Use the following information to answer the questions below.
Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.
-The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?
A) spindle formation
B) spindle attachment to kinetochores
C) DNA synthesis
D) cell elongation during anaphase
E) cleavage furrow formation and cytokinesis

Question

Quizplus · Accepted Answer

Cytochalasin B disrupts the function of actin, which is crucial for the formation of the contractile ring during cytokinesis (the final stage of cell division). Thus, the cleavage furrow formation and cytokinesis (E) would be most disrupted by the drug. The other options, spindle formation (A), spindle attachment to kinetochores (B), DNA synthesis (C), and cell elongation during anaphase (D), are not directly dependent on actin and would not be as affected by the drug.

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