Carbon Cycles Through Organisms autotrophes heterotrophes

All Cells Respire Plants don’t do photosynthesis FOR animals They metabolize the sugars themselves!

Respiration Transforms Energy Anaerobically (without O2): 4 ATP Aerobically: 38 ATP It’s catabolic! Its exergonic! It’s redox! It’s enzyme-facilitated!

Recall: Catabolic & Exergonic - breaking down & releasing energy Redox - transferring e- Enzyme facilitated glucose oxygen releasing nrg forming water

Fuel the Body to fuel the cells 1. Consume organic molecules carbohydrates, lipids, proteins 2. Digest them, releasing energy • catabolic rxn 3. Cells transform released energy into a useable form; an energy currency • a vehicle to pass energy around • a short term energy storage molecule ATP

ATP - Adenosine TriPhosphate • A modified nucleotide adenine + ribose + PO4-  AMP AMP + PO4-  ADP ADP + PO4-  ATP • adding the P is key! phosphorylation 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? During oxidative phosphorylation, electrons are transferred from electron donors to electron acceptors such as oxygen, in redox reactions. These redox reactions release energy, which is used to form ATP.

ATP stores energy P O– O –O P O– O –O P O– O –O P O– O –O P O– O –O AMP ADP ATP ~ Each PO4- more difficult to add negative to negative a lot of stored energy in each bond (most in the third) 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 ~ Final P group pops off easily & transfers energy • bonding of P groups is unstable • instability makes ATP a great energy donor

Phosphorylation Transfers Energy 7.3 kcal P O– O –O P O– O –O P O– O –O + ATP ADP ATP  ADP : Releases energy Use to fuel other reactions : Phosphorylation released PO4- transferred to another molecule destabilizes the other molecule by stealing e- phosphorylation facilitated by enzyme kinase 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.

ATP / ADP are cycled ATP is unstable ATP ~ good energy donor ~ poor energy storage too reactive; transfers P easily ~ a renewable resource ADP P + A working muscle recycles over 10 million ATPs per second

Phosphorylation Occurs in Glycolysis Phosphate transfer activates the breakdown of glucose glucose C-C-C-C-C-C C H P ATP 2 hexokinase ADP 2 phosphofructokinase These are the very first steps in respiration — making ATP from glucose. Fructose-1,6-bisphosphate (F1,6bP) Dihydroxyacetone phosphate (DHAP) Glyceraldehyde-3-phosphate (G3P) 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. P-C-C-C-C-C-C-P P-C-C-C C-C-C-P PGAL - Phosphoglyceraldehyde….. becoming Pyruvate

Glycolysis ‘sugar’ + ‘break apart’ Occurs in cytoplasm (cytosol) of all organisms 10 step biochemical pathway Enzyme - facilitated 2 ATP Reactant: 6 C glucose + 2 ATP Product: two 3C pyruvate +4 ATP + 2 NADH e- e- NADH NADH?

Again, NADH?? 4 ATP Start here Got fructose? Enter pathway here Invest 2 ATP phosphorylate PGAL e- e- 4 ATP 2 NADH Again, NADH??

Electron Transfer Molecules *NAD+ coenzymes NADH ^FAD cofactors FADH2 oxidizing reducing donates e- accepts e- *Nicotinamide adenine dinucleotide ^Flavin adenine dinucleotide

Pyruvate options Anaerobic options All Organisms plants & animals yeast bacteria muscle cells

Anaerobic Resp v1 : alcoholic fermentation 3 C Pyruvate acetlyaldehyde + CO2 2 C ethanol 3C Pyruvate becomes 2 C acetylalcohol, which accepts the H from NADH producing NAD and ethanol

Anaerobic Resp v1 : alcoholic fermentation Ethanol is toxic to yeast at about 12% limiting the alcohol content of naturally fermented products some bacteria & yeast Grain alcohol is pulled off the mash, collected therefore concentrated. “The grain alcohol will vaporize at 173º F and enter the arm. Collect this liquid in a glass jar”

Fermentation v2: Lactate 3 C Pyruvate 3 C lactate (lactic acid) (No CO2)

Fermentation v2: Lactate whales, porpoises, and seals are able to concentrate their blood in the center of their bodies, and therefore their heart rates can be slower and their hearts do not have to work as hard. They have more of a special oxygen-storage molecule called myoglobin in their muscles, enabling them to store a lot of O2 before a dive. While submerged, diving animals use lactic acid fermentation to harvest the energy needed to swim, and then once they surface and breathe in O2, they are able to re-convert the lactic acid that has built up in their muscles back into pyruvic acid, which is then sent through the rest of the cellular respiration process to harvest more energy and form more ATP.