ATP: Adenosine triphosphate | Energy and enzymes | Biology | Khan Academy

Summary

In this video, Sal explains why ATP, or adenosine triphosphate, is considered the energy currency of biological systems. He breaks down the molecular structure of ATP, highlighting the adenosine and three phosphate groups. Sal illustrates how ATP stores energy in its high-energy bonds, which, when broken through hydrolysis, release energy that cells use for various biological processes. He also contrasts ATP with ADP (adenosine diphosphate) and discusses how energy is both stored and released during ATP-ADP conversion, emphasizing ATP's critical role in processes like photosynthesis and cellular function.

Takeaways

• 🔋 ATP (Adenosine Triphosphate) is referred to as the 'currency of energy' in biological systems.
• 🧬 ATP consists of two main parts: adenosine (adenine + ribose) and three phosphoryl groups (triphosphate).
• ⚡ The bonds between the phosphoryl groups are high-energy bonds, meaning the electrons are in a high-energy state.
• 💥 When one of these bonds is broken, energy is released as the electrons move to a lower energy state.
• 🌊 Hydrolysis occurs when ATP is in the presence of water, resulting in the release of one phosphate group and forming ADP (Adenosine Diphosphate).
• 🔄 The conversion from ATP to ADP releases energy that can be used for various biological processes.
• 🌱 In processes like photosynthesis, light energy is used to reattach the phosphate group to ADP, forming ATP and storing energy.
• 🔥 The energy released from ATP hydrolysis can be used to generate heat or power other biological reactions.
• 🔗 ATP is essential for biological systems to function, enabling the storage and release of energy as needed.
• 🔧 Energy from ATP can change the shape of proteins or drive other reactions in the body.

Q & A

What is ATP and why is it referred to as the 'currency of energy'?

ATP, or adenosine triphosphate, is a molecule that stores and transfers energy within biological systems. It's referred to as the 'currency of energy' because it provides energy for various cellular processes by releasing energy when one of its high-energy phosphate bonds is broken.

What are the main components of ATP?

ATP consists of an adenosine molecule, which is made of adenine and ribose, and three phosphoryl groups. These components are critical for its function as an energy carrier.

How does ATP store energy?

ATP stores energy in the bonds between its phosphate groups, particularly the bonds between the second and third phosphate. These are high-energy bonds, meaning that when they are broken, energy is released.

What happens during the hydrolysis of ATP?

During ATP hydrolysis, one of the phosphate groups is removed, turning ATP into ADP (adenosine diphosphate). This process releases energy because the electrons move from a high-energy state to a more stable, lower-energy state.

What is the difference between ATP and ADP?

ATP (adenosine triphosphate) contains three phosphate groups, while ADP (adenosine diphosphate) contains two phosphate groups. ATP stores more energy, which is released when it is converted to ADP.

What role do the high-energy bonds in ATP play?

The high-energy bonds in ATP store energy that can be released when the bond is broken, allowing the energy to be used for various cellular processes such as muscle contraction, protein synthesis, and cell signaling.

What analogy is used to explain the concept of high-energy states in the script?

The analogy of being in a plane at a high altitude is used. Just as a person jumping out of a plane releases energy as they fall to a lower altitude, the electrons in ATP bonds release energy as they move to a lower, more stable state.

How is ATP involved in processes like photosynthesis?

In processes like photosynthesis, energy from light is used to add a phosphate group to ADP, converting it into ATP. This stores energy that can later be used by the cell.

What happens to the energy released from ATP hydrolysis?

The energy released from ATP hydrolysis can be used in multiple ways, such as generating heat or driving other biochemical reactions. It can also change the shape of proteins or power cellular movements.

Why is ATP regeneration important for cellular functions?

ATP regeneration is essential because cells constantly need energy for various functions. Processes like photosynthesis or cellular respiration replenish ATP by adding a phosphate group back to ADP, ensuring a continuous supply of energy for the cell.

Outlines

00:00

🔬 ATP: The Energy Currency

The paragraph introduces ATP (adenosine triphosphate) as the energy currency in biological systems. It explains the complexity of ATP's molecular structure and aims to simplify understanding by breaking it down into its components: adenosine and the three phosphoryl groups. The adenosine part consists of adenine connected to a ribose, while the triphosphate part consists of three phosphoryl groups. The concept of high-energy bonds is introduced, explaining that these bonds hold energy that can be released when they break, similar to potential energy being released when an object falls. The paragraph uses the analogy of a person jumping from a plane to a couch to illustrate the release of energy from a high to a low energy state. It also discusses the hydrolysis process where ATP can lose a phosphoryl group to become ADP (adenosine diphosphate), releasing energy in the process.

