In their experimental work, cell biologists treat living cells with a variety of
ID: 69157 • Letter: I
Question
In their experimental work, cell biologists treat living cells with a variety of drugs, toxins, antibody reagents, and so on. Often the purpose of these kind of experiments is to apply to the cell an agent that inhibits the activity of one particular protein as specifically as possible. Then you can use the resulting phenotype as a clue to what the protein normally does in the cell. For each of the phenotypes below, choose the experimental treatment(s) that would be likely to produce it.
(1) Treat cells with a drug, latrunculin B, that depolymerizes actin filaments into actin monomers and keeps them from re-polymerizing.
(2) Inject into cells a small peptide that prevents the association of myosin II molecules into bipolar filaments.
(3) Treat cells with a drug that inhibits the interaction of kinetochores with microtubules.
(4) Inject into cultured cells an antibody that blocks the function of myosin II
(5) Inject into cells a small peptide that irreversibly caps the plus end of microtubules, preventing them from growing more than 1 or 2 m long
A) The cells will undergo mitosis but not cytokinesis, the result will be large, multinucleate cells.
Answer choices: (1, 2, 3, 4, 5, 5/3, 4/1, 3/2, 4/1/5, 5/3/2, OR 4/1/2)
B) The cells will fail to form a mature mitotic spindle and will be stuck in the cell cycle, probably somewhere in prophase or early prometaphase.
Answer choices: (1, 2, 3, 4, 5, 5/3, 4/1, 3/2, 4/1/5, 5/3/2, OR 4/1/2)
Explanation / Answer
Correct options:
(1) Treat cells with a drug, latrunculin B, that depolymerizes actin filaments into actin monomers and keeps them from re-polymerizing.
(2) Inject into cells a small peptide that prevents the association of myosin II molecules into bipolar filaments.
(4) Inject into cultured cells an antibody that blocks the function of myosin II
Correct options:
(3) Treat cells with a drug that inhibits the interaction of kinetochores with microtubules.
(5) Inject into cells a small peptide that irreversibly caps the plus end of microtubules, preventing them from growing more than 1 or 2 m long
Correct options:
(1) Treat cells with a drug, latrunculin B, that depolymerizes actin filaments into actin monomers and keeps them from re-polymerizing.
(2) Inject into cells a small peptide that prevents the association of myosin II molecules into bipolar filaments.
(4) Inject into cultured cells an antibody that blocks the function of myosin II