DNA, the genetic code of life
DNA, the genetic code of life

DNA is the organic software of almost all living things, and each individual cell is the hardware on which this genetic software is run. This amazing code, DNA, is the subject of one of Udacity’s newest courses launching this fall, Tales from the Genome: Adventures in DNA, Identity, and Health. This is an introductory course that will teach you basic genetic principles, regardless of your academic background. Together with the personal genetics service 23andMe, we will explore the biology of the most important code in your life: the human genome.

Most Udacity fans already appreciate the beauty of code, and most of you are likely to be far more expert at understanding and manipulating computer code than I am! (Although I am pleased with my progress so far in CS101). Still, I am continually surprised by how unfamiliar people are with their own personal genetic code wrapped up inside every cell of their body. Long before transistors, binary code, or the Internet, mother nature built her own coding system for all life on our planet. This code of life, billions of years in the making (Carl Sagan would be proud), is far messier, more dynamic, exceedingly more robust, amazingly more efficient, and absolutely more imperfect than man-made code.

Tales from the Genome will give you a taste of this complexity and begin to reveal exactly how much code is necessary to run a whole human body:

  • Just as there are two possible values in binary code (0 and 1), DNA (the code of our genomes) has four possible values (A, T, G, or C).
  • A single line of DNA code is always paired with another that can be inferred from the first: you may have heard of this before, DNA is almost always two strands that pair together in a regular way (the double helix).
  • One copy of the human genome is 3 billion pairs of code letters, so 6 billion actual code letters total; and each cell has two copies of the genome, so that’s 12 billion letters per cell.
  • Approximately 50 trillion cells in the human body means that you have approximately 1 yotta of DNA code letters. That’s 1,000,000,000,000,000,000,000,000 letters of code! If we think of one letter of DNA code representing one bit of information in computer code, then that’s equivalent to about 100 zettabytes of hard disk space. That’s more than 10 billion times more information available on today’s 2 Terabyte hard drives!

Somehow all of the DNA you have is wrapped up and organized inside your cells (and it doesn’t just sit there)! It is actively read all the time, even while you eat, sleep, and poop; every cell is reading different parts of the code, which makes that cell unique and allows it to do its job as a skin, stomach, blood, or brain cell. There are thousands of different cell types working together to make up who you are: one conscious being with specific traits and desires, a singular intelligence and personality. But at the root of it all, you are a giant conglomeration of cells all meticulously reading the genetic code to keep you alive and functioning, forming the basis of all of your traits. Tales from the Genome will show you how to connect your genome to your traits and reveal what it really means to be human. We will explore the personal stories of people living with a variety of traits, from lactose intolerance to dwarfism to breast cancer to bipolar disorder. We will learn about how the genetic code controls these traits and what impact these traits have on individuals, their personal relationships, and society at large.

When you sign up for Tales from the Genome you will acquire a basic understanding of how this organic code of your genome is turned into flesh and blood. To hear more about the course and get updates on its launch in the fall, visit the overview page and click “Take the Class” to enroll. I hope you will join us on the adventure, and maybe you will find out the secrets your genome holds.

Matthew Cook
Course Instructor