Mitochondria are tiny energy producers in every cell. One of many tiny structures floating in the cell’s cytoplasm (fluid) that are collectively called organelles, mitochondria are considered the most important of all cell parts, besides the nucleus.
Amazingly, mitochondria have their own separate DNA. You depend on them. They depend on you. And yet they are separate living organisms that have proved invaluable in tracking human history and evolution as well as for understanding cell operation. Their discovery in 1898 marked a great turning point for microbiology.
Englishman Robert Hooke discovered cells in 1665 when he turned his microscope onto a thin sliver of cork. As microscopes improved and grew in magnification power, scientists struggled to identify cells in other plant and animal tissue.
However, technical problems slowed their progress. More powerful microscopes were increasingly hard to focus and provided sharp focus on smaller and smaller areas. This was called “chromatic aberration.” In 1841 the achromatic microscope was invented and eased this problem.
Tissue samples had to be dye-stained so that individual cells (and parts of cells) would show up under the microscope. However, staining often damaged cells and masked the very cell parts it was intended to reveal. In 1871 Camino Gogli developed a staining process he called “black reaction.” This process finally offered scientists a chance to see the cell interior that lay beyond cell walls.
In 1781 abbot Felice Fontant glimpsed the nucleus of a skin cell. Scotsman Robert Brown named it the “nucleus” and, while studying orchids, was the one who discovered that the nucleus was an essential part of living cells. In 1891 Wilhelm Waldeyer discovered nerve cells.
By 1895 several researchers had actually watched cells divide through their microscopes and saw that a number of tiny structures (which they called organelles) existed inside each cell.
One of these researchers was Carl Benda, born in 1857 in southern Germany. Even as a youth, Benda had been fascinated by the microscopic world and was one of the first to call himself a microbiologist and to make a career out of studying the microscopic world. Benda had been swept up in the excitement of the effort to peer inside a living cell.
By 1898 it was clear that the cell cytoplasm (the internal fluid part of a cell) was not a simple, homogeneous fluid. Tiny structures floated in there doing no-one-knew-what.
During an experiment in 1898, Benda was able to make out hundreds of tiny bodies in the cytoplasm through the membrane of a cell. Benda thought they must be tiny pillars that helped hold the shape of the cell. So he named them mitochondria, from the Greek words meaning “threads of cartilage.” Neither he nor other scientists at the time gave mitochondria any significance other than that they existed and were part of the internal structure of a cell.
By 1910 scientists were better able to glimpse through cell walls and watch living cells function. Many scientists suspected that mitochondria provided energy to the cell. By 1920, scientists had determined that mitochondria were the power plants that supplied over 90 percent of all cell energy needs.
In 1963 it was discovered that mitochondria had their own DNA (called mDNA). This was a shattering discovery and made mitochondria one of the most important parts of a living cell. It meant that we are really cooperating colonies of microscopic bugs. In some far-distant past, tiny mitochondria organisms made a deal with bigger cells. They traded energy for protection. The mitochondria moved inside, but kept their separate DNA. That made these tiny substructures unique among all elements of a living body and an important subject for ongoing research.
But it all started with Benda’s discovery, even though he had no idea of the ultimate importance of what he discovered.
Mitochondria are called the “powerhouse of the cells,” where all cell energy is produced. That includes the energy for you to blink your eyes, for your heart to beat, or for you to perform amazing tasks like completing the annual race up the 1,576 steps of the Empire State Building. The current record holder is Belinda Soszyn (Australia) in 1996, with a time of 12 minutes, 19 seconds.
Imagine how much energy her mitochondria had to produce.