Campbell Biology: Concepts & Connections (8th Edition)
8th Edition
ISBN: 9780321885326
Author: Jane B. Reece, Martha R. Taylor, Eric J. Simon, Jean L. Dickey, Kelly A. Hogan
Publisher: PEARSON
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Chapter 4, Problem 19TYK
SCIENTIFIC THINKING Microtubules often produce movement through their interaction with motor proteins. But in some cases, microtubules move cell components when the length of the microtubule changes. Through a series of experiments, researchers determined that microtubules grow and shorten as tubulin proteins are added or removed from their ends. Other experiments showed that microtubules make up the spindle apparatus that “pulls” chromosomes toward opposite ends (poles) of a dividing cell. The figures below describe a clever experiment done in 1987 to determine whether a spindle microtubule shortens (depolymerizes) at the end holding a chromosome or at the pole end of a dividing cell.
Experimenters labeled the microtubules of a dividing cell from a pig kidney with a yellow fluorescent dye. As shown on the left half of the diagram below, they then marked a region halfway along the microtubules by using a laser to eliminate the fluorescence from that region. They did not mark the other side of the spindle (right side of the figure).
The figure below illustrates the results they observed as the chromosomes moved toward the opposite poles of the cell.
The figure below illustrates the results they observed as the chromosomes moved toward the opposite poles of the cell.
Describe these results. What would you conclude about where the microtubules depolymerize from comparing the length of the microtubules on either side of the mark? How could the experimenters determine whether this is the mechanism of chromosome movement in all cells?
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Part of cell division is that chromosomes are moved the center of the cell and then back to the poles of each newly made daughter cell. These chromosomes are moved to the center of the cell by..
Select one:
a. Myosin walking on microtubules towards the center of the cell (slow growing end of microtubule)
b. Oar-like motion of myosin with microfilaments causing each half of the cell to move closer together
c. kinesins walking on microtubules towards the center of the cell (fast growing end of microtubule)
d. vesicles floating on microfilaments of the cortical cytoskeleton
You view a mature, living plant cell such as an epidermal cell under the light microscope. You view the cell at sufficiently-high magnification and you have also stained the cell for chromatin. The cell has a nucleus, yet you cannot see chromosomes, at least in their typical ’sausage-formed’ shape as we all know them from textbooks. Why is that?
Scientists often extract DNA from the nucleus of cells for analysis or use. This process breaks the cell membrane, spins the solution to remove the large particles through high g-force, adds alcohol to make the DNA less soluble aqueous solution, then spins the solution again to pull the DNA out of solution. Consider a cell in metaphase compared to a cell in rest (not in the cell cycle leading to cell division). What properties of a metaphase cell might let you extract more DNA compared to the resting cell? Are there any that might make the extraction more difficult?
Chapter 4 Solutions
Campbell Biology: Concepts & Connections (8th Edition)
Ch. 4 - Label the structures in this diagram of an animal...Ch. 4 - Prob. 2TYKCh. 4 - Prob. 3TYKCh. 4 - Which of the following clues would tell you...Ch. 4 - Prob. 5TYKCh. 4 - What four cellular components are shared by...Ch. 4 - Describe two different ways in which cilia can...Ch. 4 - In which cell would you find the most lysosomes?...Ch. 4 - Prob. 9TYKCh. 4 - Prob. 10TYK
Ch. 4 - In which cell would you find the most...Ch. 4 - In what ways do the internal membranes of a...Ch. 4 - Is this statement true or false? Animal cells have...Ch. 4 - Describe the structure of the plasma membrane of...Ch. 4 - Prob. 15TYKCh. 4 - Describe the pathway of the protein hormone...Ch. 4 - How might the phrase ingested but not digested be...Ch. 4 - Cilia are found on cells in almost every organ of...Ch. 4 - SCIENTIFIC THINKING Microtubules often produce...
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- The drug taxol is extracted from the bark of yew trees. It binds tightly to microtubules and stabilizes them. When added to cells, it causes much of the free tubulin to assemble into microtubules. Taxol can be used as an anticancer drug. At the molecular level, what does the drug prevent? At the cellular level, what part of cell division does it prevent? Be specific.arrow_forwardWhich of the cytoskeletal elements shown in the diagram helps to move chromosomes to opposite poles during mitosis?arrow_forwardScientists in a lab have isolated a substance that prevents cells from synthesizing spindle fibres. How would this substance affect cell division? Explain.arrow_forward
- Consider the proper progression of the cell cycle. In one of the first steps, the __ Select one: a. cell membrane breaks down as the micrtubulin filaments dissolve b. cell membrane breaks down as the intermediate filaments dissolve c. nuclear membrane breaks down as the actin filaments dissolve d. cell membrane breaks down as the actin filaments dissolve e. nuclear membrane breaks down as the intermediate filaments dissolvearrow_forwardAn antibody that binds to myosin prevents the movement of myosin molecules along actin filaments. What is the main role of an antibody? What would be the effect of injecting this antibody into cells on the movement of chromosomes at anaphase? Explain your answer. What would be the effect of injecting this antibody into cells on cytokinesis? Explain the result.arrow_forwardSCIENTIFIC INQUIRY Although both ends of a microtubulecan gain or lose subunits, one end (called the plus end)polymerizes and depolymerizes at a higher rate than theother end (the minus end). For spindle microtubules, the plusends are in the center of the spindle, and the minus ends areat the poles. Motor proteins that move along microtubulesspecialize in walking either toward the plus end or towardthe minus end; the two types are called plus end–directedand minus end–directed motor proteins, respectively. Givenwhat you know about chromosome movement and spindlechanges during anaphase, predict which type of motorproteins would be present on (a) kinetochore microtubulesand (b) nonkinetochore microtubules.arrow_forward
- In cancer, cells divide out of control. Thus, chemicals that interfere with cell division might be used to stop cancer cells. How many of the following might stop human cancer cells? I. A chemical that prevents the phosphorylation of lamins. II. A chemical that prevents microtubule shortening. III. A chemical that prevents actin-myosin contraction. IV. A chemical that prevents the dephosphorylation of lamins. O 2 O 4 O 1arrow_forwardCancer is a disease in which cells exhibit uncontrolled cell division. Drugs used in the study of microtubules are also used in the treatment of cancer. Why are drugs that disrupt microtubules more useful in the treatment of cancer than are drugs used to disrupt microfilaments? What is the name of the category of these drugs that describes their function?arrow_forwardWhat would you expect to see in a cell that contains a large pool of free GTP-tubulin dimers? microtubules would grow longer microtubules would shrink microtubules would contain GTP caps O A & C O B& Carrow_forward
- Biologists have long been interested in the effects of radiation on cells. In one experiment, researchers examined the effect of radium on mitosis of chick embryo cells growing in culture. A population of experimental cells was examined under the microscope for the number of cells in telophase (as a measure of mitosis occurring) before, during, and after exposure to radium. The results are shown in the Figure. What is the effect of radium exposure on mitosis? Source: R. G. Canti and M. Donaldson. 1926. The effect of radium on mitosis in vitro. Proceedings of the Royal Society of London, Series B, Containing Papers of a Biological Character 100:413419.arrow_forwardThe eukaryotic cell in the photo on the left is in the process of cytoplasmic division. Is this cell from a plant or an animal? How do you know?arrow_forwardSpindle fibers that are necessary to separate sister chromatids during mitosis are synthesized by...? lysosomes centrosomes ribosomes chromosomesarrow_forward
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