Chapter 8.1 – 8.2 Energy and ATP! ATP

Energy needs of life  Organisms are endergonic systems  What do we need energy for?   synthesis (biomolecules)  reproduction  active transport  movement  temperature regulation

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

Chemical reactions of life  Metabolism  forming bonds between molecules  dehydration synthesis  anabolic reactions  breaking bonds between molecules  hydrolysis  catabolic reactions

Examples + +  dehydration synthesis H2OH2O H2OH2O  hydrolysis H2OH2O H2OH2O

Examples  dehydration synthesis  hydrolysis

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

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

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 + +

Living economy  Fueling the economy  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 Whoa! Hot stuff! ATP

 Adenosine Triphosphate  modified nucleotide  adenine + ribose + P i  AMP  AMP + P i  ADP  ADP + P i  ATP an RNA nucleotide How efficient! Build once, use many ways

Why does ATP store energy? P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O–O––O–O O  Each P i group more difficult to add  a lot of stored energy in each bond  most stored in 3rd P i  ∆G = -7.3 kcal/mole  Close packing of negative P i groups  spring-loaded The instability of its P bonds makes ATP an excellent energy donor I think he’s a bit unstable… don’t you?

How does ATP transfer energy? P O–O– O–O– O –O–O P O–O– O–O– O –O–O P O–O– O O–O––O–O energy P O–O– O–O– O –O–O +  Phosphorylation  when ATP does work, it transfers its 3rd P i to other molecules  ATP  ADP  releases energy  ∆G = -7.3 kcal/mole (-30kJ/mol)  it destabilizes the other molecule P O–O– O–O– O –O–O P O–O– O–O– O –O–O

An example of Phosphorylation…  Building polymers from monomers  need ATP for energy & to take the water out C H OH H OHOH C C H O H C + H2OH2O H2OH2O kcal/mol C H OH + C H P P + ATP ADP -7.3 kcal/mol H OHOH C C H O H C + + C H P P PiPi PiPi -3.1 kcal/mol “kinase” enzyme Kinases are enzymes involved with moving phosphate groups!

glucose C-C-C-C-C-C fructose-1,6-P P-C-C-C-C-C-C-P DHAP P-C-C-C PGAL C-C-C-P 2 ATP 2 ADP Another example of Phosphorylation…  The first steps of cellular respiration  beginning the breakdown of glucose  ATP enzyme 1 enzyme 3enzyme 4 enzyme 5 enzyme 6 enzyme 2 those phosphates sure make it uncomfortable around here

ATP / ADP cycle A working muscle recycles over 10 million ATPs per second Can’t store ATP for long periods  too reactive  transfers P i too easily  only short term energy storage  carbs & fats are long term energy storage

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

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