Question

At which stage of mitosis, the chromatids separate and start moving towards poles? (a) Prophase (b) Metaphase (c) Anaphase (d) Telophase

Short answer

(c) Anaphase

Step-by-step solution

Understanding each stage of mitosis

Firstly, enumerate and understand the typical characteristics of each stage for accurate selection. In prophase, the chromosomes condense and become visible. During metaphase, the chromosomes align in the middle of the cell. In anaphase, the chromosomes separate and move towards opposite ends of the cell. Lastly, in telophase, the separated chromosomes reach the ends of the cell and new nuclei form.

Identifying the correct stage

Go through each stage and locate where the chromatids separate and start moving towards the poles. This happens during anaphase, so the correct answer is (c) Anaphase.

Key concepts

Anaphase

Understanding anaphase is crucial when studying cell division. Anaphase marks a defining moment in the process of mitosis, the stage where replicated chromosomes, which were previously attached, are split and pulled apart. This is facilitated by the spindle fibers, which shorten and pull the sister chromatids towards opposite poles of the cell. The significance of anaphase lies in its role in ensuring that each new cell will receive an identical set of chromosomes.

During anaphase, the proteins that bind the sister chromatids together are cleaved, allowing them to separate. This separation is essential for proper genetic distribution. A failure in this process can lead to genetic disorders due to the unequal distribution of genetic material. By the end of anaphase, the cell prepares to enter the next stage, telophase, moving towards the completion of cell division.

Chromatid Separation

The process of chromatid separation is central to genetic stability and occurs during anaphase of mitosis. Chromatids, which are identical copies of a single chromosome, are joined together by a centromere. Once the cell ensures that all chromosomes are correctly attached to the spindle apparatus, a signal is given for the onset of anaphase. Enzymes then degrade the proteins holding the sister chromatids together, freeing them to move to opposite sides of the cell.

Chromatid separation represents the pivotal step for genetic material division and must be precise. The chromatids, now called daughter chromosomes, are pulled by motor proteins along the spindle fibers to ensure that each future daughter cell will have the same number of chromosomes. In effect, this meticulous process safeguards the transmission of genetic information to the offspring cells.

Mitotic Phases

Mitosis is a complex process, segmented into distinct phases to ensure the accurate replication and distribution of a cell's genetic material. Each phase serves a specific purpose, collaborating to complete cell division efficiently. The primary phases include prophase, during which chromosomes condense and the spindle apparatus forms; metaphase, where chromosomes align along the metaphase plate; anaphase, where the pivotal separation of chromatids occurs; and telophase, the stage directly following anaphase, where the cell prepares to completely divide into two new cells, a process known as cytokinesis.

Each of these mitotic phases requires rigorous regulation. Checkpoints exist to verify the proper completion before advancing to the next phase, thereby maintaining the fidelity of cellular replication. This intricate orchestration ensures that each daughter cell is a viable and accurate copy of the parent cell.