Making energy ATP The point is to make

Making energy! ATP The point is to make ATP! AP Biology 2008 -2009

AP Biology

Chemical energy First Law Of Thermodynamics (a) First law of thermodynamics: Energy can be transferred or transformed but Neither created nor destroyed. For example, the chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movement in (b). Figure 8. 3 AP Biology

Heat Second Law co 2 + H 2 O (b) Figure 8. 3 AP Biology Second law of thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism.

AP Biology

Free Energy AP Biology

Reactions in a Closed System: ∆G < 0 ∆G = 0 What would happen To a living System if it were closed? AP Biology

Body Cells: ∆G < 0 What do we Need to Stay alive? AP Biology

The energy needs of life § Organisms are endergonic systems u What do we need energy for? § synthesis w building biomolecules § reproduction § movement § active transport § temperature regulation AP Biology

Where do we get the energy from? § Work of life is done by energy coupling u use exergonic (catabolic) reactions to fuel endergonic (anabolic) reactions digestion + synthesis + AP Biology + energy

Living economy § Fueling the body’s economy u eat high energy organic molecules § food = carbohydrates, lipids, proteins, nucleic acids u break them down § digest = catabolism u capture released energy in a form the cell can use § Need an energy currency u u AP Biology a way to pass energy around need a short term energy storage molecule Whoa! Hot stuff! ATP

ATP § Adenosine Tri. Phosphate u modified nucleotide § nucleotide = adenine + ribose + Pi AMP § AMP + Pi ADP § ADP + Pi ATP u adding phosphates is endergonic How efficient! Build once, use many ways AP Biology high energy bonds

How does ATP store energy? AMP ADP ATP I think he’s a bit unstable… don’t you? O– O– O– –O P –O O––P OO P––O O– P O– O O O § Each negative PO 4 more difficult to add u a lot of stored energy in each bond § most energy stored in 3 rd Pi § 3 rd Pi is hardest group to keep bonded to molecule § Bonding of negative Pi groups is unstable u u spring-loaded Pi groups “pop” off easily & release energy AP Biology Instability of its P bonds makes ATP an excellent energy donor

How does ATP transfer energy? ADP ATP O– O– O– –O P –O O– P O– O O– –O P O – + O 7. 3 energy § ATP ADP u releases energy § ∆G = -7. 3 kcal/mole § Fuel other reactions § Phosphorylation u released Pi can transfer to other molecules § destabilizing the other molecules AP Biologyu enzyme that phosphorylates = “kinase”

An example of Phosphorylation… § Building polymers from monomers need to destabilize the monomers u phosphorylate! u H C OH H + H C HO + ATP simple! H AP Biology +4. 2 kcal/mol “kinase” C It’s never that OH C synthesis + P enzyme -7. 3 kcal/mol + C C O C P H H H C HO C C O -3. 1 kcal/mol enzyme H H H C C OHHO + H 2 O ADP + Pi

Another example of Phosphorylation… § The first steps of cellular respiration u beginning the breakdown of glucose to make ATP Those phosphates sure make it uncomfortable around here! glucose C-C-C-C hexokinase phosphofructokinase P 2 ATP C C 2 ADP C fructose-1, 6 b. P P-C-C-C-P AP Biology DHAP P-C-C-C G 3 P C-C-C-P H P activation energy

ATP / ADP cycle Can’t store ATP cellular § good energy donor, not good energy storage respiration ü too reactive ü transfers Pi too easily ü only short term energy storage § carbohydrates & fats are long term energy storage Whoa! Pass me the glucose (and O 2)! AP Biology ATP 7. 3 kcal/mole ADP + Pi A working muscle recycles over 10 million ATPs per second

Cells spend a lot of time making ATP! The point is to make ATP! What’s the point? AP Biology

How is ATP Made in a Cell? Substrate Level Phosphorylation AP Biology

Chemiosmosis Start with a mitochondrion or chloroplast Trap H+ in the intermembrane space AP Biology

Chemiosmosis Start with a mitochondrion or chloroplast Trap H+ in the intermembrane space How can this lead to ATP production? AP Biology

H+ ATP synthase H+ § Enzyme channel in H+ H+ H+ rotor mitochondrial membrane u u permeable to H+ H+ flow down concentration gradient § flow like water over water wheel § flowing H+ cause change in shape of ATP synthase enzyme § powers bonding of Pi to ADP: rod catalytic head ADP + P ATP ADP + Pi ATP AP Biology But… How is the proton (H+) gradient formed? H+

That’s the rest of my story! Any Questions? AP Biology 2008 -2009