"The surface area inside the mitochondria is like the table top where the reactions to break down food can take place. The more tabletop space you have, the more energy you can create. All around inside the mitochondria is a fluid called MATRIX."
The link contains a pretty good explanation for most parts of the mammalian cell.
Feel free to be the first
Please review the linked page for context.
If you can think of something better than this,
please add it to the database