ctober O 6 th , 2010
Ultimately what the cell uses is monosaccharide Fatty acids and phospholipids- make bilayer Can also store fatty acids and triglycerides as a sou Energy from glucose Can oxidize glucose with 6 O- make 6CO2 and 6 H2O Multistep pathway: Cell peels energy away in discrete cells To store energy in cofactors so it can use energy in other metabolic reactions rce of carbon and energy
Uncontrolled combustion: What if we burned it all at once? Raising 371 degrees at once is not helpful or safe for the body
Review of chemistry reactions H- free energy buried in a bond G: change in free energy Relating G to equilibrium Equation with RT Gi: free energy of given component Gi is the free energy of that component under standard conditions R is gas constant=8.315JK-1mol-1 The only thing that is not 1M in the body is water At equilibrium, there is no longer a change in free energy or to phrase it another way the free energies of the products and the reactatcs are equal so there is no dirivng force to push the reaction If G is negative- equilibrium towards products Interested in activity not concentration Glycolosis occurs in cytoplasm Reactions are coupled: how the cell gets energy out of the system and into the system
G does not equal G0 because RTlnK If we set G to 0, G0 is now equal to RTlnK Knowing K can get us G0 but then we need to know conditions in cell to get G Replacing K with concentrations [A][B]etc. helps us figure out G
Hexikinase (catalyst) approaches a globular molecule with a stereospecificity that lowers the activation energy Highly conserved pathway suggest that it was in use in an ancestor common to bacteria, archea and eukaryotes Coupled reactions ensure a G ATP ADP is extremely favorable Covalent bond cleavage of glucose to get 2 products: 1 product (?) used next in step. So as this product is depleted its favoring the left side of the reaction (using up the product for next step so pushes equilibrium to left) One class of high energy cofactors: ATP Another set high energy because they hold power for later Peeling energy of glucose in discrete steps Glycolytic book keeping Pyruvate can be burend aerobically or anerobically Cofactors ATP, NADH: high energy, used as currency for trading G Prosthetic groups: Heme in Hb (holo enzyme- has all components it needs) Free vs. bound in activity (concentration) Ca+2 very important signaling and a lot of it, free concentration is very low because it is bound by many different molecules Glycolosis: ADP, fair amount in cell, but mostly bound so free concentration is low Helps drive reaction from ATP ADP (think le chevalier)
ATP and Pi are essentially constant and ADP is low because most ADP is bound to protein Moreeee on this slide.. Anaerobic fate of pyruvate Mammals: fermentation lactate Aerobic fate of pyruvate Yeast fermentation EtOH and CO2 Consequences of eukaryotes having different compartments: shuttling pyruvate through membrane transporter (not lipid soluble) that gets it into the mitochondrial matrix Making high energy cofactor NAD+ to NADH to get energy farther Other fuels: palmitate is a fatty acid Citric acid cycle GTP GDP: like ATP, it is a high energy cofactor Proteins Proteins do not function in isolation Location of protein complexes on membrane is important for getting energy of out glucose Oxidative phosphorlyation Tke energy from reduced compounds and oxidize reduced compounds in electron transport chain
At each step, a little G is drawn off Used to drive proton into the intermembrane space Falls back into inner membrane through ATP synthase to make ATP (outer/inter/inner)