Question

which structure is the arrow pointing to? what is the function of this organelle?

Explanation:

In a cell, the nucleus is a prominent organelle usually stained darker in microscopy images. It contains the cell's genetic material and acts as the control - center for the cell.

Answer:

The structure the arrow is pointing to is likely the nucleus. The function of the nucleus is to store genetic information (DNA) and control cellular activities such as growth, metabolism, and reproduction.