Bio I Chapter 12 The Cell Cycle
A cell contains 40 chromatids at the beginning of mitosis. How many chromosomes will it contain at the completion of cytokinesis?
20
How many chromatids does a human somatic cell contain after interphase and just prior to mitosis?
92
*Density-dependent inhibition is explained by which of the following processes?*
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells, and they signal each other to stop dividing.
*The unlettered circle at the top of the figure shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A to E show various combinations of these chromosomes What is the correct chromosomal condition at prometaphase of mitosis?.*
B
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.
What is the difference between a benign tumor and a malignant tumor?
Cells of benign tumors do not metastasize; those of malignant tumors do.
In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle?
Cytokinesis
*The beginning of anaphase is indicated by which of the following processes?*
Enzymatic cleavage of cohesin.
Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?
G1
Which event or events occur during anaphase?
Identical chromatids move to opposite poles The centromeres divide The centrioles are at opposite poles A spindle made of microtubules is present
Which of the following structures is/are part of the mitotic spindle?
Kinetochore microtubules Nonkinetochore microtubules The aster Centrosome
*How is plant cell cytokinesis different from animal cell cytokinesis?*
Plant cells deposit vesicles containing cell wall building blocks on the metaphase plate; animal cells form a cleavage furrow.
Which of the following events does not occur during interphase of the cell cycle?
Separation of the sister chromatids
Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope?
Telophase
A cell biologist examined the DNA content of a cell from a fruit fly larva during the G1 phase and determined that it had 150 units of DNA. After measuring the DNA content of the same type of cell after the G2 phase, it was discovered that the cell had 300 units of DNA. How is this possible?
The DNA was replicated during the S phase of interphase, which occurs between the two G phases.
Which of the following statements describes a cell that undergoes mitosis but not cytokinesis?
The cell contains more than one nucleus.
Which of the following events occurs during metaphase of mitosis?
The chromosomes align along the metaphase plate of the cell.
*Once a cell enters mitosis, the molecules that activate division must be turned off. What happens to MPF during mitosis?*
The cyclin component of MPF is degraded.
Which of the following events does not occur during prophase of mitosis?
The mitotic spindle breaks down.
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.
Which of the following events occurs during prometaphase of mitosis?
The nuclear envelope fragments.
Which of the following events occurs during anaphase of mitosis?
The sister chromatids are pulled apart toward opposite sides of the cell.
Why do some species employ both mitosis and meiosis, whereas other species use only mitosis?
They need both if they are producing animal gametes.
Which of the following events occurs during telophase of mitosis?
Two distinct daughter nuclei form in the cell.
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.
The region of a chromosome holding the two double strands of replicated DNA together is called __________.
a centromere
*Metaphase is characterized by ________.*
alignment of chromosomes on the equator of the cell
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)
The complex of DNA and protein that makes up a eukaryotic chromosome is properly called __________.
chromatin
Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division?
cleavage
*One difference between cancer cells and normal cells is that cancer cells*
continue to divide even when they are tightly packed together.
*What two components constitute an active MPF?*
cyclin and a cyclin-dependent kinase
During interphase, the genetic material of a typical eukaryotic cell is __________.
dispersed in the nucleus as long strands of chromatin
Cytokinesis refers to __________.
division of the cytoplasm
Observations of cancer cells in culture support the hypothesis that cancer cells __________.
do not exhibit density-dependent inhibition
____ is a carcinogen that promotes colon cancer.
fat
Chromatids are __________.
identical copies of each other if they are part of the same chromosome
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
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 interphase of the cell cycle?*
replication of the DNA
*The mitotic spindle plays a critical role in which of the following processes?*
separation of sister chromatids
DNA replication occurs in __________.
the S phase of interphase in both somatic and reproductive cells
One event occurring during prophase is __________.
the beginning of the formation of a spindle apparatus
During binary fission in a bacterium __________.
the origins of replication move apart
