- So I have drawn four different
triglyceride molecules over here.
And some of you might be saying,
"wait I thought triglycerides they involve
"all of these carbons and hydrogens and oxygens".
Well I see the oxygens over here
but where's all of the carbons and hydrogens?
And my answer to you is that they will be implicit.
This is a short-hand way of diagramming out
these large molecules.
And you'll see this many times
when you take chemistry, biology, organic chemistry.
And what's happening here is that
each of these pointy parts of this chain,
each of these vertices there's implicitly a carbon.
There's a carbon there, there's a carbon there.
There's a carbon there.
And there's also,
if we don't put a letter at the end of the chain,
there's also a carbon right over there.
So implicitly there's a carbon there,
there's a carbon there, there's a carbon there.
Now you might also be wondering
what about the hydrogens?
Well we assume that every carbon has four covalent bonds.
And so if there's extra covalent bonds
for each of these carbons,
we assume that those covalent bonds are with hydrogen.
So for example, this carbon right over here,
it has two covalent bonds.
So the other two covalent bonds must be
must be with hydrogens.
Same thing for this carbon right over there.
It must be bonded to two hydrogens.
This carbon, the way its drawn, we only
explicitly see one covalent bond.
So there must be three covalent bonds.
There must be three covalent bonds to hydrogens.
So the carbons and hydrogens are all there.
They're just implicitly there.
Now you might notice, and actually, if you don't notice,
I encourage you to pause
and think about what the difference is
between this triglyceride, this triglyceride
this triglyceride and that triglyceride.
And it might jump at you pretty quickly.
What jumps at you is this triglyceride has
no double bonds.
This one has one double bond.
This one has several double bonds.
And this one also has several double bonds.
But these two are also different
and we're gonna think about the way that they're different.
You might immediately see that this one
kinda kinds and curves
while this one is able to stay relatively straight.
And actually that is the main difference.
And we're gonna talk about it in a second
why that is.
But first lets talk about this one.
When you have all single bonds
one way to think about it is that
you have put as many hydrogens onto
these carbon chains as you can.
Or another way of thinking about it is
we have saturated this fat with hydrogens.
And that's why this is called a saturated fat.
A saturated, this is a saturated fat.
This is something that you might have heard of.
This is referring to things like butter.
They've a lot of different fats that we tend to
associate with being solid at room temperature.
And the reason why they're solid at room temperature
is because this are all bonded to these hydrogens.
There's no kinks for them to do to the double bonds.
These are able to be relatively dense.
Which allows it to be solid
or typically solid at room temperature.
And these are sometimes associated with,
I don't want to get into the whole nutritional battles
about saturated fat and fat's good or bad.
But these are sometimes associated
these are sometimes called your bad fats.
But as we'll see they aren't the worse fats.
The worse fats are actually this one right over here.
But we'll talk about that in a second.
So this is saturated fat because a way to think about it
is it's saturated with as many hydrogens as possible.
Now this one of the right,
and I don't know anything about it
it has all single bonds.
Now over here, or all single bonds between the carbons.
Over here we see a double bond.
We see a double bond between that carbon and that carbon.
And because of that,
this carbon already has three covalent bonds
so it's only gonna be bonded with one hydrogen.
This one already has three covalent bonds
so it's only gonna be bonded with one hydrogen
as opposed to two like these characters over here.
And because of that we don't have
as many hydrogens on the chain as possible.
So we consider this to be an unsaturated fat.
Unsaturated fat.
We don't have as many hydrogens as possible.
And because of that unsaturated fat,
and specially polyunsaturated fats,
these double bonds they tend to form
these kinks in the structure
which keep the molecules from getting really, really dense
which tends to make them liquid or more likely to be liquid
at room temperature.
So this is an unsaturated fat.
This right over here, we have multiple,
we have multiple double bonds in play.
This is called a polyunsaturated fat.
Polyunsaturated fat.
