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

2. 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).

3. 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?

4. 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

5. 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

6. 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

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

8. 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

9. 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

10. 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

11. 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

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

13. 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

14. 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

15. 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

16. 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

17. The ATP cycle
Energy Stored
ADP
ATP
Energy Released

18. 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

19. The NADP cycle
Energy Stored
NAD+
NADP
Energy Released