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?

Verified step by step guidance

1. Examine the figure: The image shows chromosomes attached to microtubules via kinetochores. A mark is placed on the microtubules (red section) to track changes in length as chromosomes move toward opposite poles during cell division.
2. Describe the results: The marked region of the microtubules remains stationary, while the microtubules shorten on the side closer to the poles. This suggests that depolymerization occurs at the pole end of the microtubules.
3. Conclude the mechanism: Based on the observation, microtubules depolymerize at the pole end, pulling chromosomes toward the poles. This supports the idea that microtubule depolymerization drives chromosome movement during anaphase.
4. Propose a method to test universality: To determine if this mechanism is consistent across all cells, experimenters could repeat the marking experiment in different cell types and organisms, observing whether depolymerization consistently occurs at the pole end.
5. Suggest additional experiments: Experimenters could use inhibitors that block microtubule depolymerization at the poles and observe whether chromosome movement is disrupted, further confirming the role of depolymerization in chromosome movement.

Key Concepts

Microtubule Dynamics

Microtubules are dynamic structures composed of tubulin proteins that undergo polymerization and depolymerization. During cell division, they form the mitotic spindle, which is crucial for chromosome movement. The length of microtubules can change rapidly, influencing their ability to exert forces on chromosomes as they move toward opposite poles of the cell.

Chromosome Segregation

Chromosome segregation is the process by which chromosomes are separated into two daughter cells during cell division. This involves the attachment of microtubules to kinetochores on chromosomes, allowing for their movement. Observing the length of microtubules on either side of the chromosomes can provide insights into how effectively they are pulling the chromosomes apart.

Experimental Validation

To determine if the observed mechanism of chromosome movement is universal across all cells, experimenters can conduct comparative studies using different cell types. Techniques such as live-cell imaging and pharmacological manipulation of microtubule dynamics can help assess whether similar mechanisms govern chromosome movement in various organisms, providing a broader understanding of cell division.