Jung Tsai
The grueling complexity of the Krebs cycle has discouraged many bright students from pursuing medicine—I know this firsthand, as my own son was one of them! Yet, the story behind it is one of resilience. Hans Krebs, after being expelled from Nazi Germany to England, mapped the intricate chain reactions that produce ATP, the universal currency of cellular energy. His discovery earned him the Nobel Prize in 1953 and gave us the iconic phrase we all remember: “Mitochondria, the powerhouse of the cell.”
An Ancient Partnership:
Medical research has come a long way in the fifty years since I graduated from medical school. Today, mitochondrial studies are even surpassing nuclear DNA as the frontier of longevity science. Here are a few of the most fascinating “new” truths about these ancient organelles:The Original Immigrants: Roughly 1.2 billion years ago, mitochondria were independent bacteria that “invaded” our ancestral cells. Instead of a hostile takeover, they formed a partnership for mutual benefit. The so called symbiosis or endosymbiosis exists in an ecosystem of living environments. The Mother’s Legacy: They Cary their own circular mtDNA like bacteria which is entirely separated from the DNA in our nucleus and is inherited exclusively from our mothers.
A Living Network:
Mitochondria are not static blobs. They divide, fuse, and even “dance” between cells, traveling to where energy is needed most. Cellular Sentinels: Far more than passive batteries, they act as sophisticated sensors. They send and receive signals to maintain cellular integrity, manage detoxification, and balance the delicate scale between oxidants and antioxidants.
More Than Just Energy
Beyond making ATP: Mitochondria are master chemists. They help synthesize essential AMINO ACIDS,the building blocks like heme (for our red blood cells), myoglobin (for our muscles), and nucleotide (for DNA), glutamate (a vital neurotransmitter). When these “life machines” malfunction, the consequences are widespread, contributing to Type 2 diabetes, heart disease, depression, neurodegenerative disorders, and even chronic fatigue. In short: without healthy mitochondria, a healthy lifespan is impossible.
The Metabolic Battle:
The relationship between cancer and mitochondria is particularly revealing. In the Krebs cycle, a healthy cell produces 32 molecules of ATP from one molecule of glucose. Cancer cells, however, are notoriously inefficient. They switch to aerobic glycolysis (Otto Warburg effect who was award Nobel Prize in 1931) producing only 4 ATP per glucose molecule.
Because this process is so inefficient, cancer cells must consume massive amounts of glucose to survive—a hunger we can actually see on PET scans. In a startling 2022 Harvard study, researchers found that cancer cells act like “energy vampires,” reaching out with tiny nanotubes to steal mitochondria from our T-cells (immune cells), causing them to die prematurely（photo). In the similar studies they also demonstrate that the breast primary cancer growth needs glucose, but when tumor metastasize to lung it used pyruvate and to brain it used glutamine instead. By focus on Krebs cycle of the cancer’s mitochondria we may offer the fight for metastatic cancer.
The Future of Health-span:
As we age, our mitochondria become “exhausted” from decades of multitasking. They are the ultimate deciders of whether a cell should live, divide, or undergo programmed death (apoptosis). Because they sit at the very center of the hallmarks of aging, better caring for them is our most direct path to longevity.
Healthy mitochondria equal a healthy life. In our next discussion, we will dive deep into how we can support these ancient partners so they can continue to support us—extending both our lifespan and, more importantly, our health span.
<2026-04-15>