05:01

🌱 Energy Conversion in Biochemical Reactions

This paragraph continues the discussion on ATP by focusing on the energy conversion that occurs during biochemical reactions. It describes how energy is released when ATP is converted to ADP through hydrolysis, and conversely, how energy is stored when ADP is converted back to ATP. The paragraph mentions that this energy conversion is a common theme in biochemistry, with examples such as photosynthesis, where light energy is used to add a phosphate group back to ADP to form ATP. It also touches on how the released energy from ATP can be used for various purposes in biological systems, such as generating heat or facilitating other reactions by changing the conformation of proteins.

Keywords

💡ATP (Adenosine Triphosphate)

ATP, or Adenosine Triphosphate, is often referred to as the energy currency of cells. It stores and releases energy needed for various biological processes. In the video, ATP is described as a molecule composed of adenosine and three phosphoryl groups, and it plays a critical role in energy transfer in biological systems.

💡Adenosine

Adenosine is a combination of adenine (a nitrogenous base) and ribose (a sugar). It forms the structural base of ATP. The video explains that adenosine is the portion of ATP that is attached to the triphosphates, which are responsible for the energy storage function of the molecule.

💡Triphosphates

Triphosphates are three phosphoryl groups attached to the adenosine part of ATP. The energy stored in the bonds between these groups is released when the bonds are broken. The video emphasizes that these bonds are considered 'high energy,' meaning they can release significant energy when broken.

💡High Energy Bonds

High energy bonds in ATP refer to the bonds between the phosphate groups. When these bonds break, they release energy because the electrons move to a lower energy state. The video compares this process to the release of potential energy when an object falls.

💡Hydrolysis

Hydrolysis is the process in which water is used to break a bond, in this case, between phosphate groups in ATP. The video describes how ATP undergoes hydrolysis to lose one phosphate group and become ADP (Adenosine Diphosphate), releasing energy in the process.

💡ADP (Adenosine Diphosphate)

ADP is a molecule formed when ATP loses one of its phosphate groups during hydrolysis. It contains two phosphoryl groups instead of three. In the video, ADP is described as a lower-energy form of ATP, which can later be converted back into ATP when energy is stored.

💡Energy Release

Energy release occurs when the high-energy bonds in ATP are broken, particularly during the conversion of ATP to ADP. The video explains that this energy is used for various biological processes, such as powering chemical reactions or generating heat.

💡Energy Storage

Energy storage in biological systems involves the conversion of ADP back to ATP by adding a phosphate group. The video discusses how this process requires energy, such as from photosynthesis or cellular respiration, to store energy in ATP for future use.

💡Phosphate Group

Phosphate groups are the components of ATP that store energy. Each group consists of a phosphorus atom surrounded by oxygen atoms. The video shows how the breaking of these groups from ATP releases energy, while adding them to ADP stores energy.

💡Photosynthesis

Photosynthesis is a process in which light energy is used by plants to produce ATP from ADP. The video mentions photosynthesis as an example of how energy is stored in ATP, highlighting its importance in converting light energy into chemical energy stored in ATP.

Highlights

ATP, or adenosine triphosphate, is often referred to as the energy currency of biological systems.

Adenosine triphosphate consists of adenosine and three phosphoryl groups, forming a complex molecular structure.

The adenosine part of ATP is composed of adenine connected to a ribose sugar.

The three phosphoryl groups are the key to ATP's role in energy storage, as they form high-energy bonds.

These high-energy bonds store electrons in a higher energy state, and breaking these bonds releases energy.

The concept of 'high-energy bonds' means that breaking the bond allows electrons to move to a more stable, lower energy state, releasing energy.

An analogy for the energy release in ATP is a person jumping from a plane — from a high-energy state to a lower one, releasing energy during the transition.

Hydrolysis of ATP occurs when it reacts with water, breaking off one phosphate group and forming ADP (adenosine diphosphate).

The hydrolysis reaction of ATP to ADP releases energy, which is utilized by biological systems.

ATP stores energy in its bonds, and hydrolysis releases this stored energy for biological functions.

In biological systems, energy is used to convert ADP and phosphate back into ATP, storing energy again.

Photosynthesis is one process where light energy is used to convert ADP into ATP by adding a phosphate group.

