Test 1 Energy The Capacity For Work Work force X distance Bioenergetics flow and exchange of energy within a living system First law of thermodynamics matter cannot be created nor destroyed but transforms from one form to another without being depleted Energy system in the body o Chemical energy mechanical energy heat o Body does not produce consume or use up energy instead it transforms it from one state into another as physiologic systems undergo continual change Potential and Kinetic Energy metabolism Potential energy bound energy i e macronutrient before releasing its stored energy in o Releasing potential energy transforms into kinetic energy of motion Biosynthesis specific building block atoms of C H O and N become activated and join other atoms and molecules to synthesize important biologic compounds and tissues Energy Releasing and Energy Conserving Processes Exergonic any physical or chemical process that releases frees energy to its surroundings downhill process o G H TS G free energy H enthalpy potential energy within a molecule s chemical bonds S energy unavailable due to randomness T absolute temperature deg C 273 Endergonic store or absorb energy uphill proceeds with an increase in free energy Changes in free energy occur when bonds in reactant molecules form new product for biologic work molecules with different bonding o G H T S Second law of thermodynamics the tendency of potential energy to degrade to kinetic energy of motion with a lower capacity for work i e increased entropy o Entropy the inertia that makes a thermodynamic process more likely to occur the higher the entropy the higher the disorder o The entropy of an isolated system never decreases because isolated systems spontaneously evolve towards thermodynamic equilibrium Interconversions of Energy Even under favorable conditions the net flow of energy in the biologic world moves toward entropy ultimately producing the LOSS of potential energy o The entire system always shows a net increase in energy entropy Forms of energy o Chemical fossil fuel oil burner o Mechanical hydroelectric generating plant o Heat solar panels o Light sun Test 1 o Electrical electrical energy o Nuclear reactor Examples of Energy Conversions Photosynthesis and respiration represent the most fundamental examples of energy conversion in living cells Photosynthesis sun gamma radiation radiant energy pigment of chlorophyll absorbs radiant energy synthesizes glucose from CO2 and H2O release of O2 Endergonic process G o Solar energy coupled with photosynthesis powers the animal world with food and oxygen Respiration exergonic reaction reverse of photosynthesis G o Glucose 6O2 6CO2 6H2O ATP Biologic Work in Humans Mechanical work muscle contraction o Directly convert chemical energy into mechanical energy o i e cilia or contractile elements to facilitate cell division non obvious mechanical work Chemical work synthesizes cellular molecules o Maintenance and growth continuous synthesis of cellular components takes place as others break down Transport work concentrates substances in the intracellular and extracellular fluids o Active transport describes energy requiring process Factors that Affect the Rate of Bioenergetics Enzymes and coenzymes greatly alter the rate of energy release during chemical reactions Types o Oxidoreductases catalyze oxidation reduction reactionss where the substrate oxidized is regarded as hydrogen or electron donor i e dehydrogenases oxidates oxygenases reductases peroxidases hydroxylases o Transferases catalyzes the transfer of a group from one compound donor to another acceptor i e kinases transcarboxylases transaminases o Hydrolases catalyzes reactions that add water i e esterasess phosphatases peptidases o Lyases catalyze ractions that cleave C C C O C N and other bonds by other means than by hydrolysis or oxidation i e synthases deaminases decarboxylases o Isomerases catalyze reactions that rearrange molecular structure i e isomerases and epimerases o Ligases catalyze bond formation between two substrate molecules with concomitant hydrolysis of the diphosphate bond in ATP or a similar triphosphate Test 1 Enzymes as Biologic Catalysts i e pyruvate carboxylase Enzymes highly specific and large protein catalysts that accelerate the forward and reverse rates of chemical reactions without being consumed or changed in the reactions o Reduce the required activation energy energy input to initiate reaction o For an uncatalyzed reaction to proceed the reactant must have a HIGHER free energy level than the product meal might take 50 years Fun fact Without enzyme action the complete digestion of a breakfast o Enzymes are not altered in reactions and may be reused o A single mitochondria may contain up to 10 billion enzyme molecules o Lock and key mechanism ensures that the correct enzyme mates with its specific substrate to perform a particular function conformational change in enzyme will then occur Enzyme turns on where its active site joins in a perfect fit with the substrates active o Forms enzyme substrate complex Mode of Action site Coenzymes Some enzymes remain dormant unless activated by coenzymes o Coenzymes nonprotein organic substances facilitate enzyme action by binding the substrate with specific enzyme Enzyme inhibitors substances inhibit enzyme to slow rate of reaction o Competitive inhibitors resemble the structure of a normal substrate for an enzyme bind to enzyme s active site but the enzyme cannot change them blunts intreraction with real substrate o Noncompetitive inhibitor do not resemble enzyme s substrate and do not bind to its active site they bind to enzyme at site other than active site changes enzyme s structure and ability to catalyze reaction Hydrolysis Splits bonds by adding H and OH to reaction byproducts Digestion of starches and disaccharides Condensation or I like to call it dehydration Reactions of hydrolysis can occur in opposite direction Structural components of nutrients bind together in condensation reaction to form more complex molecules and compounds i e peptide bond Oxidation and Reduction Reactions The linking coupling of oxidation reduction redox reaction enables oxidation a substance loses electrons to coincide with the reverse reaction of reduction a substance gains electrons o Remember LEO the lion says GER Test 1 Lose Electrons Oxidized Gain Electrons Reduction Measuring Energy Release in Humans The transport of electrons by specific carrier molecules constitutes
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