A Masterpiece of Evolution
Mitochondria are vital parts of our cells involved in numerous physiological processes. For example, they play a significant role in providing our cells with energy through a process called cellular respiration. In this process, they utilize oxygen from the air we breathe and metabolites derived from our food to produce ATP, the primary form of energy used in our cells. This makes mitochondria the foundation of all oxygen-dependent life on Earth. Mitochondria are not only crucial to maintain cellular function and health, but their dysfunction is a hallmark of ageing, which upon exacerbation can result in human diseases like cancer, neurodegenerative disorders (e.g., Alzheimer’s and Parkinson’s disease) and cardiovascular diseases. Hence, a sophisticated understanding of the molecular fundamentals governing mitochondrial function is an indispensable foundation for modern biomedical research.
The energy conversion process takes place inside mitochondria and is carried out by a sophisticated protein machinery: the respiratory chain. So why are we fascinated by this machinery? “Normally”, proteins are encoded in the DNA that is located in the nucleus. Indeed, the majority of proteins involved in the respiratory chain get produced in that way and need to be imported into mitochondria. But there is also a handful of proteins which are encoded by DNA that sits inside of mitochondria, which we call mitochondrially-encoded proteins!
– Fun fact –
Mitochondria originated as separate organisms (so-called endosymbionts) and were incorporated into our cells during evolution. Thus, they contain their own DNA!
The dual genetic origin of the respiratory chain
That means that the respiratory chain is encoded by two separate genetic systems: the nuclear and the mitochondrial genome. Thus, cells need to coordinate these two genetic systems, successfully produce all necessary proteins, bring them together inside of mitochondria and precisely assemble them into a functional machinery, that conducts energy conversion in sophisticated biochemical reactions - simply a masterpiece of evolution!