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Metabolism and Energy I. Metabolism and Energy Metabolism- the totality of an organism’s chemical reactions Catabolism Catabolic pathways - break down compounds Anabolism Anabolic pathways- build up compounds Energy Provides the ability to do work Potential Energy The energy stored in an object Carbohydrates and lipids Enthalpy – energy stored in bonds of a molecule Covalent bonds = stored potential energy Nutrients (carbohydrates etc.) have energy (calories) in their bonds Kinetic Energy The energy of a moving object When food energy is released it turns into kinetic energy of molecules Eg. Burning, metabolism Calorie One calorie is the ENERGY required to raise 1 gram of water 1 degree C Nutrition calories are Kilocalories and will raise 1 Liter of water 1 degree C 1000 calories = 1 Calorie = 1 kcal 2 regular water bottles = 1 liter raised 1 degree C Calorimeter measures calories Food is Burned! Water temp rise measured Thermodynamics Thermo = heat Dynamics = changes The study of changes in energy and heat First Law of Thermodynamics “Conservation of Energy” . Energy can NOT be created or destroyed, but it can be changed E=MC2 Does Einstein's equation contradict the law of conservation of energy? In a nuclear reaction Matter converts to energy, but is still conserved Energy transformation Living things must transform energy into usable form. Sugar ATP Second Law of thermodynamics Systems tend to change in a way that tends to increase disorder. Disorder of universe is increasing! “Entropy” = order disorder Entropy is a fact of Life "Now, in the second law of thermodynamics..." reproduced with permission, Copyright © by Sidney Harris Entropy affects everything Entropy happens Life – combats entropy Living things have complex organization and systems to combat entropy Heat Entropy most commonly takes the form of heat loss where energy is spread out Non living and dead things lose energy quickly as HEAT loss Free Energy Energy that is carefully stored for further use Living things “burn” calories to produce free energy compounds Sugar + Oxygen carbon dioxide + ATP A wolf produces heat and free energy Free energy potential Energy released Unstable More free energy Less entropy Stable Less free energy More entropy Decomposition reaction Energy is released Energy released C6H12O6 more E CO2 + H20 less E Δ G = change in (Δ) Free energy (G) G = Gibbs free energy limits the system energy to the cell Equation for change in free energy ΔG = Δ G2 – Δ G1 Free energy = final energy – initial energy ΔG determines reaction Neg - ΔG spontaneous Pos + ΔG not spontaneous Endergonic vs. exergonic reactions Endergonic = + ΔG needs Energy to occur stores energy in products Exergonic = - ΔG releases Energy. Products have less energy Exergonic ex. Uses up free energy Energy C6H12O6 + O2 ΔG -686 kcal/mol CO2 + H20 Ex. Endergonic requires free energy Energy 2H2 + O2 2H2O Energy required to synthesize water! + ΔG Free energy equation ΔG = ΔH – T ΔS ΔG= free energy ΔH = enthalpy energy in chemical bonds (Available energy) T = temperature (degrees Kelvin) ΔS = entropy (Unavailable energy) ATP Adenosine Tri Phosphate The energy “currency” of living things ATP Adenosine = Adenine + Ribose Tri = three Phosphate = 1 Phosphorus, 4 oxygens ATP stores FREE energy Sugar + Oxygen CO2 + H2O + ATP Free energy (ATP) is energy available for work in the body (muscles etc.) Phosphate bonds ATP’s energy is stored energy in Phosphate bonds ATP forms ADP Energy is released when the high energy Phosphate bond is broken Hydrolysis of ATP ATP + H2O ΔG = -7.3 kcal/mol ---- Exergonic!! ADP + Pi Happens spontaneously – can be used to power cell reactions Cellular work requires ATP The free energy released from ATP can be used to do work Needed by endergonic reactions Without Free energy Energy is lost as heat Cellular work requiring ATP A) Mechanical work – moving cilia, muscle contraction, moving chromosomes B) Transport work – Active transport C) Chemical work – Non-spontaneous reactions Energy coupling The use of an exergonic reaction to push an endergonic reaction Without ATP A + B ΔG = 3.4 kcal/mol Endergonic NEEDS ENERGY AB With ATP 1) ATP + A P A + ADP 2) A A+B ATP P + AB P B AB + ΔG = 3.4 ΔG = -7.3 ΔG = -3.9 EXERGONIC! P Redox reactions These are also coupled reactions. Oxidation of one molecule, such as ATP, supplies energy to reduce another molecule Oxidation – loss of electrons. Exergonic Reduction – gain of electrons. Endergonic