Caption: This is part of an onion plant magnified about 40 times so you can see individual cells. Why do some of the cells have stringy parts instead of round nuclei? Those cells are in different stages of “mitosis,” the process of making a new cell. During mitosis, the membrane of the nucleus breaks down, freeing the DNA to make a copy of itself. Those stringy parts are bunches of DNA called chromosomes. Once the DNA has been duplicated, the cell splits, creating two new cells with identical parts. (Carolina K. Smith, MD/ Shutterstock) Read More