The energy released from ATP hydrolysis can be used to generate heat or drive other chemical reactions.

The energy from ATP can change the conformation of proteins, which is critical for many cellular processes.

ATP is central to cellular energy management, being used and regenerated in cycles to fuel biological reactions.

Transcripts

Sal: ATP or adenosine triposphate is often referred to as

the currency of energy, or the energy store, adenosine,

the energy store in biological systems.

What I want to do in this video is get

a better appreciation of why that is.

Adenosine triposphate.

At first this seems like a fairly complicated term,

adenosine triphosphate, and even when we look at its

molecular structure it seems quite involved, but if we break

it down into its constituent parts it becomes a little bit

more understandable and we'll begin to appreciate why,

how it is a store of energy in biological systems.

The first part is to break down this molecule between

the part that is adenosine and the part that

is the triphosphates, or the three phosphoryl groups.

The adenosine is this part of the molecule,

let me do it in that same color.

This part right over here is adenosine,

and it's an adenine connected to a ribose

right over there, that's the adenosine part.

And then you have three phosphoryl groups,

and when they break off they can turn into a phosphate.

The triphosphate part you have, triphosphate,

you have one phosphoryl group, two phosphoryl groups,

two phosphoryl groups and three phosphoryl groups.

One way that you can conceptualize this molecule which will

make it a little bit easier to understand how it's a store

of energy in biological systems is to represent this whole

adenosine group, let's just represent that as an A.

Actually let's make that an Ad.

Then let's just show it bonded to

the three phosphoryl groups.

I'll make those with a P and a circle around it.

You can do it like that, or sometimes you'll see it

actually depicted, instead of just drawing these

straight horizontal lines you'll see it depicted

with essentially higher energy bonds.

You'll see something like that to show

that these bonds have a lot of energy.

But I'll just do it this way for the sake of this video.

These are high energy bonds.

What does that mean, what does that

mean that these are high energy bonds?

It means that the electrons in this bond are in a

high energy state, and if somehow this bond could be

broken these electrons are going to go into a more

comfortable state, into a lower energy state.

As they go from a higher energy state into a lower, more

comfortable energy state they are going to release energy.

One way to think about it is if I'm in a plane and

I'm about to jump out I'm at a high energy state,

I have a high potential energy.

I just have to do a little thing and I'm going

to fall through, I'm going to fall down,

and as I fall down I can release energy.

There will be friction with the air, or eventually

when I hit the ground that will release energy.

I can compress a spring or I can move a turbine,

or who knows what I can do.

But then when I'm sitting on my couch

I'm in a low energy, I'm comfortable.

It's not obvious how I could go to a lower energy state.

I guess I could fall asleep or something like that.

These metaphors break down at some point.

That's one way to think about what's going on here.

The electrons in this bond, if you can give them just

the right circumstances they can come out of that bond

and go into a lower energy state and release energy.

One way to think about it, you start

with ATP, adenosine triphosphate.

And one possibility, you put it in the presence of water and

then hydrolysis will take place, and what you're going to

end up with is one of these things are going to be essentially,

one of these phosphoryl groups are going to be

popped off and turn into a phosphate molecule.

You're going to have adenosine, since you don't

have three phosphoryl groups anymore, you're only

going to have two phosphoryl groups, you're going to

have adenosine diphosphate, often known as ADP.

Let me write this down.

This is ATP, this is ATP right over here.

And this right over here is ADP, di for two,

two phosphoryl groups, adenosine diphosphate.

Then this one got plucked off, this one gets plucked

off or it pops off and it's now bonded to the oxygen

and one of the hydrogens from the water molecule.

Then you can have another hydrogen proton.

The really important part of this I have not drawn yet,

the really important part of it,

as the electrons in this bond right over here go into

a lower energy state they are going to release energy.

So plus, plus energy.

Here, this side of the reaction,

energy released, energy released.

And this side of the interaction

you see energy, energy stored.

As you study biochemistry you will see time and time

again energy being used in order to go from ADP and

a phosphate to ATP, so that stores the energy.

You'll see that in things like photosynthesis

where you use light energy to essentially,

eventually get to a point where this P is put back on,

using energy putting this P back on to the ADP to get ATP.

Then you'll see when biological systems need to use energy

that they'll use the ATP and essentially hydrolysis

will take place and they'll release that energy.

Sometimes that energy could be used just to generate heat,

and sometimes it can be used to actually forward

some other reaction or change the confirmation of

a protein somehow, whatever might be the case.