Why would ATP break off a phosphate to become ADP + P just to become ATP again? What is the purpose of converting ATP to ADP? Where does that P from ATP go to/do? I'm puzzled..
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Let's look at this as if the ATP were money you needed to spend. ATP molecules have the highest energy to spend in the cell, as if you had a $20 bill. When the cell needs energy for a metabolic process, it takes the energy from the wallet, or ATP molecules. Each time a phosphate is broken off, ATP loses some chemical energy which can be used by the cell.
In other words, you pay $10 for something with your origjnal $20 bill, and you now have $10 left from your original $20 bill. You still have money to spend, but less than what you started with because you've spent some of it already.
ADP (adenosine diphosphate) therefore has less energy (buying ability) than ATP (adenosine triphosphate) had. The ATP=your $20 bill. The ADP=your $10 bill. Not as much 'buying power' now, but it still has some.
Then, if the cell needs more energy, the ADP molecule "spends" its last phosphate, becoming AMP (adenosine monophosphate).
In money terms, you spend your $10 bill, and you'd have to go back to the bank to get more money because you're broke now. Well, AMP is 'broke' too..it has no more chemical energy to give to the cell, and it must return to the mitochondria (the "bank") where, in the Krebs cycle (cellular respiration), it gets recharged back to ADP and then ATP with the energy from the breakdown of glucose molecules.
In our analogy, you'd go to the bank and get another $20 bill, to 'recharge' your wallet so you can spend more money (energy).
Summary:
The bank=the mitochondria and the Krebs cycle performed there
Your $20=ATP molecule
Your $10=ADP molecule
Being broke=AMP molecule
Does this help?
In other words, you pay $10 for something with your origjnal $20 bill, and you now have $10 left from your original $20 bill. You still have money to spend, but less than what you started with because you've spent some of it already.
ADP (adenosine diphosphate) therefore has less energy (buying ability) than ATP (adenosine triphosphate) had. The ATP=your $20 bill. The ADP=your $10 bill. Not as much 'buying power' now, but it still has some.
Then, if the cell needs more energy, the ADP molecule "spends" its last phosphate, becoming AMP (adenosine monophosphate).
In money terms, you spend your $10 bill, and you'd have to go back to the bank to get more money because you're broke now. Well, AMP is 'broke' too..it has no more chemical energy to give to the cell, and it must return to the mitochondria (the "bank") where, in the Krebs cycle (cellular respiration), it gets recharged back to ADP and then ATP with the energy from the breakdown of glucose molecules.
In our analogy, you'd go to the bank and get another $20 bill, to 'recharge' your wallet so you can spend more money (energy).
Summary:
The bank=the mitochondria and the Krebs cycle performed there
Your $20=ATP molecule
Your $10=ADP molecule
Being broke=AMP molecule
Does this help?
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It is like a bus. It picks up people, transfers them to their stop, and then unpacks them so they can do their unsatisfying job that millions other could just as easily do. Then the bus goes back to get more people.
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My apologis. The Extra P simply hold the energy of ATP in it chemical binding. Upon breaking said bind, energy is released and used to as activation energy to power reactions. The P gets recycled into more ATP. The body tries its best to work in a cycle so that renewal is easier.
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My apologis. The Extra P simply hold the energy of ATP in it chemical binding. Upon breaking said bind, energy is released and used to as activation energy to power reactions. The P gets recycled into more ATP. The body tries its best to work in a cycle so that renewal is easier.