Question

If a cell in metaphase of mitosis is fused with a cell in the G${}_1$ phase of the cell cycle, the second nucleus will also begin mitosis. What is the most likely explanation for this behavior?

• A. Since mitosis takes up most of the time in the cell cycle, it will dominate the newly created fused cell
• B. Molecules such as cyclins are in high concentration in the cytoplasm of a dividing cell and will signal the fused cells nucleus to undergo mitosis
• C. Spindle fibers from the first mitotic cell cannot distinguish between the chromosomes of the two nuclei
• D. The cell senses that it has too high of a surface area to volume ratio following fusion and begins division

Answer 1

The correct option is B Molecules such as cyclins are in high concentration in the cytoplasm of a dividing cell and will signal the fused cells nucleus to undergo mitosis

If a cell is in Metaphase of mitosis and is fused with a cell in the G${}_1$ the second nucleus also begins mitosis. This is because a dividing cell releases cyclins, CDKs that are different in each phase of the cell division cycle. Thus, if the cell in G${}_1$ phase is exposed to CDKs of the following phases of the division process the cell will enter into the next phase, that is mitosis.

So, the correct answer is 'Molecules such as cyclins are in high concentration in the cytoplasm of a dividing cell and will signal the fused cells nucleus to undergo mitosis'