And it's now still used, even though as with many dogma,
it's not an absolute dogma.
But the central dogma of biology, or molecular biology,
says that Information flows in a single direction from your genome,
that is your DNA, to RNA, to proteins.
And the processes that govern that we give different names.
So the copying, when DNA is turned into genes, the first step is you take pieces
of it called exons, and you transcribe them, that's the copying process,
into RNA, and RNA is essentially an exact copy of the DNA where all the letters
are the same with the only difference being the letter t, or
thiamine becomes a letter u, which is uracil.
But otherwise it's molecularly the same thing.
That RNA then has to be turned into a protein.
Now, proteins are not comprised of these four letters of nucleic acids.
They're comprised of 20 letters that are called the abbreviations for
amino acids and proteins are also long molecules, not nearly as long as DNA.
A typical protein might be 300 or 400 amino acids long,
and the way you get a protein is you take a piece of RNA and
you read it three letters at a time, and each triplet encodes an amino acid.
And if you think about it for a second there's four possible RNA nucleotides.
So there's four to the third, or 64 possible combinations.
Each of those 64 triplets each gets
translated either into amino acid or not.
There's three special ones called stop codons.
They indicate the end of a protein.
So that's basically how DNA goes and becomes a protein.
And the proteins kind of do all the work of your cells.
So the proteins in your body are what are actually doing most
of the functional work of say, metabolizing things,
digesting your food, moving things around in the cells.
So that fundamental dogma has been around for many decades now, and it more or less
describes how information flows most of the time from your genome to two proteins.
However, that's not the whole picture, we now know.
So over time, we've learned that information can flow the other way,
and as scientists got more familiar with the whole model,
they realized that it had to form the other way.
As I was saying a little earlier in this lecture, there are many different cell
types in your body, every cell has the same exact DNA.
So if everything just flowed from the DNA to the proteins,
it would seem sort of fundamentally impossible for the cells to
behave differently, yet we know that neurons don't act like skin cells.
So what's going on?
So the proteins themselves, some of the proteins that are created by the DNA
go back and bind to that DNA stuff and modify it and
change the genes that get turned on and off.
So proteins can self regulate in this way.
And there are other things that can happen with DNA, other modifiers,
some are called methylation marks that can change DNA as well.
So there are features on the DNA that are affected by the proteins themselves.
So this feedback loops in the process in this sort of information flow, and
that as a result, information's actually flowing backwards.
So in the genomics field, so
how do we make these measurements that I'm talking about?
How do we measure if you want to understand cancer, then we have to go and
get some cancer cells and figure out what mutations happen in the cells.
So how do we do that?
Do that with sequencing.
So sequencing is sort of at the heart of genomics, and
the genomics revolution that we've been in for about the past 20 years, and
this really accelerated over the past ten years.
And one reason for this acceleration is that genome technology has gotten
incredibly fast and efficient.
So what you're looking at here are some of the latest sequencing machines.
A sequencer today, the highest super sequencer we have today can sequence in
a single run of the machine, as many as a trillion nucleotides of DNA.
So to give you a sense of what that means, the Human Genome Project was started
in 1989 with the goal of sequencing one human genome in 15 years.
It beat that goal, we actually published the human genome in 2001, so
in just 12 years we finished the project.
I was part of that project.
And it was a massive effort involving thousands of scientists
from around the world.
And sequencers were employed at