Hi. It's Mr. Andersen and in this video I'm going to talk about adenosine
triphosphate. Otherwise known as ATP. ATP is usually shown with this yellow starburst
behind it. And that's because it contains energy. In fact it's the energy coinage of
all life on our planet. And most of you probably know that but you might not know the structure
of ATP. And so let's begin with the adenine. Adenine is a purine and it's a nitrogenous
base. That means that the black in going to be carbon but the blue is going to be nitrogen.
Where have we seen nitrogenous bases? Remember that's going to be the rungs found on the
inside of DNA. We also have a ribose sugar. And then we're going to have not one phosphate
group. Phosphate is phosphorus surrounded by oxygen. But we're going to have three phosphate
groups. And so let's start with the adenine and the ribose. They're attached together
and they form a chemical called adenosine. If we add a phosphate to that, we have AMP
or adenosine monophosphate. If we were to add another phosphate to that we've now got
adenosine diphosphate or ADP. But if we add that third phosphate we now have ATP, or adenosine
triphosphate. Now these last phosphates are important. In fact I like to think of the
bond between these last two phosphates like a spring. As we attach that last phosphate
on, we're storing energy. And so there's potential energy in that bond. There's also going to
be potential energy in this bond right here as well. And so when we release that phosphate,
we can release a little bit of energy. And so let's look at that. And so what is ATP?
Here it is again? So we've got our adenine, our ribose sugar. And then we have our three
phosphates. But you can think of it like a recharged battery. It's a battery that's charged
up. It has a certain amount of potential energy. In fact if we were to take ATP, which would
just look like salt if you were to have it in a solid form, and we were to add it to
water, it would all hydrolyze. In other words it would all breakdown into ADP. And so let's
look at what's going on here. So if this is water, that water will break this last phosphate
group. In other words we're going to add an OH on one side and H on the other side. Remember
we call that hydrolysis or breaking with water. And we create ADP. Now we have just two phosphates
here. Well what happens to that third phosphate? It's released. And so lots of times when you're
dealing with ATP you're going to see this P with a subscript of i. What does that stand
for? That's this phosphate group that's been given off. And since there is a certain amount
of potential energy in this bond, when it's released that phosphate has a certain amount
of potential energy as well. So in other words, if we were to let ATP just sit in water, it
would all eventually hydrolyze and it would all become ADP and we'd have these loose phosphates.
That's going to be like a battery that's lost its charge. And so what do we do in life?
Well in life we're going to tap some energy. And so we could do that in respiration by
breaking down glucose. Or in photosynthesis by taking in energy from the sun. And we're
going to attach that phosphate group again. And that's called a dehydration reaction.
And so when we attach the phosphate we now make ATP. When we break it then we're going
to release energy. And so let's start by talking about the building. And so when do we produce
ATP? We're going to do that in cellular respiration. And so remember on the inside of that mitochondria
we have these proteins called ATP synthase. And what happens in all of respiration is
we build up a gradient of protons on the outside of that. And as they flow in, we make ATP.
Now it's worth pausing for just a moment and talking about, you know, how does ATP know
where to go. And how does ADP know where to go? Well if you're to think about it, let's
look right here. As we're converting ADP and a phosphate back into ATP, they're disappearing.
So you can think of in the mitochondria that's going to be the lowest amount of ADP and phosphate
is going to be found right here. Why is that? It's because they're going to be converted
into ATP. Well where's the ATP going to flow from there? Well diffusion is going to move
it from an area of high concentration to low. And so it's going to move wherever it's used.
Once it's used, it converts back to ADP and a phosphate. And that's going to come right
back here to the inside of the mitochondria. Now remember plants are also going to produce
ATP. They're going to do it on the thylakoid membrane which is going to be this membrane
right here on the inside of the chloroplast. What are they using to make ATP? They're using
light, energy of light to do that. How is this different than the mitochondria? Remember
the phosphates or excuse me, the hydrogen protons are going to be on the inside of the
thylakoid membrane. As they flow out that's going to make ATP. What do we use that for
in plants? Remember out here in the Calvin Cycle we're going to use that to make sugars.
