Question

Researchers are studying the last two phases of mitosis, anaphase and telophase, in actively dividing cancer cells. Different fluorescent probes are used to label various cellular components in these cells. Under the microscope, fluorescently labeled DNA appears blue, the nuclear envelope appears green, and the mitotic spindle appears red. Given this, green fluorescence would be most intense during:

Answer 1

Answer: Telophase

Explanation:

Mitosis is a process of division of the nucleus, which consists of the equal sharing of genetic material (DNA). This type of division occurs in somatic cells and the next step after mitosis is the division of the cytoplasm (cytokinesis), to form two genetically identical daughter cells.

First, it is necessary for the genetic material to be duplicated, so that each newly created cell receives the correct number of chromosomes (structure smade up of DNA). To separate these chromosomes, during anaphase, the chromosomes are anchored to the spindle microtubules and aligned at the metaphase plate (the center of the cell). The sister chromatids (two copies of a chromosome) are separated by the microtubules anchored to their kinetochores as they disassemble, heading toward the respective centrosomes (an organelle in which microtubules grow). Then, the microtubules pushing the centrosomes (and the set of chromosomes associated with them) toward opposite ends of the cell. Since it is necessary for the chromosomes to go to the poles of the cell, new cells are formed. So in this step, it is necessary that the nuclear envelope is not present (otherwise, the nucleus could not divide).

During telophase, microtubules not attached to kinetochores continue to elongate, further stretching the cell. The sister chromosomes are each associated with one of the poles, and as the division of the nucleus is completed, the nuclear envelope reforms around both chromosome sets, using fragments of the nuclear envelope of the original cell. The chromosomes are decondensed back into chromatin and only the cytokineses remain.

The fluorophore labels proteins that are part of the nuclear membrane and as telophase forms back, these proteins are expressed more. So, since the proteins of the nuclear envolope are labeled with a green fluoroforum, the green fluorescence would be most intense during telophase. Therefore there will be more intensity of green color compared to anaphase where the nuclear membrane is disintegrated.