1. Biologists around the world spend a great deal of time studying the cytoskele
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Question
1. Biologists around the world spend a great deal of time studying the cytoskeleton of cells. Some of the research tools they use include chemicals that interfere with the structure of the cytoskeletal elements or with the activities of the motor proteins that associate with the cytoskeleton to facilitate movement. For example, a family of compounds called cytochalasins disrupts the normal assembly and disassembly of microfilaments. Another compound called colchicine binds to tubulin and prevents the assembly of microtubules. The function of dynein is prevented by a compound known as EHNA (erythro-9-[3-2-(hydroxynonyl)] adenine), and blebbistatin inhibits the activity of myosin. Use this information to answer the following questions. One or more drugs may be chosen for each answer. 1a. Which of the above drug(s) would block the duplicated chromosomes in a dividing cell from traveling to opposite ends of the cell along the mitotic spindle apparatus? Explain briefly. 1b. Which of the above drug(s) would have the greatest effect on cellular junctions that hold neighboring cells in a tissue together? Explain briefly
Explanation / Answer
The following drugs block the duplicated chromosomes in a dividing cell from traveling to opposite ends of the cell along the mitotic spindle apparatus:
Cytochalasin – it inhibits actin polymerization, blocks the function of actin of cleavage furrow formation. Therefore, cells treated with cytochalasin appear binucleated, since cleavage furrow is not formed
Coclchicine: binds to tubulin, inhibits microtubule formation
EHNA (erythro-9-[3-(2-Hydroxynonyl)]adenine ): prevents axonemal dynein ATPase activity and prevents cells motility (Dyenein: has multiple functions; prevent sliding of microtubules, helps organelle transport in cytoplasm, movement of chromosomes and positioning of spindle for cell division, assist cytokinesis)
Blebbistatin: It is a reversible inhibitor of non-muscle myosin-II, prevents contration of cytokinetic ring, blocks cell blebbing, and disrupts directed cell migration and cytokinesis
Drugs that interfere with cellular junctions are as follows:
Colchicine: Since microtubules are necessary to hold the cell junctions, disruption leads to cell-cell and cell-matrix disruption
EHNA (erythro-9-[3-(2-Hydroxynonyl)]adenine ): The drug affects microtubules, hence effects cellular junctions
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