What part of the cell is responsible for controlling cellular activities?

The nucleus is often referred to as the control center of the cell because it houses the cell's genetic material, DNA. The DNA contains the instructions necessary for regulating the activities and functions of the cell, including growth, metabolism, and reproduction. The nucleus orchestrates these processes by controlling gene expression, which determines which proteins are produced, when they are produced, and in what quantities. This regulation is essential for maintaining homeostasis and responding to environmental changes.

In contrast, the cell membrane functions as a barrier and regulates what enters and leaves the cell, but it does not control cellular activities. The cytoplasm is the fluid substance within the cell where many metabolic processes occur, but it lacks the directive role of the nucleus. Ribosomes are responsible for protein synthesis, which is one of the activities directed by the genetic information in the nucleus, but they do not control overall cellular functions.