When writing a media response essay, ensure that your thesis statement

Your thesis statement should have your viewpoint in it and the thing that you would be trying to prove during the course of your expository essay. Then, later in the body paragraphs, you would write things that support your viewpoint and try to present a problem or persuade someone something.

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.