During anaphase in onion root tip cells, sister chromatids separate and move toward opposite poles of the cell, contributing to cell elongation.
Detailed Explanation of Anaphase in Onion Root Tip Cells:
Anaphase is a critical stage of mitosis, the process of cell division in onion root tip cells (and other eukaryotic cells). Here's a breakdown of what happens:
- Sister Chromatid Separation: The centromeres that hold the sister chromatids together split. Each sister chromatid now becomes an individual chromosome.
- Movement to Opposite Poles: Motor proteins associated with the kinetochores (structures on the chromosomes) pull the chromosomes along the spindle fibers (microtubules) toward opposite poles of the cell. This movement is driven by the shortening of kinetochore microtubules and the elongation of non-kinetochore microtubules.
- Cell Elongation: As the chromosomes move apart, the non-kinetochore microtubules lengthen, causing the cell to elongate. This is crucial for physically separating the sets of chromosomes into two distinct regions of the cell.
Significance in Onion Root Tip Cells:
Observing anaphase in onion root tip cells is a common educational activity because:
- Rapid Cell Division: Root tips are regions of active cell division, making it easier to find cells in various stages of mitosis.
- Clear Chromosome Visibility: The chromosomes are relatively large and easily visible under a microscope with proper staining techniques.
Summary:
In essence, anaphase in onion root tip cells is characterized by the splitting of sister chromatids and their migration to opposite ends of the cell, accompanied by cell elongation, ensuring each daughter cell receives a complete set of chromosomes.
