Energy and Life As you go thru the notes, answer the review questions that are on the next two slides

Review Questions What is the source of all of the energy that is found in living things? How do the following obtain food: autotrophs, heterotrophs, chemotrophs, decomposers? What are the two main energy compounds in living things (just use the initials).

4. How do the bonds between the phosphates in an ATP molecule compare in terms of energy available? 5. Explain how converting ADP to ATP stores energy. 6. Explain how converting ATP to ADP releases energy. 7. Why don’t living things try to get energy by converting ADP to AMP?

Where Does the Energy Come From? The energy that almost all living things use starts as solar energy Autotrophs (mainly plants) use the energy from the sun to make food chemicals that can be broken down to produce energy Heterotrophs will eat the autotrophs and use them as food chemicals that can be broken down to produce energy

Where Does the Energy Come From? Decomposers will use dead and decaying matter as food chemicals that can be broken down to produce energy Chemotrophs (certain bacteria) will turn chemicals from their environment directly into food chemicals that can be broken down to produce energy

The Energy Molecules of Living Things Adenosine TriPhosphate (ATP) is the primary energy compound Nicotinamide adenine dinucleotide phosphate (NADP) is the secondary energy compound Energy is stored or released by adding or removing phosphate (PO4-3) molecules from these molecules

These are all ways to represent a molecule of ATP A ― P ~ P ~ P

Notice that in all three models there are 3 molecules of phosphate ATP Notice that in all three models there are 3 molecules of phosphate A ― P ~ P ~ P

ATP Phosphate molecules have a negative charge so they naturally want to repel each other. It takes a lot of energy to hold the phosphate molecules close together. A ― P ~ P ~ P Regular chemical bond 10X high energy bond High energy bond

How ATP releases energy When a cell needs energy, it will use a water molecule as “scissors” to cut the last phosphate from the end of the ATP molecule. A ― P ~ P ~ P

How ATP releases energy The energy that was being used to hold the phosphate in place is now available for the cell to use. A ― P ~ P ~ Energy now available

How ATP releases energy When an ATP molecule loses a phosphate, it becomes ADP (adenosine diphosphate). A ― P ~ P

How ATP releases energy It is possible to take the phosphate off of an ADP molecule and turn it into AMP (adenosine monophosphate) but it rarely happens. A ― P

How ATP stores energy A ― P ~ P When a living things breaks down food molecules they provide the energy needed to “stick” the third phosphate to the end of the ADP molecule. A ― P ~ P

How ATP stores energy A ― P ~ P ~ P When a living things breaks down food molecules they provide the energy needed to “stick” the third phosphate to the end of the ADP molecule. A ― P ~ P ~ P Energy from food molecules New phosphate molecule

How ATP stores energy A ― P ~ P ~ P Other cell processes can also produce energy to build ATP molecules from ADP molecules A ― P ~ P ~ P Energy from food molecules New phosphate molecule

The ATP cycle Energy Stored ADP ATP Energy Released

NADP works in basically the same way The NADP cycle NADP works in basically the same way The NAD+ molecule will add a phosphate using the energy available when food molecules break down to make NADP The NADP molecule will release the phosphate molecule to make energy available to the cell

The NADP cycle Energy Stored NAD+ NADP Energy Released