STUDY GUIDE ENERGY METABOLISM AND ENYMES CHAPTER 6 BS161 Section 3 Dr Osteryoung Spring 2015 Use the concepts in this chapter as a foundation for understanding the processes of respiration and photosynthesis covered in chapters 7 and 8 Also consider how these principles apply to processes we ve covered in chapters 3 5 particularly to active and passive transport and to synthesis and breakdown of macromolecules By the time you re done studying you should be able to answer all the questions and explain the terms and their signi cance for biolog ical systems on your own and in your own words without the aid of books or notes Answer the end of chapter quiz questions The Big Picture for Chapters 6 8 can be summed up in the following questions What is energy Why do cells need energy Where does energy needed for life come from How do cells convert energy from one form to another How is energy harnessed by cells to do work What kinds of work do cells need to do Discuss these questions in general terms as they relate to metabolic processes required for life Come back and discuss these again after we cover chapters 7 and 8 Energy is the capacity to do work Cells need energy to complete metabolic processes Ultimately the energy for life comes from the sun Cells convert energy from one for to another Explain the role of catabolic and anabolic pathways in cellular metabolism Anabolic pathways use up energy to build up macromolecules catabolic pathways harvest energy to break down macromolecules fats sugars etc Explain what the term metabolism means What is a metabolic pathway What is a meta bolic network Metabolism the total of all chemical reactions carried out by an organism Metabolic pathway biochemical pathway the product of one reaction is the substrate for the next Metabolic network the sum of all the metabolic processes including anabolic catabolic processes and biochemical metabolic pathways What are potential energy kinetic energy and heat What are some examples of each rele vant to biological systems Potential energy stored energy ex Glucose which is a 6 carbon sugar has potential en ergy held or stored within its bonds that have not yet been broken down to release energy recall from chapter 3 that the breakage of bonds releases energy Kinetic energy the energy of motion ex the contraction of leg muscles to push bike pedals Explain in your own words the First and Second Laws of Thermodynamics How do they relate to energy transformations that occur during metabolism 1st Law old Thermodynamics The energy in the universe is constant energy CANNOT be made or destroyed This means that energy can only be converted into differ ent types such as potential being converted to kinetic energy or into chemical en ergy 2nd Law of Thermodynamics Disorder is more likely then order i e a wooden shelf is more likely to fall and break into separate pieces of wood than separate pieces of wood are likely to build them selves into a shelf What does change in free energy mean Change in free energy symbolized by G a change in the energy available to break or form bonds in any system which results from reactions which may break bonds in reactants to form products Simply put a change in free energy is a change in the amount of energy available to do work in any system Distinguish between exergonic and endergonic reactions Endergonic requires input of energy NOT Spontaneous G is POSITIVE G 0 Move reaction AWAY from equilibrium energetically UNFAVORABLE Exergonic releases energy Spontaneous G is NEGATIVE G 0 Move reaction TOWARD equilibrium energetically FAVORABLE How do the terms exergonic energy releasing negative G G 0 spontaneous energeti cally favorable endergonic non spontaneous positive G G 0 energy requiring and en ergetically unfavorable relate to one another The point is that many of these terms mean the same thing and can be used interchangeably KNOW THESE TERMS CAN BE USED INTERCHANGEABLY How do these terms relate to the capacity for work and energy coupling in the cell What is energy coupling Exergonic reactions can do work This is because they produce the energy needed for car rying out endergonic reactions Energy coupling the transfer of energy form exergonic reactions to power endergonic reactions ex ATP hydrolysis an exergonic reactions releases energy which is then used for the formation of ATP an endergonic process that requires energy What does G 0 mean What does equilibrium mean What does this have to do with the capacity for a process to be used for cellular work G 0 means that a cell is at equilibrium which is a state of balance This means that all in fluences of any reactions in the cell are balanced When this occurs the cell can not carry out processes The cell would not be able to do work What are some examples of nonequilibrium unstable conditions that frequently exist in cells Why is it important that such conditions be maintained What would happen if all conditions in the cell came to equilibrium Why Example The higher concentrations on Na outside the cell and a lower concentration on the inside of the cell Importance Non equilibrium conditions allow for electrochemical gradients and other gra dients that can produce energy needed by the cell to accomplish other task such as the in the Na glucose cotransporter The energy from the Na moving down its concentration gradient provides the energy necessary for the cell to move glucose into the cell against its concentration gradient If all conditions in the cell came to equilibrium no reactions would be able to occur ATP couldn t be produced or broken down redox reactions could not occur electron transport would stop etc and the cell would not function Simply put the cell would not be able to perform work Explain in your own words the relationship between equilibrium and free energy change G for a chemical reaction Do the same for a transport When G 0 then the reaction is exergonic G 0 the reaction is endergonic G 0 the reaction is at equilibrium Active transport recall from chapter 5 that this type of transport requires energy which means that it is an endergonic process Passive transport recall from ch 5 that this type of transport releases energy and it happens naturally or spontaneously going from areas of high concentration to areas ow concentration which makes this an exergonic process Passive transport includes diffusion facilitated diffusion and osmosis Which of the above terms see asterisk above would apply to the following