- Now we have
these funky players
that we haven't really
been introduced to yet,
and they are electron carriers,
and electron carriers are
really,
really important.
Now, you can think of
an electron carrier as a car,
and this car has a name,
it's NAD,
and right now NAD is not
carrying any electrons.
But if we add two electrons
into this mix, NAD becomes NADH,
and, I don't know,
maybe I
should try to give it a slightly
different color to show that,
now, it is a high
energy electron carrier, NADH,
and these electrons are
literally attached to it now.
How cool is that?
Okay.
Who cares,
except those high energy
electrons, let's make
a note of that.
These guys, they're not
normal electrons.
They're like super
power electrons.
They're high energy electrons.
And I'm happy to talk to you
about why they're high energy,
like it really is a real thing.
I think about them as just being
like these little rock stars
that bounce around really high,
and they have a lot of
kinetic energy kind of,
like sort of, the way
that I think about it.
But I can explain to you how it
really is if you
really want to know,
but I'm cool with you just
accepting that
they're high energy.
And NAD, it's actually NAD+,
is empty.
It's not carrying any
high energy electrons.
If we add some high energy
electrons to it, now it's NADH,
and it can take those
high energy electrons and
basically cash them in for ATP,
which think about
that for a second.
We know ATP is an important
molecule for living systems,
we know it's basically
the energy currency
for our whole existence,
and if the NADH, the high
energy electron carriers,
can cash in those
electrons for ATP,
Dude, that's magic.
There are multiple high
energy electron carriers.
There's another one called FAD,
and FAD turns,
if it's carrying two
high energy electrons,
it becomes FADH2.
In fact, the actual breakdown
of the molecule itself is
not as important to me as
you knowing that two high
energy electrons can be
carried by this molecule
and those will come in
handy in our whole process.
I think it's worth
taking some time like
to talk about ATP a little bit.
ATP is an adenosine.
Adenosine, that's the "A,"
triphosphate.
There's three phosphate
molecules attached
to the adenosine,
and it doesn't take
a whole lot of energy to
break off that phosphate,
the terminal end phosphate,
and get a P+ ADP.
Look at what I'm doing here,
and I'm just drawing
it backwards,
Adenosine, and that's
Adenosine diphosphate.
Let's write that down.
ADP, ATP, and I just drew it out
for you so that you could see
the chemical bonds that are
important in this process.
If you break the chemical bond
between the third phosphate
and the second phosphate,
this little, lonely
phosphate now,
this guy right here,
is going to form a powerful,
crazy powerful bond with
water and release a doo-doo load
of energy and that energy
can be used to do work.
The single phosphate
forming a bond with water
is actually where all the
energy in ATP comes from,
when ATP breaks
off that terminal
phosphate and becomes ADP.
This is important.
We want to build ATP.
In order to do that,
we have to have ADP and P,
and we have to like rip the
phosphate off of
the water molecule,
you basically are water,
and combine it with ADP.
And like where are we going to
get the energy to
make this happen?
How are we going to
do this because
it's going to require energy?
Where are we going to get
the energy to make it happen?
I'm not going to tell you.
You have the next lecture to
find out the answer to that.
But you know, just looking at
the chemical equation for
what are we even talking about,
cellular respiration,
you can totally figure out
where the energy comes from.
I'll be right back.
