If you want to make it through the day, you’re going to need some energy. In this lesson, we’ll learn about the organelle that supplies this energy, the mitochondrion, and why this cell structure appreciates the time you took to eat breakfast this morning!
Chemical Energy from Mitochondria
Your mother always told you to eat your breakfast. Breakfast is the meal of champions! It’s the right way to start your day when you wake up hungry, giving you the energy you need to tackle all your to-do lists. But while you’re feeding yourself, did you know you’re also feeding your cells?Your cells might not have the taste buds to appreciate the authentic Vermont maple syrup you put on your pancakes this morning, but they do appreciate the sugar. The cells in your body use the food you eat as a way to get the energy they need to get through the day.
They do this through cellular respiration, a process that converts food into usable chemical energy in your cells.Does your cell eat pancakes? Not exactly, but once the food is broken down by your digestive system, molecules from the food are transported to your cells for use. Many cells, including those in animals, fungi, and plants, contain mitochondria. Mitochondria are membrane-bound structures where cellular respiration occurs. Mitochondria is the plural form of the word mitochondrion. In these mitochondria, molecules from your pancakes are used to create chemical energy that your cells can then use to perform different activities in its daily routine.
For example, chemical energy allows active transport of molecules against a concentration gradient in the cell membrane.
A cell can have one to thousands of mitochondria depending on how much energy it needs. A cell in your biceps, for example, needs a lot of energy to pump iron and would have more mitochondria than a cell in your skin. You can fit a lot of mitochondria in one cell because they’re small, about the size of a bacterium. Bacteria, by the way, do not have mitochondria for reasons that we’ll talk about in other lessons.
Structure of Mitochondria
Mitochondria are composed of two membranes; both are phospholipid bilayers like the membrane around the cell. The outer membrane is a selectively permeable membrane that surrounds the mitochondria. This membrane comes complete with integral membrane proteins and pores for transporting molecules, just like the cell membrane.
The inner membrane of the mitochondria folds inward to form these extra surfaces for cellular respiration. In this way, the inner membrane creates more space out of a small area. It’s almost like having booths at a diner, giving customers multiple places to sit down for their daily breakfast special. Having 50 tables allows more people to dine in than if there were only 2 or 3 tables in the restaurant. Unlike the outer membrane, the inner membrane does not have pores or channels and is very impermeable.The cristae are the folds created by the inner membrane – or the restaurant booths themselves.
The surface area of the cristae can be several times larger than the perimeter of the mitochondria. Cells that need more energy can also have more booths, or cristae, for those reactions. The cristae contain proteins and molecules used for making chemical energy for the cell.
Finally there’s the matrix, which is the inside of the mitochondria created by the inner membrane. The matrix contains enzymes for cellular respiration as well as its own ribosomes and DNA needed to create some of the proteins important for this process.
In summary, many cells have mitochondria, or structures that convert food sources into chemical energy through the process of cellular respiration. The outer membrane surrounds the mitochondria. It is a semi-permeable membrane similar to the cell membrane. The inner membrane is impermeable. Its function is to create more space to perform cellular respiration.The folds created by the inner membrane are known as the cristae, which contain proteins and molecules that participate in cellular respiration. The matrix of the mitochondria is the space surrounding the cristae, which also includes molecules that participate in cellular respiration as well as ribosomes and mitochondrial DNA.
From this lesson, you will have the ability to:
- Describe mitochondria and explain their relationship to chemical energy
- Identify mitochondria structures