Passage VI

Microtubules (MTs), which are structural components of cells, continuously elongate and shorten. An MT in catastrophe stops elongating and starts to shorten. An MT in rescue stops shortening and starts to elongate. When a cell enters mitosis from interphase, these transitions contribute to the rearrangement of the MT structure to form the mitotic spindle.

Table 1 shows the values of 3 parameters that were set in 6 computer-simulation models (CSMs A—F) of MT populations. It also shows the known values of the parameters for interphase cells and mitotic cells.

Figure 1 compares, for 3 MT characteristics, the average values predicted by the CSMs with the known average values for the 2 cell types.

Table and figure adapted from N. R. Gliksman et al. , "How the Transition Frequencies of Microtubule Dynamic Instability (Nucleation, Catastrophe, and Rescue) Regulate Microtubule Dynamics inInterphase and Mitosis: Analysis Using a Monte Carlo Computer Simulation." ©1993 by The American Society for Cell Biology.

38. The computer simulations determined that CSM D was a good model for MT populations in mitotic cells. Based on the value of the catastrophe frequency and the value of the rescue frequency for CSM D in Table 1, a scientist concluded that in mitotic cells the catastrophe frequency is likely to be higher than the rescue frequency. Is this conclusion valid ?

Answer and Explanation

Your Answer is

Correct Answer is G

Explanation

According to the question stem, it can be known that CSM D is representative and can represent the parameters of unknown mitotic cells. Therefore, according to the parameters of CSM D in table 1, it can be known that the catastrophe frequency (0.056) is greater than the rescue frequency (0.044)