chapter 12 mastering
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.
discrete chromosomes are now visible; each consists of two aligned, identical sister chromatids. Later the nuclear envelope will fragment.
Prometaphase
the chromosomes are condensing and the nucleolus is beginning to disappear. The mitotic spindle is starting to form
Prophase
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
The___ are the organizing centers for microtubules involved in separating chromosomes during mitosis
centrosome(s)
During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called____
chromatin
Cytochalasin B is a chemical that disrupts microfilament formation. With which aspect of cell division would cytochalasin B interfere?
cleavage
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.
the chromatids of each chromosome have separated, and the daughter chromosomes are moving to the ends of the cell as their kinetochore microtubules shorten.
Anaphase
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 events characterizes the beginning of anaphase?
enzymatic cleavage of cohesin
Eukaryotic chromatin is composed of which of the following macromolecules?
DNA and proteins
Which statement provides the best description of the interphase portion of the cell cycle?
During interphase, a cell is metabolically active.
If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct?
Each chromosome is made of a complex of DNA and associated proteins.
Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in
G1
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 correctly matches a phase of the cell cycle with its description?
G1, follows cell division
Nucleoli are present during _____.
Interphase
he spindle is complete, and the chromosomes, attached to microtubules at their kinetochores, are all at the plate.
Metaphase
daughter nuclei are forming. Cytokinesis has started: The cell plate, which will divide the cytoplasm in two, is growing toward the perimeter of the parent cell.
Telophase
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 statements describing kinetochores is correct?
They are sites at which microtubules attach to chromosomes.
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 statements describes a characteristic feature of metaphase?
alignment of chromosomes on the equator of the cell
Centromeres divide and sister chromatids become full-fledged chromosomes during _____.
anaphase
After chromosomes condense, the___ is the region where the identical DNA molecules are most tightly attached to each other.
centromere(s)
One difference between cancer cells and normal cells is that cancer cells
continue to divide even when they are tightly packed together.
Which of the following molecules is synthesized at specific times during the cell cycle and forms an active complex with a kinase?
cyclin
In most eukaryotes, division of the nucleus is followed by___when the rest of the cell divides.
cytokinesis
During telophase, the nonkinetochore microtubules___
disassemble
Students in a biology lab isolated cells in various phases of the cell cycle. A population of cells that have 1 1/2 times the DNA of G1 phase cells was most likely isolated from which of the following parts of the cell cycle?
in the S 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
In dividing cells, most of the cell's growth occurs during____
interphase.
During mitosis, microtubules attach to chromosomes at the____
kinetochore(s)
During prophase, the microtubules of the mitotic spindle___
lengthen
During anaphase, the nonkinetochore microtubules___ and move past each other, and the kinetochore microtubules____
lengthen, shorten
The mitotic phase encompasses both
mitosis and cytokinesis
The___ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.
mitotic spindle(s)
Which of the following cellular events occur in the G1 phase of the cell division cycle?
normal growth and cell function
Spindle fibers attach to kinetochores during _____.
prometaphase
Chromosomes become visible during _____.
prophase
Which of the following occurs during S phase?
replication of the DNA
The mitotic spindle plays a critical role in which of the following processes?
separation of sister chromatids
Movement of the chromosomes during anaphase would be most directly affected by a drug that prevents which of the following events?
shortening of microtubules
DNA replication produces two identical DNA molecules, called___ which separate during mitosis.
sister chromatid(s)
After DNA replication, each duplicated chromosome consists of two of which of the following structures?
sister chromatids
Cytokinesis often, but not always, accompanies _____.
telophase
What is the name of the region on duplicated chromosomes where the sister chromatids are most closely attached to each other?
the centromere
During _____ both the contents of the nucleus and the cytoplasm are divided.
the mitotic phase