Now plants also have mitochondria so they can break down that sugar and make ATP. And
so that's how we're producing it. What does it do though? Once we release that phosphate,
what is it used for? Well let me give you three good ways that it's used. So if we release
that phosphate it can be used in active transport. And so this right here is the sodium potassium
pump. This is going to be found on most of the cells in your body. But it's especially
important in the neurons of your body because you maintain this gradient and that's how
nerves actually work or impulses work. And so let's watch what's going on. We have ATP
right here. It's going to give up that phosphate. And that phosphate is going to bind to this
sodium potassium pump. As it does that, it's going to use the energy of that phosphate
to pump three sodium ions out. We're then going to have two potassium ions that will
bind to the inside of that pump and that's going to flow to the inside as we release
that phosphate. So again, what are we using? We're using active transport to pump sodium
out and potassium in. How much of your energy right now is going to that? About 20% of the
energy in your body right now is going to ATP which is running the sodium potassium
pump and keeping all of those neurons working. So it's really important. How else do we use
ATP? Well when we release that phosphate our muscles move using ATP. And so what's going
to happen is the phosphate will bind to this myosin The myosin is going to be a protein
and it will attract that to an actin and it's going to cause your muscle to contract. And
so your muscles contract using this phosphate that is released from ADP. What do we have
to do with that phosphate in ADP? Again, we have to regenerate ATP so that we can do this
again. Where else do we have this? Well in the formation of polymers. And so when we're
building polymers the easiest way to do that is to add a phosphate. And so let me kind
of show you where we're at. This is tRNA. Remember tRNA is going to transfer the amino
acid to the ribosome. And it's going to build proteins. And so how does that work? First
thing is we're going to have ATP and that's going to bind to the enzyme. And then it's
going to allow us to attach that amino acid on to the tRNA. And so we can build big polymers
like that. In fact, RNA is built using ATP. What does that mean? Well let's go to it.
ATP is old school. What does that mean? It's been around from the beginning of time. It
was used by LUCA. LUCA remember is the Last Universal Common Ancestor. In other words
that is the ancestor of all cells on our planet. And so this is a phylogenetic tree of all
life on our planet. We would have us, eukaryotes over here. We have archaea. And then all of
this is bacteria. But scientists believe that that first ancestor of all life had a few
properties. Number one they used ATP. They had RNA and DNA. They had the ability to use
glucose. They used proteins, ribosomes, membranes and ion channels. And so let's say that LUCA
kind of looked like this. It's a simplified cell. Well how did scientists come up with
this? Why is it that this cell had to have all of those things? Well that's because those
things are found in all cells on our planet. Not only us, but it's going to be found in
prokaryotic cells and archaea. So we know that that first organism had that and used
ATP for its energy. And that's because it's found in all cells. And so ATP has been there
from the beginning. But let's look at how prevalent ATP is in these other molecules.
And so let's look at RNA. So what's RNA. Remember it's going to be kind of the worker of DNA.
But let's look right here into one of these nucleotides inside RNA. What do we find? Well
we find adenine. We find a ribose sugar. And then we have a phosphate. Well what does that
look like? That looks like ATP. Except only one phosphate instead of two. And so when
I said we're building RNA, we really are building that using ATP. And you can see how cool that
is. That the ATP, the energy that we use or the molecule that we use for energy was also
a part of that first genetic code. And so it was kind os co-opted for two uses. Let's
look at DNA. DNA also has this adenine. It has a deoxy sugar. And there's an enzyme that's
actually going to switch that. But it's also really close in structure to ATP. All cells
use glucose. What do we use glucose to do? Remember we're going to breakdown glucose
in the mitochondria. And we're going to make ATP. All life is built of proteins and ribosomes
do that. Well, how do we do that? Remember it's going to be ATP that's binding those
amino acids on to the tRNA so that we can build them inside the ribosome. And remember
all cells are also going to have membranes and use ion channels. Well if you look at
it, that ion channel like that sodium potassium pump uses ATP. And if you were to look even
in the phospholipids that make up the membrane, what do we find right here in the middle?
We find that phosphate group. And so ATP has been around forever. It's used by all of life.
It's pretty simple. Just add a little bit of energy to ADP and you've got ATP. If you
release that energy, give off a phosphate you can do work. So that's ATP. And I hope
that was helpful.