<p>METABOLISM: Greek: to change The chemical rxns taking place w/in a cell Catabolism: breaking down molecules to generate E Anabolism: construction of larger molecules (e.g. protein synthesis) and using E Often coupled, see below</p><p>Living things require Energy</p><p>Energy = capacity to do work</p><p>Potential: stored E, ball at top of hill Kinetic: E of motion, ball rolling down hill</p><p>Food consumed is chemical E as Potential converted to Kinetic as mechanical</p><p>Laws of Thermodynamics First: E cannot be created or destroyed but can be converted from one form to another Conservation of E Second: changing forms of E results in a loss of E – increasing disorganization = Entropy Cellular E transformations (e.g. Na / K pump) result in loss of E Heat is the least organized form of E</p><p>Diffusion releases E as solute becomes randomly distributed Glucose hydrolysis results in more, smaller, and more stable molecules</p><p>Are living things not examples of increased order, rather than disorder? At an E cost Macromolecules a cell builds will, over time, tend to break down, but slowly at cell temp</p><p>Potential = stored Chemical Kinetic = motion Mechanical</p><p>Free E = G = part of a system’s E available for work at constant temp A measure of instability</p><p>G = H – TS H=total E, S=entropy, T=temp, Kelvin Energy Transformation Exergonic Reaction: E released, negative delta G Reaction will happen spontaneously, no outside help But often requires help at biological temperatures Free E, G, released, therefore, delta G is negative Water flows downhill Endergonic Rxn: E required, positive delta G Protein synthesis, muscle contraction, an “uphill” process Equilibrium: delta G = 0</p><p>Glucose, MW = 180g, -686kcal / mol Mole: # grams comprising a molecule’s (or atom’s) MW (or atomic weight) in daltons. Avogadro’s number, 6.023 X 10^23</p><p>ATP: the universal E currency of Biology Which class of macromolecules does this belong to? Adenine (N base), Ribose, 3 Phosphates Used in many rxns, provides the required amount of E for many biological functions Used to do work: Chemical: synthesize macromolecules for cell function Transport: of compounds across membranes Mechanical: contraction, movement The triphosphate bond is not strong resulting in available E, it is weak, a loaded spring</p><p>Metabolic Pathways Because delta G = 0 at eq, a cell maintains some diseq thru metabolic pathways Product of one rxn becomes substrate of next, along a sequence = pathway Respiration: a series from glucose to CO2 A steady intake of glucose and ability to release CO2 will maintain pathway</p><p>Enzymes: catalyze, enhance speed, of these reactions by lowering Ea Many respiratory rxns are coupled Activation Energy, Ea, or delta G++ A rxn involves breaking molecular bonds and forming new ones Requires an initial E investment, Ea Transition state Heat will favor formation of more stable bonds and release of E, but can kill cells Ea is lowered in presence of an enzyme A spark plug Doesn’t change delta G, does not induce spontaneity</p><p>Enzymes Are specific to rxns, have shapes with active sites specific to substrate Induced fit and generally held by H bonds May result in degradation of one molecule or rxn between 2 or more Catalysis happens at ~1,000 molecules / second</p><p>Factors Affecting Speed of Enzyme Activity [substrate], pH, temp, salinity, cofactors, inhibitors Cofactor – inorganic Coenzyme – organic, e.g. vitamins Inhibitors: reversible and irreversible, based on bond types Competitive: at active site Noncompetitive: at another site on enzyme, allosteric site Can be activators or deactivators Can be poisons: DDT, parathion, penicillin Feedback Inhibition: metabolic pathway switched off by products Phosphorylation (e.g. Na / K pump), can activate enzymes and involve E input Some hormones are detected by membrane receptor proteins and P-late enzymes</p><p>Enzymatic catalyzed rxns tend to happen in specific locations w/in cell It’s not a random series of reactions w/o order Oxidation / Reduction Oxidation: loss of e- Reduction: gain of e- Photosynthesis reduces CO2 and oxidizes H2O to form glucose and O2 CO2 + H2O + E  glucose + O2 NADP+ is photosynthesis coenzyme aiding oxidation and reduction of substrates and products Respiration is the reverse, glucose oxidized, O2 reduced, forming CO2, E, and water NAD+ is respiration coenzyme</p><p>Electron Transport Series of carriers transferring an initial high E e- to a final low E e-, and generating ATP Carriers are reduced and then oxidized during e- transport steps. Occurs in thylakoids and cristae Results in a buildup of protons during redox and an electrochemical gradient Proton pump and ATP synthase are membrane proteins Chemiosmosis: ATP generation by ATP synthase and proton gradient</p><p>Emergent Properties We’ve seen chemistry of macromolecules Cell and cell membrane structures Peculiar properties of water None is simply the sum of its parts</p>