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Helping you navigate life in the age of biotech
In the age of biotechnology, we are surrounded by the fruits of modern genetic technologies, from GMOs, to mRNA vaccines, biotech medicines, and consumer genetic testing. To become an empowered, educated consumer, learning about your DNA is a great starting point.
Today, we’ll demystify DNA and explore how it makes us who we are. We’ll also tackle three areas rife with myths and misconceptions: (1) genes vs destiny, (2) person-to-person variation, and (3) foreign DNA.
We’re going to be covering a lot of ground, so get comfortable, take your time, and go easy on yourself if you’re feeling a bit lost at times.
What does DNA do?
Your DNA is like a cookbook with recipes for how to make you and keep you alive, from conception to death. This “cookbook” also contains information on where and when to cook each recipe.
Your DNA contains roughly 20,000 genes, which you can think of as recipes for how to make a protein. Proteins are the workhorses of cellular life - they do much more than give you big biceps! In addition to 20,000 genes that code for proteins (protein “recipes”), our DNA also contains lots of other information, including regulatory units that control when genes are “turned on” (ie. when the recipe is made) and recipes for special RNA molecules. It also contains a lot of information that we don’t yet understand (is it evolutionary junk, or functional?).
You have two cookbooks inside each of your cells - one from each biological parent. Typically, both recipes get used. In other words, if it’s time for pancakes, your body makes Mom’s pancakes and Dad’s pancakes (note: the recipes are usually very similar, if not identical). In scientific terms, this is called “bialleic expression” (both alleles). There are plenty of examples of “monoallelic expression”, X-chromosome inactivation and the colouring of tortoiseshell cats, but this is not the default. Read more here!
There are some exceptions to the two-cookbook situation. Sperm and eggs only carry a single new-edition “fusion” cookbook, poised to pair with another cookbook, and create a unique child. Also, mature red blood cells have no DNA because they ditch it in order to make room for more hemoglobin.
What makes your hair, heart, lung, and skin different is the subset of recipes they are cooking - the genes they are “expressing”. In other words, every part of your body has the same cookbook, but serves a different buffet. Likewise, your body changes which genes (recipes) it uses based on the internal and external environment (e.g. temperature, food, hormones, stress, food).
It’s remarkable to consider that inside each cell, your DNA is guiding the many processes that keep us alive, developing, and interacting with our environment. Information is constantly flowing from DNA, to RNA, to protein, a process known as the “central dogma” of biology. This process is happening in thousands of genes inside trillions of cells at all times.
What is DNA made of?
DNA is a remarkably simple molecule. It’s a long double-stranded chain made from four units, called nucleotides. These four units are usually abbreviated A, T, C and G. In the cookbook analogy, this means your recipes are written in a 4-letter alphabet.
Within a gene, each three units of DNA is called a “codon” and specifies which amino acid - protein building block - to add to the growing chain. The final chain of amino acids is then shipped off to do its job. This work inside your cells is done by tiny little translators which read from an RNA copy of your DNA. The code that translates the language of DNA (and RNA) into proteins is called “the genetic code” and is pictured below.
When scientists discovered that humble DNA was the “transforming principe” - that it held the instructions for life and passed them on from one generation to the next, they were baffled. How could such a simple molecule, with only four subunits, create such complexity? Learn more here about the discovery of the role of DNA in 1944 and about the cracking of the genetic code in the 1960s.
How is DNA organized and stored?
Your complete DNA collection (cookbook) is called your genome. In humans, the DNA is organized into 23 pairs of chromosomes. You can think of the 23 chromosomes as chapters in your cookbook. As mentioned earlier, we each have two slightly different cookbooks within us - one from each biological parent.
Within your cells, most of your DNA is tucked away in a walled fortress (sphere) called the “nucleus”. To enter or exit the nucleus, molecules must pass through a special hole called a “nuclear pore”. These pores are guarded by “bouncers” that decide who can and cannot enter - a ticket is required! A small amount of DNA is stored inside your mitochondria (mtDNA), which comes from your biological mother.
Every organism on the planet uses DNA in the same way - from animals, to plants, to viruses, and bacteria. It’s all made from the same A,T,C,G subunits and is all converted to protein using the same genetic code. This is why we can insert human genes into bacteria or yeast to make them crank out medicines (like human insulin).
Myth 3: Foreign DNA. One of the biggest myths about DNA is that we should worry about foreign DNA. In fact, we eat DNA all the time - it’s in every plant and animal food that we consume, from apples, to lettuce, to nuts, cereals, and hamburgers. If it was alive, it contains DNA - lots of it! The DNA in our food gets chopped up into tiny little bits, the same building blocks of our own DNA, and is recycled into various molecules inside us. It does not sneak inside our cells, jump into our DNA, and turn us into the food we eat. It’s a similar story for foreign RNA (a topic for another post).
That said, there is one context in which fear of foreign DNA is appropriate: live viruses. Certain types of viruses can enter our cells and integrate their DNA into ours using sneaky tricks. Fear of such viruses makes sense, whereas fear of DNA in foods does not!
The Bottom Line
Isn’t DNA amazing?! Those four little letters - A,T,C,G write the cookbooks for me, you, and all living organisms. Those cookbooks are being used in trillions of cells inside you at every moment. It boggles the mind!
I hope this article helped you feel more informed and empowered to navigate the many genomic technologies that surround us, from mRNA vaccines, to GMOs, gene therapies, and direct-to-consumer testing. The field of genetics is far more complex than I can do justice to in a blog post, but the concepts we covered are powerful pillars to build on.
Thanks for taking the time to educate yourself. Please spread the word and help others build up their knowledge. To learn more, check out my related podcast episodes and recommended resources.
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