NOTES – Cell Energy Part NOTES – Cell Energy Part 11

Adenosine Triphosphate (ATP)Adenosine Triphosphate (ATP)

Why do cells need Why do cells need energy?energy?

In what ways are our cells like a In what ways are our cells like a tower?tower?

Are they Are they organizedorganized? Do they have ? Do they have structure?structure?

There there forces in the environment There there forces in the environment that act to destroy the cell’s structurethat act to destroy the cell’s structure Randomly moving moleculesRandomly moving molecules Physical forcesPhysical forces Chemical attackChemical attack

Disorder (entropy) is always on the Disorder (entropy) is always on the increaseincrease

How can cells maintain their highly How can cells maintain their highly ordered structure?ordered structure?

It takes It takes energyenergy, work, and , work, and information to maintain orderinformation to maintain order

Cells need energy just to stay the Cells need energy just to stay the way they are and not break downway they are and not break down

What do cells use energy What do cells use energy for?for?

Repair themselvesRepair themselves GrowthGrowth ReproductionReproduction MovementMovement Active transportActive transport Protein synthesisProtein synthesis

ATP – The “energy currency” of ATP – The “energy currency” of the cellthe cell

ATP molecules are the basic energy ATP molecules are the basic energy source for cellssource for cells

ATP stands for ATP stands for aadenosine denosine ttriripphosphatehosphate ATP molecules carry just enough energy ATP molecules carry just enough energy

to power a variety of cell activitiesto power a variety of cell activities

Structure of ATPStructure of ATP ATP molecules have three parts:ATP molecules have three parts:

1.1. Adenine (a nitrogen-containing compound)Adenine (a nitrogen-containing compound)

2.2. Ribose (a 5-carbon sugar)Ribose (a 5-carbon sugar)

3.3. 3 Phosphate Groups3 Phosphate Groups

ATP MoleculeATP Molecule

How does ATP store How does ATP store energy?energy?

Chemical energy is Chemical energy is stored in the bond stored in the bond between an ATP between an ATP molecule’s second and molecule’s second and third phosphate groupthird phosphate group

Breaking the bond Breaking the bond releases energy for releases energy for cellular workcellular work

ATP becomes ADP ATP becomes ADP (adenosine (adenosine diphosphate)diphosphate)

The ATP CycleThe ATP Cycle

1.1. Energy is used to Energy is used to bond ADP to a free bond ADP to a free phosphate creating phosphate creating a high-energy ATP a high-energy ATP moleculemolecule

2.2. ATP is broken ATP is broken down into ADP, down into ADP, releasing stored releasing stored energy for cell energy for cell workwork

The ATP Cycle ContinuedThe ATP Cycle Continued

ATP is a high-ATP is a high-energy moleculeenergy molecule

ADP is a low-energy ADP is a low-energy moleculemolecule

When ATP is broken When ATP is broken down, ADP and the down, ADP and the extra phosphate extra phosphate can be recycled can be recycled into more ATPinto more ATP

ATP Cycle EquationsATP Cycle Equations

Cell storing energy (endergonic):Cell storing energy (endergonic): ADP + P + energy ADP + P + energy ATP ATP

Cell releasing energy (exergonic):Cell releasing energy (exergonic): ATP ATP ADP + P + energy ADP + P + energy

ATP is like a rechargeable ATP is like a rechargeable batterybattery

Batteries are used, giving Batteries are used, giving up their energy and can up their energy and can only be reused after the only be reused after the input of new energyinput of new energy

ATP is the recharged ATP is the recharged battery while ADP is the battery while ADP is the used batteryused battery

When the third When the third phosphate is cut loose, phosphate is cut loose, ATP becomes ADP, and ATP becomes ADP, and the stored energy is the stored energy is released.released.

The input of additional The input of additional energy (plus a phosphate energy (plus a phosphate group) "recharges" ADP group) "recharges" ADP into ATPinto ATP

How fast is the ATP cycle?How fast is the ATP cycle?

A working muscle cell recycles all of its A working muscle cell recycles all of its ATP about once each minuteATP about once each minute

That’s about 10 million molecules of ATP That’s about 10 million molecules of ATP consumed & regenerated per second, per consumed & regenerated per second, per cell! (600 million molecules per minute!)cell! (600 million molecules per minute!)

If ATP was not continuously regenerated, If ATP was not continuously regenerated, you would need to consume an amount you would need to consume an amount roughly equal to your bodyweight every roughly equal to your bodyweight every day to meet the energy needs of your day to meet the energy needs of your cells!cells!

How do cells make ATP?How do cells make ATP? There are a variety of processes that There are a variety of processes that

different types of cells use to produce ATPdifferent types of cells use to produce ATP Eukaryotic cells produce ATP during 2 Eukaryotic cells produce ATP during 2

main processes:main processes:

1.1. PhotosynthesisPhotosynthesis (plant cells only) – ATP (plant cells only) – ATP is made using energy from the sun, then is made using energy from the sun, then immediately used to help chloroplasts immediately used to help chloroplasts make larger food moleculesmake larger food molecules

2.2. RespirationRespiration (plant and animal cells) – (plant and animal cells) – ATP is made using energy from food ATP is made using energy from food moleculesmolecules

Cells use ATP molecules for Cells use ATP molecules for their energy needstheir energy needs

As ATP is used up, more is As ATP is used up, more is made by the cellmade by the cell

Cells need a continuous input Cells need a continuous input of energy in order to keep of energy in order to keep making ATPmaking ATP