The cell membrane, also known as the plasma membrane, has the important function of protecting the cell and regulating what enters and exits it. It allows certain substances, like nutrients and waste, to pass through while keeping others out. The mitochondria, on the other hand, are responsible for producing energy for the cell. This energy, in the form of ATP molecules, is essential for carrying out various cellular activities and functions. The mitochondria are often referred to as the "powerhouse" of the cell due to their role in energy production.
