- [Instructor] What we're going to do in this video
is talk about proteins, and some of you all
might already be familiar with them,
at least in some context.
If you look at any type of packaging on food
you'll oftentimes see a label that has protein listed
and a certain number of grams per serving,
and some of you who might be athletically inclined
might associate it with things that help you build muscle.
And none of that is incorrect, but as we'll see
in this video and in many future videos,
proteins are involved in almost every, single
biological process and every, single living organism.
And if we ask ourselves what are they,
well, they're biomolecules.
They're molecules found in biological systems.
And they're large biomolecules.
We could call them macro molecules, molecules,
which is just referring to they're made up
of many, many, many, many, many atoms.
These right here are pictures,
two different views, of the chaperonin protein,
and this is, the chaperonin protein is roughly
800,000 times the mass of a hydrogen atom.
So it's going to contain tens of thousands
of atoms which would very much make it a macro molecule.
Now one thing to be careful of,
even though these are very, very large
on a molecular scale, even the largest protein
we know of, titan, is about one micrometer in length,
and that's much larger than this chaperonin here.
And a micrometer is one thousandth of a millimeter.
So even the largest proteins are microscopic.
Now another way to think about proteins
is what they are made up of.
So some proteins are made up of a single chain
of something called amino acids,
and things like chaperonin are made up
of multiple chains of amino acids.
So in a little bit I'll show you some particular
amino acids but for now just think of them
as the building blocks of proteins.
So let's say that's an amino acid
and then it will bond to another amino acid,
and it's not just one type of amino acid
and they can form these really, really, really long chains.
And so let me be very clear, this is an amino acid,
and it's called that because it contains an amine group,
which you don't have to worry about for now,
and they are the monomers that form the polymers
of what's known as polypeptide chains.
So these are monomers.
You connect them together, and you could keep going,
you could have hundreds or even thousands of these,
and so this whole thing right over here you can consider
to be a polymer, and a chain of amino acids,
the polymer of amino acids is known as a polypeptide.
Polypeptide.
And sometimes a polypeptide chain is a protein,
but sometimes a protein can be made up of multiple
polypeptide chains put together.
And what happens is after these amino acids connect
or bond to each other, they bend and they form the shape
of these proteins.
So you can imagine the chaperonin protein
right over here, it has these chains of amino acids
that bend, that have a conformation that form the shape,
and that's really what gives proteins their power.
And as I mentioned, proteins are involved
in almost every, single biological function.
They play a structural, structural role.
They play a mechanical role.
When your muscles contract,
you have actin and myosin proteins
interacting with each other so that your muscle contracts.
They can act as enzymes, which we will talk about
in a lot more depth in future videos.
Enzymes help catalyze reactions.
They help biological, biochemical reactions
happen in biological systems.
They can be involved with the immune system.
They could be involved with signaling.
They can send signals from one part of the body
to another, or they can be receptors on cells
that receive signals.
So proteins are incredibly, incredibly important.
Now with that out of the way, let's dig a little bit deeper
into the building blocks of proteins,
the monomers that build up the polymers
that are polypeptides, which could be proteins
or which could be used to build up proteins.
So what we see on the left here is a typical
structure of an amino acid.
Notice you see some oxygens, you see some hydrogen,
some carbons, and nitrogen.
And then bonded to this carbon right over here
you see this R.
And you say what element is that.
Well, this is not an element.
This is referring, this is kind of a placeholder
for a side chain, which differentiates
the common amino acids.
And you see some of the common amino acids in this diagram
right over here.
And you can see what the R would be.
For this arginine right over here,
that R group would be this part,
and you don't have to understand the biochemistry of it
in too much detail, but you can see
that they all have this top part in common,
but then they all have a different R group right over here.
And it's different sequences of these amino acids
that give us the diversity of all of the proteins
that we have in biological systems
of all of the various shapes.
And it really, really, really, really is amazing.
I mean, just going back to this picture of chaperonin
which is involved with helping other proteins
get their shape, it chaperones the protein folding process,
so to speak.
Just think about the complexity.
This looks like a complex machine,
but it forms naturally in biological systems.
And as we explore more and more biology,
we keep seeing these fascinating proteins that look like
these incredible systems that really boggle the imagination.