of the listed responses are correct.
Which of the following events does not occur during interphase of the cell cycle?
Separation of the sister chromatids
DNA replication
S
Cell growth stops and the cell divides
M
A cell’s nondividing stage
G0
Cell growth and increase in energy production
G1
Cell growth and preparation for division
G2
Which of the following are reasons the cell cycle must be regulated?
To make sure daughter cells end up with the right number of chromosomes
To make sure cells only divide when conditions are favorable for growth and development of the organism
To allow cells to respond to cues from their internal state and from their environment
T/F Signals that regulate the cell cycle come from outside and inside the cell.
T
T/F Most cells that pass the G1 checkpoint ultimately complete the cell cycle.
T
T/F If a cell does not receive a go-ahead signal at the G1 checkpoint, the cell leaves the cell cycle and dies.
F
T/F Cells move freely through the cell cycle unless they receive a stop signal at a checkpoint when something is wrong.
F
T/F The M checkpoint occurs during prometaphase of mitosis to ensure that all chromosomes are attached to spindles by both kinetochores.
T
The M checkpoint is an example of a checkpoint that is internally controlled by the cell. What would be the potential consequence seen in daughter cells if the cell received a stop signal at this checkpoint but was able to continue to anaphase anyway?
At the completion of mitosis and cytokinesis, the daughter cells could have missing or extra chromosomes.
Which of the following statements are true of cytokinesis in plant cells? Select the two that apply.
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.
What is the best description of the structure of a chromosome in the nucleus of a non-dividing cell?
One long DNA molecule, associated with many proteins.
Which of the following statements best describes microtubules?
Microtubules are made up of subunits of tubulin, and are structures along which substances are transported in the cell.
How can a protein outside the cell cause events to happen inside the cell?
A protein outside the cell can bind to a receptor protein on the cell surface, causing it to change shape and sending a signal inside the cell.
What effect does phosphorylating a protein have on that protein?
Phosphorylation changes the shape of the protein, most often activating it.
Why do some species employ both mitosis and meiosis, whereas other species use only mitosis?
they need both if they are reproducing sexually
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?
92
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?
92
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
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
Why is it difficult to observe individual chromosomes with a light microscope during interphase?
interphase chromosomes are long, thin strands unlike the condensed chromosomes visible in mitosis
Which of the following statements describing kinetochores is correct?
They are sites at which microtubules attach to chromosomes.
Which of the following correctly matches a phase of the cell cycle with its description?
G1, follows cell division
In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?
large cells containing many nuclei
Which of the following occurs in binary fission but not in mitosis with cytokinesis?
duplicated chromosomes attach to the plasma membrane
Cytochalasin B is a chemical that disrupts microfilament formation. With which aspect of cell division would cytochalasin B interfere?
cleavage
_____ is a carcinogen that promotes colon cancer.
fat
Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?
G1
Which of the following is true of benign tumors, but not malignant tumors?
they remain confined to their original site
T/F The second division of meiosis reduces the number of chromosomes in each cell by half.
F
T/F The first division of meiosis reduces the number of chromosomes in each cell by half.
T
T/F Crossing over and synapsis occur after the homologous chromosomes separate in meiosis I.
F
T/F In meiosis II, the daughter cells from meiosis I undergo a very similar division to mitosis.
T
T/F Meiosis occurs in both somatic (body) cells and sex cells.
F
Mitosis can occur in both haploid and diploid cells, but meiosis cannot occur in haploid cells. Why not?
Meiosis produces daughter cells with half the number of chromosome sets of the parent cell; therefore, the parent cell cannot be haploid.
T/F Crossing over occurs at the ends of chromosomes, rather than near the centromeres.
T
T/F Crossing over prevents homologous chromosomes from separating during meiosis I.
F
T/F For crossing over to occur, homologous chromosomes must align precisely early in prophase I so that nonsister chromatids can exchange corresponding segments of DNA.
T
T/F As a result of crossing over, sister chromatids are no longer identical to each other.
T
Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?
DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.
If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.
There would be less genetic variation among gametes.
Eukaryotic chromatin is composed of which of the following macromolecules?
DNA and proteins
After DNA replication, each duplicated chromosome consists of two of which of the following structures?
sister chromatids
What is the name of the region on duplicated chromosomes where the sister chromatids are most closely attached to each other?
the centromere
Beginning with a fertilized egg (zygote), how many cells will be present in the embryo following five rounds of cell division?
32
In a diploid cell with four chromosome pairs (2n = 8), how many centromeres will be found in a nucleus at G2 of the cell division cycle?
8
Students in a biology lab isolated cells in various phases of the cell cycle. A population of cells that have twice the DNA of G1 phase cells was most likely isolated from which of the following part of the cell cycle?
in the G2 phase
Which of the following cellular events occur in the G1 phase of the cell division cycle?
normal growth and cell function
The mitotic spindle plays a critical role in which of the following processes?
separation of sister chromatids
Which of the following statements describes a characteristic feature of metaphase?
alignment of chromosomes on the equator of the cell
Which of the following statements best describes how cytokinesis differs between plant and animal cells?
Plant cells deposit vesicles containing cell wall building blocks on the metaphase plate; animal cells form a cleavage furrow.
FtsZ is a bacterial protein that forms a contractile ring involved in binary fission. Its function is analogous to which of the following structures in eukaryotic cells?
the cleavage furrow of eukaryotic animal cells
At which phase of the cell cycle do centrioles begin to move apart in animal cells?
prophase
In a diploid cell with four chromosome pairs (2n = 8), how many sister chromatids will be found in a nucleus at prophase of mitosis?
16
If there are 24 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?
48
Movement of the chromosomes during anaphase would be most directly affected by a drug that prevents which of the following events?
shortening of microtubules
Which of the following statements best describes a cleavage furrow?
a groove in the plasma membrane between daughter nuclei
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
Which of the following events occurs during interphase of the cell cycle?
replication of the DNA
The drug cytochalasin B blocks the polymerization of actin microfilaments. Which of the following events of the cell cycle in animal cells would be most directly disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol prevents microtubule depolymerization, which interferes with which of the following processes?
the mitotic spindle
Which of the following statements best explains how neurons and some other specialized cells divide infrequently?
They have entered into G0.
Which of the following pairs of molecules make up an active MPF?
cyclin and a cyclin-dependent kinase
Which of the following statements best describes what would happen if MPF (maturation-promoting factor) is introduced into immature frog oocytes that are arrested in G2?
The cells would enter mitosis.
Which of the following statements best describes what happens to MPF during mitosis?
The cyclin component of MPF is degraded.
If all chromosomes are not attached to the mitotic spindle at the M phase checkpoint, the cells would most likely be arrested at which of the following points in the cell division cycle or mitosis?
metaphase
Which of the following molecules is synthesized at specific times during the cell cycle and forms an active complex with a kinase?
cyclin
Which of the following molecules is maintained at a relatively constant level throughout the cell cycle but requires a cyclin to become catalytically active?
Cdk
Which of the following statements best describes density-dependent inhibition?
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells, and they signal each other to stop dividing.
Besides the ability of some cancer cells to over proliferate, which of the following situations is most likely to result in a tumor?
lack of appropriate cell death
Which of the following statements best describes cells in culture that do not exhibit either density-dependent inhibition or anchorage dependence?
The cells show characteristics of tumors.
Which of the following characteristics would be most important for a chemotherapeutic drug designed to treat cancer cells?
It specifically inhibits the cell division cycle in rapidly dividing cells.
Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. Which of the following best explains the association between malignant tumors and chromosomal abnormalities?
Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
