- [Voiceover] Proteins are gonna be the third
of the major macromolecules.
Now proteins are long chains of small subunits.
These individual subunits are amino acids.
What happens is, you can take multiple amino acids
and bond them together,
making long chains which can create proteins.
In total, there's 20 different amino acids,
so really that's not very many.
It all depends on how these amino acids are ordered.
You can create multiple different orders
to create many different proteins.
Now these amino acids all share some common traits.
Every amino acid has an amino end.
Well, that's your nitrogen side,
so you have nitrogen on the amino side.
Then you have your carboxyl end.
That's carbon double-bonded to an oxygen and then 0H.
And you have this R group.
The R group is referred to as the radical group.
That is the only difference
among all 20 amino acids.
They all have the exact same amino end,
the exact same carboxyl end,
but their R group will vary,
and that's what creates the differences.
Now these amino acids,
they're all joined together by peptide bonds.
So we know that your lipids were bound together,
we know that the carbohydrates were bound together,
but the bonds here have a special name.
So proteins are made from the building blocks amino acids,
which are held together by peptide bonds.
These peptide bonds, look at that,
they're produced by dehydration synthesis.
That means carbohydrates, lipids, and now proteins
all use this dehydration synthesis.
Remove water to make a bond.
So here are some of those amino acids.
Now if you kind of look and you go through
the non-highlighted portions,
you can see they're all C.
Then you have a bond of CO negative,
an NH3 plus, an H,
but the highlighted group,
that's the difference.
The highlighted group is what changes
from amino acid to amino acid,
because the actual base structure is always the same.
It just changes based on that R group.
And all these highlights are the R groups.
They can be as simple as glycine,
which is gonna be found on the right hand side.
It's the fourth one down.
So just a simple H, that's it.
Nice and basic and simple.
Or it can get as complicated as tryptophan.
That's on the left hand side four up.
You can see how that tryptophan has a whole ring,
then a bunch of other stuff.
That's a really complex amino acid.
More as a side note, have you ever heard of tryptophan,
maybe while making turkey at Thanksgiving?
Tryptophan is that stuff
that's in the turkey at Thanksgiving
that is naturally there, no problem there,
that's what makes you kind of tired,
a little drowsy there.
They have a lot of tryptophan.
Urge the body to take a rest, to take a nap.
So tryptophan, a little trivia there.
So here are how the amino acids are put together.
You see we have isoleucine and alanine are already bound,
but to create a longer chain,
the example here showing that valine needs to be added.
Well, to add valine, you'd better take off some water.
Two hydrogen and an oxygen are pulled off,
leaving the ability to bind,
forming a peptide bond.
And this'll keep happening over and over and over.
You just keep adding one after another
after another amino acid until the chain is long enough
to be the proper length to form into a protein.
So the only way to get a protein
is to have enough amino acids
put together in the proper order
to make a long enough polypeptide.
Polypeptides are just chains of amino acids.
Make a long enough polypeptide to form a protein.