The powerhouse
Folded membranes make more energy.
Fitting more in a box
If you fold a long cloth, it fits in a small space but its surface is still large.
Why might a mitochondrion fold its inner membrane?
What this lesson covers
The idea
Mitochondria, the cell's powerhouses, have a smooth porous outer membrane and an inner membrane folded into cristae that increase surface area; there, cellular respiration breaks down glucose and other molecules, storing the energy released as ATP, the cell's energy currency.
Fitting more in a box
If you fold a long cloth, it fits in a small space but its surface is still large.
Why might a mitochondrion fold its inner membrane?
- To get more surface for reactions in a small space
- To make the cell bigger
- To hide from the nucleus
Fold the membrane
Slide the number of folds. Watch the surface area change.
Mitochondria and ATP
Mitochondria are the cell’s powerhouses. Each has a smooth, porous outer membrane and an inner membrane folded into cristae, which increase the surface area for chemical reactions. In cellular respiration, glucose and other molecules are broken down, and the energy released is stored as ATP, the cell’s energy currency.
Mitochondria have two membranes. Almost all cell activities use ATP.
- Part | Feature
- Outer membrane | smooth and porous
- Inner membrane | folded into cristae (more surface area)
- Job | cellular respiration: release energy and store it as ATP
Notes
Mitochondria: the powerhouses. The inner membrane is folded into cristae (more surface area). Cellular respiration breaks down glucose and stores the energy as ATP, the energy currency.
Check yourself
Mitochondria are called the “powerhouses” because they…
Cristae are…
ATP is the cell’s…
Cellular respiration breaks down glucose and other molecules to…
- supply the energy most cell activities need — correct. Yes.
- store water. Vacuoles store water.
- make proteins. Ribosomes do that.
- finger-like folds of the inner membrane — correct. Yes. They increase the surface area.
- folds of the outer membrane. The inner membrane is the folded one.
- storage sacs for starch. Starch is stored in leucoplasts.
- energy currency — correct. Yes. It is used for most cellular activities.
- DNA. DNA stores genetic information.
- wall. ATP is a molecule, not a wall.
- release energy, stored as ATP — correct. Yes.
- make a cell wall. Respiration releases energy.
- build new DNA. It releases energy.