Question

If a cell has a severely damaged mitochondria, how can that effect the whole cell?

Answer 1

The mitochondria are sometimes called the "power houses" of the cell.
They supply the cell with energy.

The way that they do this is to make ATP (adenosine triphosphate).
ATP is a molecule that stores energy that the cell can use, wherever and whenever it needs it.

Without ATP, the cell wouldn't have energy.
Without energy, none of the chemical reactions would not happen.
And if chemical reactions don't happen, the life cannot be sustained.

In other words, the cell would die.