chapter 8

• Every energy transfer increases entropy (disorder) of the universe
• Catabolic pathways release energy by breaking down complex molecules into simpler compounds
• Anabolic pathways consume energy to build complex molecules from simpler ones
• Bioenergetics is the study of how energy flows through living organisms
• catabolic starts with complex molecules and makes them simpler anabolic starts with simple molecules and makes them complicated
• Thermal energy is the kinetic energy associated with the random movement of molecules, and is called heat when moved from one object to another
• Chemical energy is the potential energy available for release in a chemical reaction
• Complex molecules are high in chemical energy because energy is released as they are broken down to simpler products
• First law of thermodynamics

  the energy of the universe is constant
• Second law of thermodynamics

  every energy transfer loses energy (typically in the form of heat)
• Free energy equation

  $ΔG=$$ΔH-TΔS$
• Only processes with a negative ∆G are spontaneous
• Free energy is the portion of a system’s energy that can do work when temperature and pressure are uniform throughout the system, as in a living cell
• ΔG represents the difference between free energy of the final state and the free energy of the initial state ΔG=Gf-Gi
• What does the lose of free energy mean for the system?

  That it becomes more stable
• In spontaneous change the free energy of the system decreases (∆G < 0) and the system becomes more stable. The released free energy can be harnessed to do work
• exergonic vs. endergonic

  exergonic is a net release of energy from the system

  endergonic is a net absorbtion of energy by the system
• Reactions in a closed system eventually reach equilibrium and then do no work, that is why open systems are used for hydro-electricity.
• Competitive enzyme inhibitors are substrates that are competing for the same active site on the enzyme
• Enzyme names normally end in -ase
• Induced fit of a substrate brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction
• The active site is a region of the enzyme that substrates bind to
• Molecule(s) that has a specific shape to bind to enzymes and be shaped into different products

  Substrate
• Allosteric regulation occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site (check ch 8 slide 44 for more)
• In feedback inhibition, the end product of a metabolic pathway shuts down the pathway
• A reaction that occurs spontaneously, not requiring any energy is exergonic while a reaction that requires energy is endergonic.
• How does the phosphorylation of glutamic acid (Glu) provide energy for the rest of the reaction to occur?

  The addition of a phosphate to Glu forms a phosphorylated intermediate with more free energy than Glu. The ammonia can thus displace the phosphate in an exergonic reaction
• What is the ΔG of ATP hydrolysis?

  -7.3 Kcal/mol
• A chemical reaction is the making or breaking of bonds that changes the composition of matter
• Which process in the body converts energy found in glucose into energy stored in ATP?

  Cellular respiration
• Heat, carbon dioxide, and water are all by-products of cellular respiration
• cellular respiration is a catabolic pathway
• ATP is made up of three phosphates, a ribose sugar, and adenine
• What happens to the phosphate group that is removed when ATP is converted to ADP?


  It is acquired by a reactant in an endergonic reaction. 
• What is energy coupling?

  the use of energy released from an exergonic reaction to drive an endergonic reaction
• Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?

  γ-phosphate (the terminal phosphate)
• As a result of its involvement in a reaction, an enzyme is uncharged
• The final product of a metabolic pathway is usually the compound that regulates the pathway.