[Felicia:] Or we could also describe you as short and me as tall --
[Caitlin:] Thanks a lot!
[Felicia:] -- because you can also describe protein molecules by their shape.
See what I did there?
Proteins are polymers.
They are long chains of smaller molecules called monomers.
[Caitlin:] Now where have I heard that before?
[Felicia:] Remember when we made a DNA molecule?
I said that DNA is a polymer that is made up of monomers.
[Caitlin:] And like DNA, the basic building block of polymers are linked together
through a covalent --
[Felicia:] or strong --
[Caitlin:] Right -- or strong -- bond that's extremely difficult to break.
[Felicia:] There is one really big difference though.
We built our DNA polymer using nucleotides as the building blocks.
But the building blocks for a protein are called amino acids.
There are 20 different amino acids. Think about it!
That's almost a full alphabet of amino acids!
[Caitlin:] Very cool!
But how are we going to encode that many amino acids with only four base pairs?
Isn't that like being able to spell all the words in the dictionary
by using just the first four letters of the alphabet?
[Felicia:] We'll find out how to decode DNA this week on... [Both:] DNA Decoded.
[MUSIC]
[Felicia:] Remember when we stuffed all of our DNA into the nucleus?
Well, the nucleus is only one compartment in a cell.
Let's see, if we think of the entire cell as a company,
each compartment is like a department that has a different function.
The furnace of the cellular factory is the mighty mitochondria.
It provides all the energy and power a cell needs to carry out its function.
[Caitlin:] I'm calling for a pause on all science related puns.
[Felicia:] And I'm ignoring that.
Moving on! The endoplasmic reticulum, is the production centre,
where proteins are made and synthesized.
The processing centre in this factory is the Golgi body, AKA the Golgi apparatus.
It's like the distribution centre. It helps to package, label, and
deliver proteins to the various departments of the factory.
[Caitlin:] Got it.
[Felicia:] So, you know how we keep saying that DNA's the blueprint of us,
the genetic information for constructing life?
Well, let's take a closer look at what that actually means.
The blueprints for building proteins are stored in our genes within the nucleus.
In order to actually build proteins, you have to send the blueprints
from the office down to the factory floor.
But our chromosomes are too big to make it out of the nucleus.
So, we need to use a messenger.
[Caitlin:] You mean Messenger RNA?
[Felicia:] Correct!
The blueprint for building a protein is copied, or transcribed, from the
DNA molecule into a short lived piece of messenger RNA, also known mRNA.
[Felicia:] That little mRNA has one job and one job only: to exit the nucleus and
carry the decoded DNA message to another compartment.
When it gets there, the blueprint encoded on the RNA molecule will be read and
a protein will physically be assembled.
[Felicia:] Right! Making proteins is a two-part process.
First, DNA makes RNA. That's called transcription.
And second, RNA makes protein. That's called translation.
This process is so important that it's called Central dogma.
[Caitlin:] Let's tackle that first part. Transcription: DNA makes RNA.
But, before we do, I feel like I need to nerd out a little.
[Felicia:] If you must.
[MUSIC]
[Caitlin:] Okay, so what is RNA?
Like DNA, RNA is a nucleic acid that is present in all living cells.
However, there are four main differences between DNA and RNA.
First, RNA only has one strand, not two like DNA.
Second, DNA is tightly packed in chromosomes within the nucleus.
Because it's so small, RNA can move in and out
of the nucleus into other compartments in the cell.
