Download Mighty Mitochondria

Mighty Mitochondria
Turning on the Powerhouse
Mitochondria are known as the powerhouses of the cell. They are organelles that act like a digestive system
that takes in nutrients, breaks them down, and creates energy for the cell. The process of creating cell energy
is known as cellular respiration. Most of the chemical reactions involved in cellular respiration happen in the
mitochondria. A mitochondrion is shaped perfectly to maximize its efforts.
Mitochondria are very small organelles. You might find cells with several thousand mitochondria. The number
depends on what the cell needs to do. If the purpose of the cell is to transmit nerve impulses, there will be
fewer mitochondria than in a muscle cell that needs loads of energy. If the cell feels it is not getting enough
energy to survive, more mitochondria can be created. Sometimes they can even grow, move, and combine
with other mitochondria, depending on the cell's needs.
Structure
Mitochondria have two membranes (not one as in other
organelles). The outer membrane covers the organelle and
contains it. The inner membrane folds over many times
(cristae). That folding increases the surface area inside the
organelle. Many of the chemical reactions happen on the
inner membrane of the mitochondria. The increased
surface area allows the small organelle to do as much work
as possible. If you have more room to work, you can get
more work done. Similar surface area strategies are used by
microvilli in your intestinal cells. The fluid inside of the
mitochondria is called the matrix.
Using Oxygen to Release Energy
The matrix is filled with water (H2O) and proteins
(enzymes). Those proteins take food molecules and
combine them with oxygen (O2). The mitochondria are the only place in the cell where oxygen can be
combined with the food molecules. After the oxygen is added, the material can be digested. They are working
organelles that keep the cell full of energy.
1. Why are mitochondria called the “powerhouses” of the cell?
2. What determines the number of mitochondria that can be found in a cell?
3. How are the mitochondria different from other organelles in terms of its structure? What
advantage does this give the mitochondria?
4. How are mitochondria used in cellular respiration?