In 8th grade, you learned that the mitochondrion was where oxidation and the Krebs cycle took place. You learned that this was the cell's power plant. You imagined a tiny car engine burning gasoline.
In high school you memorized the Krebs cycle, took the Biology Advanced Placement Exam, and managed to slip into a decent college. You slogged through biochemistry. You eventually became a pharmacist.
Mitochondria reside in our cells--they are sort of us, but not exactly--they carry their own DNA, and they descend from (mostly) your mother. And her mother. And her mother. You may have heard that from a teacher trying to get you excited about cell organelles. Coloring them was about as exciting as they got.
Too many teachers confuse science with fact.
Three decades ago I sat in the auditorium of the American Museum of Natural History. The teacher had primed our class, so when the serious man at the podium asked what energy was, I knew the right words. I half-raised my hand. The serious man looked over at me. I started to open my mouth—I knew the words, my teacher already started to smile.
I did not say them. I shook my head slightly, then looked down at my feet. “The ability to do work.” The words explained nothing to me, and still do not. My teacher was disappointed—usually enough motivation to make me answer a stranger’s question.
I stopped trusting words.
Oxidation involves transferring electrons--energy, “the ability to do work,” is involved.
Oxygen combines with fuel to create heat and light. If it happens quickly--fire. Oxygen is consumed, and flame and water and carbon dioxide are released.
It can happen slowly--the rusting rims of your child's bicycle left out over winter warms the frigid air as metallic iron morphs into ferric oxide. Heat is released, slowly. Molecules vibrates as electrons shift. I know the words. I still do not trust them.
The warmth and movement of your love come from the sun.
You twist together, heat and motion.
In the morning, the sun rises again. The apple pie she ate last night courses through her veins as sugar, and the sugar feeds the mitochondria. Heat, water, and carbon dioxide are released. As she steps outside into the chill, you see her breath. The water vapor dissipates, and will, eventually be released as rain. The carbon dioxide will eventually feed next spring's garden, and a few molecules may indeed end up in the blossom of an apple tree, as the sun's energy restores a bit of order. You make up your shared bed, laughing at the entropic knot of sheets and blankets.
The heat from your body comes from mitochondria. Trillions of symbionts stoking our fires. The work of shifting electrons produces free radicals and peroxides, fiercely reactive compounds that can distort strands of nucleic acids. Each mitochondrion carries several copies of the same (relatively) simple chromosome, to ensure that a working copy remains among the ashes.
If the soul rests anywhere, it rests in the mitochondria. After the last agonal gasp, the body cools quickly--the surface of the corpse quickly approaches ambient temperature. The change is startling, even to my experienced hands. But the mitochondria are only half the story.
Mitochondria are thought to have the same common ancestor as chloroplasts. Both alter states of energy. The chloroplast uses sunlight to create "stuff" from carbon dioxide and water. A mature oak tree weighs tons, all but a few pounds derived solely from carbon dioxide and water. The "stuff" of flour and apples and sugar in the pie last night all from chloroplasts. The turkey last night fed on this "stuff," the chair you sit on, the tar in the shingles over your head, all from this "stuff." The oil in the ground, the coal powering your electricity, all from the same "stuff."
The best part of science gets buried in the details:
Nicotinamide adenine dinucleotide.
Adenosine triphosphate.
Alpha-ketoglutarate pathway.
My high school students yawn at the details. I try to use a three-dimensional model. The nitrogen atom is represented by a blue wooden ball. “The red balls are oxygen, the blue balls.…” My frontal lobe edits a little too slowly today. I have their attention now—blue balls they know, and the room now vibrates, a different kind of heat.
The chloroplasts, like mitochondria, make their own DNA, separate from the organism it inhabits. Both transduce energy. Both descended from a primitive bacteria, prokaryotes, and both now use modern cells to play their game. One captures energy in organic bonds, the other releases it. Carbon provides the backbone, and water the electrons. They did this before we were conscious, before anything was. And they will do it until the sun stops.
And here is where dharma enters the classroom, but not in the strictly religious sense. Creationism rests on faith. There may be something to it, but it is not science, even if the state of Texas requires biology textbooks to mention it.
Dharma comes from the Sanskrit root dher-, "to hold firmly, support." It is an Hindi word, and it is a good one. We have a similar word, "religion," but religion may be too narrow. Evolution requires dharma.
I breathe. I eat. I make an apple pie from fruit picked by energy released by my sister's mitochondria. My lover snuggles against my warm, full belly. In the morning, I see my breath against the morning chill, the sun warming my face. Water and motion and carbon dioxide and warmth. By the spring, my sister will rest next to a tree on a hill overlooking her favorite place in the world, Keeney Orchards. The carbon dioxide and water vapor of my sobs will someday form more stuff in a chloroplast not so far away, molded together with the energy of the sun.
Science. And grace.
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