It allows movement of substances within a cell

It allows movement of substances within a cell.
It regulates what enters and exits the cell; it also protects the cell from its surroundings by allowing only selected substances into the cell and keeping unwanted substances out.
Its major function is to produce cellular respiration, it also regulates cellular metabolism.
They digest unwanted organelles and food particles e.g. if they are worn out or there are too many of them, it also digests engulfed bacteria or viruses.
It transports molecules to various locations within a cell.
It transports, modifies and packages lipids and proteins into vesicles and then sends them to a specific destination within the cell.
It synthesises and processes lipids.
It modifies proteins, e.g. folding them into their correct shapes, produced by ribosomes.
They build proteins out of amino acids.
It stores DNA and controls the cell’s activities; these include intermediary metabolism, protein synthesis, cell division, and growth.