Question

Describe the events that characterize each stage of mitosis.

Short answer

Answer: In mitosis, the stages and their characterized events are as follows: 1. Prophase: Chromosomes condense and become visible, the nuclear envelope breaks down, centrosomes move to opposite sides of the cell, and spindle fibers form. 2. Prometaphase: The nuclear envelope completely breaks down, centrosomes continue to move to opposite sides, and spindle fibers attach to the centromere of each chromosome. 3. Metaphase: Chromosomes align at the metaphase plate, and spindle fibers ensure sister chromatids are attached to spindle fibers from opposite centrosomes. 4. Anaphase: Sister chromatids separate, and individual chromosomes move to opposite poles of the cell. 5. Telophase: Chromosomes decondense, nuclear envelopes reassemble, and spindle fibers disassemble. After telophase, cytokinesis occurs, resulting in two identical daughter cells with the same genetic material as the parent cell.

Step-by-step solution

Introduction to Mitosis

Mitosis is the process of cell division, in which the chromosomes of a parent cell are duplicated and distributed into two identical daughter cells. This process ensures that each cell has the correct number of chromosomes. Mitosis consists of several stages, which will be discussed below.

Stage 1: Prophase

Prophase is the first stage of mitosis. During this stage, the following events occur: 1. The chromosomes condense and become visible under a microscope. 2. The nuclear envelope, which surrounds the nucleus, starts to break down. 3. The centrosomes (structures that organize the spindle fibers) move to the opposite sides of the cell. 4. Spindle fibers (protein structures responsible for pulling the chromosomes apart) begin to form.

Stage 2: Prometaphase

Prometaphase is the second stage of mitosis. During this stage, the following events occur: 1. The nuclear envelope completely breaks down, allowing the spindle fibers to access the chromosomes. 2. The centrosomes continue to move to the opposite sides of the cell. 3. Spindle fibers attach to the centromere of each chromosome. The centromere is the region where the sister chromatids (two identical copies of a single chromosome) are joined together.

Stage 3: Metaphase

Metaphase is the third stage of mitosis. During this stage, the following events occur: 1. The chromosomes align at the center of the cell, also known as the metaphase plate. 2. The spindle fibers ensure that each sister chromatid is attached to spindle fibers from opposite centrosomes. This ensures that each daughter cell will receive one sister chromatid from each chromosome pair.

Stage 4: Anaphase

Anaphase is the fourth stage of mitosis. During this stage, the following events occur: 1. The sister chromatids are separated as the spindle fibers pull them toward opposite sides of the cell. 2. The separated sister chromatids, now considered as individual chromosomes, move to the opposite poles of the cell.

Stage 5: Telophase

Telophase is the fifth and final stage of mitosis. During this stage, the following events occur: 1. The chromosomes reach the cell poles and begin to decondense (spread out and return to their usual form). 2. The nuclear envelopes reassemble around the separated chromosomes, forming two nuclei within the cell. 3. The spindle fibers disassemble. After telophase, cytokinesis (the division of the cytoplasm) occurs, resulting in two identical daughter cells, each with the same genetic material as the parent cell.