Week 9 MasteringBio
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.
What is the name of the microtubule-organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle?
centrosome
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
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? See Concept 12.1 (Page)
92 Mitosis follows the duplication of the cell's DNA
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
The continuity of life is based on heritable information in the form of DNA. How does the process of mitosis faithfully parcel out exact copies of this heritable information in the production of genetically identical daughter cells?
During mitosis, each chromatid of a duplicated chromosome becomes attached to the microtubule of one of the mitotic spindles. At anaphase, mitotic spindles pull the chromatids toward the poles of the cell, therefore forming two identical chromosomal sets at each pole.
One type of eukaryotic cell (line 1) spends 24 minutes in S phase and another type of cell (line 2) spends 48 minutes in S phase. Which of the following statements is the best explanation for the difference in time spent in S phase by cell lines 1 and 2?Amount of DNA per nucleus over the cell division cycle.
Line 2 has more DNA than Line 1
If there are 24 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?
12
Which of the following properties is associated with a cyclin-dependent kinase (Cdk)?
A Cdk is an enzyme that attaches phosphate groups to other proteins.
What is the connection between the mitotic index and how often a cell divides?
Cells dividing more often will have a higher mitotic index than those dividing less often. A higher rate of cell division is correlated with a higher mitotic index, meanwhile a lower rate of cell division is correlated with a lower mitotic index.
Certain unicellular eukaryotes, including diatoms and some yeasts, have mechanisms of nuclear division that resemble intermediate steps in the evolution of mitosis. Which of the following is a characteristic feature of nuclear division in these organisms?
Chromosomes are segregated by a mitotic spindle, but the nuclear envelope remains intact during division.
What is the role of microtubules in mitosis?
Microtubules bind to individual chromosomes. Microtubules shorten, dividing the chromosomes. Microtubules form the mitotic spindle.
Which of the following correctly matches a phase of the cell cycle with its description?
G1, follows cell division
How is the cell division of cancer cells like these misregulated?
Such cells are not inhibited by density. Such cells can divide in the absence of growth factors. Such cells do not require anchorage to a surface in order to divide. Such cells do not respond to signals that normally trigger apoptosis.
How does Taxol stop cell division?
Taxol binds the ends of microtubules, preventing shortening By binding to the ends of microtubules, Taxol prevents chromosomes from separating in anaphase, and thus prevents two nuclei from forming in telophase.
What are the genetic or other changes that might have caused these cells to escape normal cell cycle regulation?
The underlying basis for this altered behavior is a series of genetic and cellular changes, including mutations in genes whose protein products normally regulate the cell cycle. These gene products are often proteins that function in cell signaling pathways.
Which of the following statements describing kinetochores is correct?
They are sites at which microtubules attach to chromosomes. As the spindle depolymerizes, the kinetochores appear to move along the spindle fiber, dragging the attached chromosomes with them.
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.
In which phase of mitosis do the sister chromatids become daughter chromosomes?
anaphase
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in
cells with more than one nucleus.
What is the name of the region on duplicated chromosomes where the sister chromatids are most closely attached to each other?
centromere
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
Which of the following molecules is synthesized at specific times during the cell cycle and forms an active complex with a kinase?
cyclin
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?
disrupting the cleavage furrow formation and cytokinesis.
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
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
Given what you know about chromosome movement and spindle changes during anaphase, predict which type of motor proteins would be present on kinetochore microtubules.
minus end-directed motor proteins
Given what you know about chromosome movement and spindle changes during anaphase, predict which type of motor proteins would be present on nonkinetochore microtubules.
plus end-directed motor proteins
At which phase of the cell cycle do centrioles begin to move apart in animal cells?
prophase
The mitotic spindle plays a critical role in which of the following processes?
separation of sister chromatids
After DNA replication, each duplicated chromosome consists of two of which of the following structures?
sister chromatids
The decline of MPF activity at the end of mitosis is due to
the degradation of cyclin.
