1. Chapter 8.1 – 8.2 Energy and ATP!

2. Jokes
Study biology they said
It will be fun they said

3. First Law of Thermodynamics
Energy can be neither created nor destroyed. It is just transferred and transformed.

4. Second Law of Thermodynamics
If energy cannot be created or destroyed, then why can’t organisms just recycle their energy after one meal?
During energy transfers/transformations, some energy is lost (usually as heat)
Every release of energy increases the entropy of the universe (as heat is released into the surroundings)

5. Second Law of Thermodynamics
As the cheetah runs, its body will break down macromolecules for energy. Much of the energy released is lost as heat.
HEAT
CO2 & H2O

6. Heat lost to the surroundings increases entropy of the surroundings

7. Organisms are open systems
Organisms absorb energy
Either as light energy or chemical energy from food
Release heat and metabolic waste products (CO2) to surroundings

8. Energy needs of life Organisms require constant energy input.
synthesis (biomolecules)
reproduction
active transport
movement
temperature regulation
Organisms require constant energy input.
What do we need energy for?
AP Link—Ch 06: Energy Concepts
Which is to say… if you don’t eat, you die… because you run out of energy.
The 2nd Law of Thermodynamics takes over!

9. Flow of energy through life
Life is built on chemical reactions
Can you please pass the salt?

10. Chemical reactions of life
Metabolism
forming bonds between molecules
dehydration synthesis
anabolic reactions
breaking bonds between molecules
hydrolysis
catabolic reactions

11. Examples
dehydration synthesis
H2O +
hydrolysis
H2O +

12. Examples
dehydration synthesis
hydrolysis

13. Chemical reactions & energy
Some chemical reactions release energy
exergonic
digesting polymers
hydrolysis = catabolism
Some chemical reactions require input of energy
endergonic
building polymers
dehydration synthesis = anabolism
digesting molecules = less organization = lower energy state
building molecules = more organization = higher energy state

14. Endergonic vs. Exergonic reactions
energy released
endergonic
energy invested
-G
G = change in free energy = ability to do work

15. Know how to calculate ΔG:
ΔG = ΔH - T ΔS
- ΔG = spontaneous
will occur on it’s own and release energy
+ ΔG = non-spontaneous
will occur if energy is put into it – will absorb energy

16. ΔG table: ΔH ΔS SPONTANEOUS? ENDERGONIC OR EXERGONIC Negative Positive
Yes
EXERGONIC (energy released) No
ENDERGONIC (energy absorbed)
low temperatures only
(at low temperatures only)
high temperatures only
(at high temperatures only)

17. Energy & life Organisms require energy to live
where does that energy come from?
often via COUPLING exergonic reactions (releasing energy) with endergonic reactions (needing energy)
energy + +
energy + +

18. ATP Living economy Fueling the economy Need an energy currency
eat high energy organic molecules (food)
break them down = catabolism (digest)
capture energy in form cell can use
Need an energy currency
a way to pass energy around
ATP
Whoa! Hot stuff!

19. Build once, use many ways
ATP
Adenosine Triphosphate
modified nucleotide
adenine + ribose + Pi  AMP
AMP + Pi  ADP
ADP + Pi  ATP
AP Link—Ch 06: ATP Molecule
Marvel at the efficiency of biological systems!
Build once = re-use over and over again.
Start with a nucleotide and add phosphates to it to make this high energy molecule that drives the work of life.
Let’s look at this molecule closer.
Think about putting that Pi on the adenosine-ribose ==>
EXERGONIC or ENDERGONIC?
an RNA nucleotide
How efficient!
Build once, use many ways

20. Why does ATP store energy?
I think he’s a bit unstable… don’t you? P O– O –O P O– O –O P O– O –O P O– O –O P O– O –O
Each Pi group more difficult to add
a lot of stored energy in each bond
most stored in 3rd Pi
∆G = -7.3 kcal/mole
Close packing of negative Pi groups
Not a happy molecule
Add 1st Pi  Kerplunk! Big negatively charged functional group
Add 2nd Pi  EASY or DIFFICULT to add? DIFFICULT takes energy to add = same charges repel  Is it STABLE or UNSTABLE? UNSTABLE = 2 negatively charged functional groups not strongly bonded to each other So if it releases Pi  releases ENERGY
Add 3rd Pi  MORE or LESS UNSTABLE? MORE = like an unstable currency • Hot stuff! • Doesn’t stick around • Can’t store it up • Dangerous to store = wants to give its Pi to anything
spring-loaded
The instability of its P bonds makes ATP an excellent energy donor

21. How does ATP transfer energy?+
Phosphorylation
when ATP does work, it transfers its 3rd Pi to other molecules
ATP  ADP
releases energy
∆G = -7.3 kcal/mole (-30kJ/mol)
it destabilizes the other molecule
How does ATP transfer energy?
By phosphorylating
Think of the 3rd Pi as the bad boyfriend ATP tries to dump off on someone else = phosphorylating
How does phosphorylating provide energy?
Pi is very electronegative. Got lots of OXYGEN!! OXYGEN is very electronegative. Steals e’s from other atoms in the molecule it is bonded to. As e’s fall to electronegative atom, they release energy.
Makes the other molecule “unhappy” = unstable. Starts looking for a better partner to bond to. Pi is again the bad boyfriend you want to dump.
You’ve got to find someone else to give him away to. You give him away and then bond with someone new that makes you happier (monomers get together).
Eventually the bad boyfriend gets dumped and goes off alone into the cytoplasm as a free agent = free Pi.

22. An example of Phosphorylation…
Building polymers from monomers
need ATP for energy & to take the water out C H OH O +
H2O
endergonic
“kinase” enzyme C H OH + P
ATP
ADP
exergonic
Monomers  polymers
Not that simple!
H2O doesn’t just come off on its own
You have to pull it off by phosphorylating monomers.
Polymerization reactions (dehydration synthesis) involve a phosphorylation step!
Where does the Pi come from? ATP H OH C O + P Pi
exergonic
Kinases are enzymes involved with moving phosphate groups!

23. Another example of Phosphorylation…
The first steps of cellular respiration
beginning the breakdown of glucose  ATP
glucose
C-C-C-C-C-C
those phosphates sure make it uncomfortable around here
2 ATP
2 ADP
enzyme 1
These are the very first steps in respiration — making ATP from glucose.
1st ATP used is like a match to light a fire…
initiation energy / activation energy.
The Pi makes destabilizes the glucose & gets it ready to split.
enzyme 2
fructose-1,6-P
P-C-C-C-C-C-C-P
enzyme 3
enzyme 4
enzyme 5
DHAP
P-C-C-C
PGAL
C-C-C-P
enzyme 6

24. ATP / ADP cycle Can’t store ATP for long periods too reactive
transfers Pi too easily
only short term energy storage
carbs & fats are long term energy storage
AP Movie—Ch 06: ATP/ADP cycle from (Biology Respiration Lecture)
A working muscle recycles over 10 million ATPs per second

25. Where is ATP needed? One example…
binding site
thin filament (actin)
myosin head
thick filament (myosin)
So that’s where those 10,000,000 ATPs
go!
Well, not all of it! 1 1
ATP
cross bridge 1 4 1 2
Cleaving ATP  ADP allows myosin head to bind to actin filament. 1 3

26. “The point is to make ATP!”
What’s the point?
“The point is to make ATP!”
Make ATP! That’s all I do all day... And no one even notices! I want a cookie!!!
Any Questions??