Powerhouses of Our Body: The Mitochondria
Did you know your body is home to around 100,000 trillion mitochondria? That’s right – these tiny powerhouses are everywhere, working behind the scenes to keep you going! But what exactly are they, and why are they so important?
In this blog, we’ll uncover the science of mitochondria and why they’re key to keeping you energized!
Mitochondria (singular mitochondrion), often called the cell’s powerhouses, play a crucial role in giving us the energy we need to walk, talk, breathe – basically, to live! Without enough energy from these tiny structures, our bodies would struggle to function. They’re key to keeping us going.
Structurally speaking, mitochondria are small, bean-shaped organisms found in most of our cells. They also have two membranes:
- An outer membrane
- A highly folded inner membrane
The folds in the inner membrane are called cristae, and they’re super important because they boost the surface area where energy production happens. Since mitochondria are all about making energy, you might be wondering: how did these little powerhouses come to exist?
Evolution of Mitochondria
There is a fascinating theory that describes how the mitochondrion originated…
A long, long time ago – around 1.5 billion years ago – the Earth was inhabited by very simple organisms. These organisms were composed of only a single cell as opposed to us humans who are composed of millions of the same. These simple single-celled organisms could not produce energy on their own. However, other similar tiny organisms like bacteria could and they did so very efficiently.
One day, the simple single-celled organisms decided to engulf or ‘swallow’ the energy-producing bacterium. However, instead of digesting the bacterium, the single-celled organism decided to host the bacterium instead (remind you of the movie, Alien?) The bacterium provided energy to the cell, and the cell provided protection and a place for it to live. Hence, both organisms helped each other out and developed what is known as a symbiotic relationship with one another. A symbiotic relationship is one in which both parties benefit. Over time, the partnership worked so well that the bacteria became a permanent part of the larger cell.
This is how scientists believe that mitochondria evolved. So, technically, the mitochondria in our cells today are the descendants of those ancient bacteria! They have changed over time, but they still produce energy for us, just like they did billions of years ago.
Now, how do mitochondria produce energy?
Mitochondria make energy by breaking down the food you eat through a process called cellular respiration. This produces ATP, which is like the cell’s energy currency. Now, let us understand the process of cellular respiration in more detail:
1. Breaking down food (Glycolysis): When we eat, especially carbs, the food is broken down into a simple sugar called glucose. Once inside our cells, glucose gets further broken down through a process called glycolysis. At the end of this process, we get lots of energy (in the form of ATP) as well as an end product called pyruvate.
2. Entering the Mitochondria (Citric Acid Cycle): Pyruvate then moves inside the mitochondria, where it goes through a process called the Citric Acid Cycle. This is a series of reactions that break it down further. The process produces a bunch of complex molecules including carbon dioxide (CO2), a little more ATP, and other high-energy molecules like NADH and FADH₂. Think of NADH and FADH₂ as “ATP’s buddies” – they all team up to create energy for our body.
3. Big Energy Production (Electron Transport Chain): These buddies of ATP then move into the Electron Transport Chain (ETC) (Figure 3), which is also inside the mitochondria. You can think of the ETC as a conveyor belt through which these ‘buddies’ move and release energy. This energy is used by a machine in our cells to produce tons of ATP.
4. Oxygen Involvement: As NADH and FADH2 move through the Electron Transport Chain, they get picked up by oxygen. This clears the way for more molecules to keep moving through the chain and making energy. That’s why oxygen is so important – it keeps the energy-making process going!
But there’s more – mitochondria don’t just make energy! They also help store calcium, generate heat, and control how our cells grow and multiply. So, do not get fooled by their tiny size! They are super important for many things in our bodies.
Conclusion
In short, mitochondria take the food we eat, break it down, and with the help of oxygen, turn it into energy that powers everything our body does. As Mitochondrial Biology Researcher Dr. Hemal Patel explains, the ability of mitochondria to produce energy efficiently is crucial for our health. Without properly functioning mitochondria, none of our body’s other processes would work well. In the next blog, we will underscore the importance of healthy mitochondria, and just how bad things can turn as these powerhouses lose their function.
