For some reason students rarely seem to get excited about cell biology, a class that is typically required for anyone entering into the field of health care. In the cell biology course that I teach, to help perk up interest in the cellular world, I start the semester off with a little story about why cell biology is, in fact, your own gripping drama. The story of your body goes as follows:
* The Cells that Make Up ‘You’ *
Every living thing is made up of cells, or at least a single cell. Your body is composed of trillions (i.e. a million million) of cells working hard, 24/7 to keep you in working order. Each and every one of your cells contains a complete genetic DNA blueprint of ‘how to make you’ as well as all the cellular machinery required to run the show.
* Your Body’s Guests & Interlopers *
Your body is also host to other species. ‘Good guy’ bacteria cooperate with your body to help you digest your food, make Vitamin K and crowd out the bad guys. Demodex mites may be dwelling in your eyelashes as you read this. Ladies, yeast (Candida) are always lurking, just waiting for an opportunity. When your natural flora (good guy microbes) gets knocked out of balance, such as when you take antibiotics, these eukaryotic invaders can quickly multiply and give you a nasty yeast infection. These are just a few examples. Your body is like a living planet filled and covered with many, many different organisms.
* The Immune System: Your Body’s Police Force, Secret Assassins & Cell Death *
In addition to your body’s own ‘average Joe working cells’ you are internally patrolled by a microscopic police force, the cells and molecules of your immune system. These cellular cops are constantly on the lookout for bad guys, identifying interlopers and eliminating them.
Sometimes pathogens get into your cells and the only way to get rid of them is for the infected cell to be destroyed. It is the job of T-cells, the cellular assassins of our immune system, to convince defective or infected body cells to kill themselves, to self-destruct (apoptosis).
Bad guy microbes (pathogenic prokaryotes, eukaryotes & viruses) are everywhere. You can’t avoid them, and your body’s police force is constantly intervening to prevent you from being colonized by pathogens. Your skin, sweat and oil (sebum) are elements of the external fortress that help prevent pathogens from even getting inside you in the first place.
* Your Cells Even Contain Fossils! *
The cells of ‘planet body’ also contain fossils. That’s right! Within your DNA are proviruses, the genetic material of viruses that have infected you and those that have infected your ancestors. This viral DNA has been incorporated into your human DNA and passed down from generation to generation. Estimates are that approximately 1/12 of the DNA in each of your cells is viral, fossil viruses not you.
Cell biology is a far cry from boring. It is your very own microscopic drama that is being played out everyday, all day, for as long as you live!