Chapter 8 Packet


Totality of an organism's chemical reaction; emergent property of life that arises from interactions between molecules within the orderly environment of the cell


metabolism


There are two types of reactions in metabolic pathways: __ + ___


anabolic and catabolic


Which reactions release energy?


catabolic


Which reactions consume energy?


anabolic


Which reactions build up larger molecules?


anabolic


Which reactions break down molecules?


catabolic


Which reactions are considered uphill?


anabolic


Which type of reaction is photosynthesis?


anabolic


What type of reaction is cellular respiration?


catabolic


Which reactions require enzymes to catalyze reactions?


anabolic


Contrast kinetic energy and potential energy?


Kinetic energy- associated with motionpotential energy- energy that's stored and can later be used to do cell work


Which type of energy does water behind a dam have?


potential energy


What type of energy does a mole of glucose have?


chemical energy


__ is the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell.


free energy


What is the symbol for free energy?


triangle G


For an exergonic reaction, is *triangle* G negative or positive?


negative


Is cellular respiration an endergonic or an exergonic reaction? Why


exergonicit is breaking down molecules


What is *triangle* G for cellular respiration?


-686 kcal/mol (-2870 kJ/mol)


Is photosynthesis endergonic or exergonic? Why?


endergonicit requires solar energy to start the process


What is the energy source that drives photosynthesis?


from the environment by capturing light and converting its energy to chemical energy


If energy is released, *triangle* G must be what?


exergonic


List the three main kinds of work that a cell does. Give an example of each.


chemical- synthesis of polymers from monomerstransport- active transport (pumping of substances across membranes against the direction of spontaneuous movement)mechanical- beating of cilia, contraction of muscle cells, movement of chromosomes during cell division (reproduction)


In ATP molecules, what bonds are likely to break?
By what process?


bonds between phosphate groupshydrolysis


List all the molecules that make up ATP


contains ribose with nitrogenous base adenine and a chain of three phosphate groups bonded to it


What does ATP stand for?


adenine triphosphate


When the terminal phosphate bond is broken, a molecule of inorganic phosphate Pi is formed, and energy is ________.


released


For this reaction ATP ----> ADP +Pi, *triangle* G is ____.
Is this reaction endergonic or exergonic?


-7.3 kcal/mol (-30.5 kJ/ mole)exergonic


The use of an exergonic process to drive an endergonic one; key feature in the way cells manage their energy resources


energy coupling


In many cellular reactions, a phosphate group is transferred from ATP to some other molecule in order to make the second less stable. The second molecule is said to be __________.


phosphorylated


If you could not regenerate ATP by phosphorylating ADP, how much ATP would you meed to comsume each day?


You'd use up nearly your body weight in ATP each day.


A chemical agent that speeds up a reaction without being consumed by the reaction


catalyst


amount of energy needed to push the reactants over an energy barrier, or hill, so that the downhill part of the reaction can begin; energy required to contort the reactant molecules so the bonds can break


activation energy (EA)


What effect does an enzyme have on EA?


lowers EA barrier, enabling the reactant molecules to absorb enough energy to reach the transition state even at moderate temperatures.


How is *triangle* G affected by the enzyme?


it is unaffected; it cannot change an endergonic reaction to an exergonic one; they only hasten reactions that woul doccur eventually anyway


macromolecule that acts as a catalyst


enzyme


reactant an enzyme acts on


substrate


specific portion of an enzyme that binds the substrate by means of multiple weak interactions and that forms the pocket in which catalysis occurs


active site


material resulting from a chemical reaction


products


the change in shape of the active site of an enzyme so that it binds more snugly to the substrate


induced fit


Describe four mechanisms enzymes use to lower activation energy?


1. In reactions involving two or more reactants, the active site provides a template on which the substrates can come together in proper orientation for a reaction to occur between them2. As the active site of an enzyme clutches the bound substrates, the enzyme may stretch the substrate molecules toward their transition-state form, stressing the bonding critical chemical bonds that must be broken during the reaction3. The active site may provide a microenvironment that is more conducive to a particular type of reaction than the solution itself would be without the enzyme4. Direct participation of the active site in the chemical reaction


What are some factors that affect the rate of enzyme action?


initial concentration of substratepHtemperaturecofactorsenzyme inhibitors


Explain how initial concentration can affect the rate of enzyme action.


the more substrate molecules that are available the more frequently they access the active sites of the enzyme molecule. However there is a limit.


Explain how temperature and pH affect the rate of enzyme action.


Enzymes have optimal conditions. Many have 35-40o C and a pH of 6-8. However, there are some exceptions.


___ affects the rate of enzyme activity because substrates collide with active sites more frequently when molecules move rapidly.


Increase in temperature- optimal temperature


Why can extremes of pH or very high temperatures affect enzyme activity?


The can denature the enzyme, making it biologically inactive.


Name a human enzyme that functions well in pH 2. Where is it found?


pepsinhuman stomach as a digestive enzyme


nonprotein molecule or ion that is required for the proper functioning of an enzyme; can be permanently bound to the active site or loosely with substrate during catalysis


cofactor


organic molecules serving as enzymes, such as vitamins


coenzymes


substances that reduce the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics


competitive inhibitor


substances that reduce activity of enzymes by binding to a location remote from the active site, changing the enzyme's shape so that the active site no longer functions effectively


noncompetitive inhibitor


term used to describe any case in which a protein's function at one site is affected by the binding of a regulatory molecule to a separate site


allosteric regulation


What is the difference between an allosteric activator and an allosteric inhibitor?


activator- binds to regulatory sitre, stabilizing the shape that has functional active sitesinhibitor- binding stabilizes the inactive form of an enzyme