And since this actually only has,
they're both unsaturated fats.
This is a polyunsaturated fat.
And since this only has one double bond
we can call this a monounsaturated fat.
So these are both unsaturated fat.
This is many times happening so poly.
This is happening once, so we call it monounsaturated fat.
Now one question you might have is
why are the kinks forming for
this molecule and this molecule.
And why are they not forming with this molecule
even though this one has double bonds as well.
And this goes to our good friends
cis and trans.
And so you might remember,
if you have a double bond between carbons.
And lets say that you have,
lets say that you have one configuration.
Let me just do it this way.
Lets say you've one configuration where
this is attached to some type of a carbon chain,
and lets say that this is a hydrogen.
Then on the other side the rest of the carbon chain
it could be in one of two configurations.
The rest of the carbon
the rest of the carbon chain could
be on the same side as the carbon chain on the left.
So I'll put R' there.
And, let me do that in the same color.
So you have your hydrogen.
So this is one configuration.
Now another configuration would be
carbon double bonded to carbon.
You have your hydrogen but now the hydrogens
are on opposite sides.
And your chains,
the rest of the carbon chains
are on opposite sides.
And as we talked about before,
this is because double bonds are rigid.
You can't rotate around it.
So it matters, these are actually different,
these are actually different isomers right over here.
Depending on whether this chain is on
the same side as this chain.
Or whether is on the same side.
When it's on the same side
we call this a cis configuration
and this is a trans, trans configuration.
And it turns out that most naturally
produced unsaturated fats are in the cis configuration.
And because they're on the cis configuration
whenever you have these double bonds,
it forms, it makes the chain actually bend.
And if you have many of these double bonds
it makes it bend a lot.
And so polyunsaturated fats are even more
likely to be liquid because it's very hard to pack them.
So what's going on over here?
Well these are actually the configuration
where the, I guess you could say,
the rest of the carbon chains
are on opposite sides of the double bond.
Notice this carbon chain it might be
a little bit hard to see
is above the double bond.
We formed a covalent bond going upward there.
While this carbon chain,
right over here, is below the double bond.
And because of that it doesn't form a kink
and these are in the trans configuration.
And so this right over here,
this is called a trans fat.
This is called a trans fat.
And they aren't typically found,
they aren't typically found in nature.
Now it's interesting about trans fats
is a lot of folks say "hey you know, okay,
"maybe saturated fat is bad for us.
"Maybe we shouldn't eat as much butter and all of that".
And some of that's even up for debate these days.
And they say, "what if we started with unsaturated fats?".
Which are typically viewed as more healthy,
our polyunsaturated fat.
And were just throw a bunch of hydrogens on them,
may be not to fully saturate it,
but enough hydrogen so that some of these
double bonds disappear.
And so it's more solid at room temperature which
might make it a good replacement for butter in cooking.
And a lot of the shortening that you might have seen
even 10, 15 years ago, or even today in a lot of places,
they're essentially trans fat.
And so what happened is is that,
yes, you can replace a lot of these,
you can start to saturate it more with hydrogens.
But that process also turned some of the
cis double bonds
into trans double bonds.
And at first people said, "oh that's harmless,
"this is probably good for you, it's still unsaturated".
But it has some of the properties of a saturated fat.
It's nice and solid and buttery and all of that.
And maybe is even cheaper to produce.
You can take it from other oils.
But it turns out that this is very unhealthy.
There's a lot of debates in nutrition,
but this is unequivocally unhealthy.
This does not exist in nature
and it has all sorts of bad impacts.
And that's why a lot of states, and even countries
have now banned trans fats.
They actually, I've even heard people
go so far and say "this is actually poisonous
"to your body" in certain ways.
And it really affects you in extremely negative ways.
That might be extra strong language
but I'm, I guess I'm trying to scare you a little bit.
Don't eat trans fats.
Anyway, hopefully you enjoyed that.