“Mitochondria are the energy source of the cell”
Does this sound familiar to you?
Childhood memories have faded away for most of us. While we remember the important details, the happiest moments of those days and the sad ones (if there were any), there must be a lot of things (mostly the math formulas and other lessons we learned in school) that we have forgotten. But what we will never forget is something we learned in biology class. It still remains fresh in our memory. Doesn’t it?
Are you feeling nostalgic yet? We are sure you are. This blog will take you on a journey and allow you to learn more about mitochondria. Let’s see how many of you still remember what mitochondria are and their functions in the body.
Brushing the basics
As you may recall, mitochondria, being the powerhouse of cells, provide them with energy. But there is more to them than meets the eye. Simply put, mitochondria have other functions to perform in the body.
Functions of mitochondria
The energy factories of the cell
Mitochondria break down nutrients and convert them into energy through a process called oxidative phosphorylation. This complex process involves a series of chemical reactions that ultimately produce ATP, the cell’s energy currency.
How do mitochondria produce energy?
The process by which mitochondria produce energy is a bit complex but fascinating. Here is a simplified description:
Glycolysis:
This first step occurs in the cytoplasm of the cell, where glucose is broken down into smaller molecules called pyruvate. This does not occur within the mitochondria, but is crucial for the following steps.
Citric acid cycle (Krebs cycle):
Once pyruvate enters the mitochondria, it is converted to acetyl-CoA and enters the citric acid cycle, where it undergoes several reactions and produces energy-rich molecules, such as NADH and FADH2.
Electron transport chain (ETC):
These energy-rich molecules then enter the inner membrane of the mitochondria. The electron transport chain is a series of reactions that occur across the inner membrane. Electrons are transferred through a protein chain and this transfer helps pump protons across the membrane, creating a gradient.
ATP production:
The energy of the proton gradient is used to produce ATP (adenosine triphosphate), which is the cell’s main energy currency. This happens in a process called oxidative phosphorylation.
Other functions
Cellular health:
Mitochondria also play a role in controlling the life cycle of the cell. They are involved in processes that regulate cell death (apoptosis), which is essential for eliminating damaged or unwanted cells.
Metabolism:
They help regulate various metabolic pathways and participate in the synthesis of certain hormones and neurotransmitters.
Stores calcium
Calcium is essential for a variety of cellular functions. For example, its release into a cell can trigger the release of neurotransmitters from nerve cells or hormones from endocrine cells. In addition, calcium plays a crucial role in muscle activity, fertilization, and blood clotting, among other processes.
Given its importance, cells strictly regulate calcium levels. Mitochondria contribute to this regulation by rapidly capturing calcium ions and storing them until they are needed.
Calcium also influences other cellular activities, such as control of metabolism, steroid production, and hormonal signaling.
Helps generate heat
When we are cold, we usually shiver to generate heat. However, the body has additional mechanisms for producing heat, one of which involves brown adipose tissue.
Mitochondria can generate heat through a process known as proton leak, which is part of non-shivering thermogenesis. Brown fat, which is more prevalent in infants (who are more vulnerable to cold), gradually decreases with age.
Mitochondrial DNA: A Unique Feature
One of the most interesting aspects of mitochondria is that they have their own DNA, separate from the DNA of the cell nucleus. This mitochondrial DNA (mtDNA) is inherited solely from the mother and contains genes important for mitochondrial function. It is as if mitochondria have their own set of instructions on how to function and replicate.
Final thoughts
Mitochondria may seem like a simple concept in our school science classes, but their function is anything but mundane. These tiny organelles are critical to our health, providing the energy our cells need to function and survive. So the next time you think of mitochondria, remember the critical role they play in our bodies.
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