ATP Why do we use it for Energy?

ATP: Adenosine Triphosphate Consists of Adensosine + 3 Phosphates Consists of Adensosine + 3 Phosphates Highly unstable molecule Highly unstable molecule 3 phosphates each highly negative repel each other (like the wrong end of a magnet) 3 phosphates each highly negative repel each other (like the wrong end of a magnet) Hence a phosphate group is removed through hydrolysis energy is released (-7.3 kcal/mole) and breaks down into the more stable molecule ADP. Hence a phosphate group is removed through hydrolysis energy is released (-7.3 kcal/mole) and breaks down into the more stable molecule ADP.

ATP: Pictures Where does the Negativity come from? Oxygen Oxygen I think he’s a bit unstable… don’t you?

How 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 negative PO 4 more difficult to add Each negative PO 4 more difficult to add a lot of stored energy in each bond a lot of stored energy in each bond most energy stored in 3rd P i = releases energy ∆G = -7.3 kcal/mole 3rd P i is hardest group to keep bonded to molecule Bonding of negative P i groups is unstable Bonding of negative P i groups is unstable spring-loaded spring-loaded P i groups “pop” off easily & release energy P i groups “pop” off easily & release energy Instability of its P bonds makes ATP an excellent energy donor AMP ADPATP

Can’t store ATP  good energy donor, not good energy storage too reactive transfers P i too easily only short term energy storage  carbohydrates & fats are long term energy storage ATP / ADP cycle A working muscle recycles over 10 million ATPs per second Whoa! Pass me the glucose (and O 2 )! ATP ADP PiPi kcal/mole cellular respiration

Completely off Topic How can you remember what happens in Oxidation or Reduction? OIL RIG Oxidation is Loss of Electrons Reduction is Gain of Electrons PS. Making ATP is phosphorylation not Oxidation or reduction.

CELLULAR RESPIRATION C 6 H 12 O 6 + O 2 → CO 2 + H 2 O + energy

What questions should you be able to answer at the end of the unit? Why do you breath in oxygen? What do you breath out and why? How do mitochondria work? What is the difference between aerobic and anaerobic respiration? What are the steps of Glycolysis? What are the steps of Aerobic and Anaerobic Respiration?

CELLULAR RESPIRATION The complex process in which cells make ATP by breaking down organic compounds is known as cellular respiration.

NADH + 2H+ pyruvic acid

ANAEROBIC RESPIRATION When O 2 is absent, respiration is anaerobic and includes glycolysis and fermentation. When O 2 is absent, respiration is anaerobic and includes glycolysis and fermentation.

GLYCOLYSIS Glycolysis is a pathway in which one molecule of glucose is oxidized to produce two molecules of pyruvic acid. Takes place in the cytosol of the cell.

Glycolysis Continued The endproducts are 2 NADH, and 4 ATP First 3 steps of Glycolysis are endothermic, require energy in the form of 2 ATP. Subsequent steps are exothermic. What is the Net ATP produced by Glycolysis? Overview of Glycolysis

-2 ATP + 4 ATP 2 ATP per molecule of glucose.

What happens if you have too much ATP? Allosteric Inhibition PFK (Phosphofructokinase): Enzyme used in step 3 of glycolysis to create the 6 carbon sugar that breaks apart into P-C-C-C C-C-C-P Too much energy? ATP binds to the PFK halting the steps of gycolysis. Allosteric Enzyme

FERMENTATION When there is no oxygen available, the products of glycolysis enter fermentation where no further ATP is yielded however NAD is regenerated and is available for glycolysis again. When there is no oxygen available, the products of glycolysis enter fermentation where no further ATP is yielded however NAD is regenerated and is available for glycolysis again.

ENERGY YIELD

Who uses Anaerobic Respiration? You do with Aerobic Respiration Some bacteria survive on it (Botulinum & Tetnus) and can not survive in the presence of O 2. They are Obligate anaerobes. Facultative anaerobes can tolerate oxygen: Staph, E.Coli Facultative anaerobes can tolerate oxygen: Staph, E.Coli Anaerobic R. began Millions of years ago when earths atm. Had no O 2.

AEROBIC RESPIRATION If oxygen is available, pyruvic acid enters the pathways of aerobic respiration: the Krebs cycle and the electron transport chain.

OVERVIEW OF AEROBIC RESPIRATION In the Krebs cycle, the oxidation of glucose that began with glycolysis is completed and NAD is reduced to NADH. In the electron transport chain, NADH is used to make ATP. Prokaryotes: Cytosol Eukaryotes: Mitochondrial Matrix The Mitochondria At Work

When pyruvic acid reacts with a molecule called coenzyme A to form acetyl coenzyme A. Making Vinegar

The Krebs Cycle Cyclic process that produces the following products: CO 2, ATP, NADH + H +, and FADH 2. CO 2 is released. NADH + H +, and FADH 2 go to the electron transport chain. Krebs Cycle At the Bottom

ELECTRON TRANSPORT CHAIN In prokaryotes, the electron transport chain lines the cell membrane. ATP is produced by the electron transport chain when NADH and FADH 2 release hydrogen atoms, regenerating NAD and FAD. Electron Transport Chain E.T.C. revisited

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

Respiration. Virtual Respiration Lab