Bio Unit 4 Enzymes

___ is responsible for ____modt ___ in cells and in most cases it acts as the ____that powers ____ ATP (adenosine triphosphate) contains the what components In addition to its role in _____, ATP is also one of the nucleoside triphosphates used to ____ The bonds between the phosphate groups of ATP can be When the terminal phosphate bond is ____ by the addition of ____, a molecule of _____ This is how...this reaction is ,...and releases ____ of energy .. In the cell, conditions do not conform to _____, primarily because reactant and product concen- trations Because their hydrolysis ____ energy, the phosphate bonds of ATP are sometimes referred to as The phosphate bonds of ATP are not ______, as "high-energy" may imply; rather, the reactants ( The ___ of energy during the hydrolysis of ATP comes from the _____ to a state of _____, not from the ____s themselves. ATP is useful to the cell because the. But why does this hydroly- sis release so much energy? If we reexamine the ATP molecule in Figure 6.8a, we can see that all three . The triphosphate tail of ATP is the chemical equivalent of a When ATP is hydrolyzed in a test tube, the release of free energy merely . In an organism this same generation of heat can for instance, the process of shivering uses In most cases in the cell, however, the generation of heat alone would be . Instead, the cell's proteins ____ the energy ____ in . For example, with the help of specific ___, the cell is able to use ______ If the AG of an endergonic reaction is less than the amount of energy released by ATP hydrolysis, then . This usually involves ____, the transfer of a _____ from __ to The recipient with the phosphate group covalently bonded to it is then

ATP, mediating most energy coupling in cells, immediate source of energy that powers cellular work. sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups bonded to it energy coupling make RNA broken by hydrolysis broken a water molecule, a molecule of inorganic phosphate (HOPO, which is abbreviated throughout this book) leaves the ATP. In this way, adenosine triphosphate becomes adenosine diphosphate , or ADP. this reaction is exergonic and releases 7.3kcal of energy per mol of ATP hydrolyzed—This is the free-energy change measured under standard con ditions standard conditions, differ from 1 M. releases, high-energy phos- phate bonds, but the term is misleading. unusually strong bonds.. (ATP and water) themselves have high energy relative to the energy of the products (ADP and inorganic phosphate) release, chemical change, lower free energy, phosphate bonds energy it releases on losing a phosphate group is somewhat greater than the energy most other molecules could deliver three phosphate groups are negatively charged. These like charges are crowded together and their mutual repulsion contributes to the instability of this region of the ATP molecule compressed spring heats the surrounding water sometimes be beneficial. ATP hydrolysis during muscle contraction to warm the body. an inefficient (and potentially dangerous) use of a valuable energy resource harness the en- ergy released during ATP hydrolysis in several ways to per- form the three types of cellular work-chemical, transport and mechanical enzymes the energy released by ATP hydrolysis directly to drive chemical reactions that, by themselves, are endergonic u the two reactions can be coupled so that, overall, the coupled re- actions are exergonic phosphorylation, phosphate group, from ATP to some other molecule such as the reactant called a phosphorylated intermediate.

How enzyme concentration affects enzyme activity -as increase enzyme, -more enzymes equals -reaction rate —-off substrate becomes a not all enzyme molecules cna How substrate concentration affects enzyme activity -as increase substrate, -more substrate equals -eventually reaction rate -all enzymes eventually have -enzyme is —— -reached the —— rate of reaction Temperature -Optimum T° Heat: increase ●increased —- of molecules disrupts -denaturation = Cold: ●molecules move ●decrease —-between

Enzyme concentration ●as increase enzyme = increase reaction rate ●more enzymes = more frequently collide with substrate ●reaction rate levels off ●substrate becomes limiting factor ●not all enzyme molecules can find substrate ●as substrate = reaction rate ●more substrate = more frequently collide with enzyme ●reaction rate levels off ●all enzymes have active site engaged ●enzyme is saturated ●maximum rate of reaction greatest number of molecular collisions ●human enzymes = 35°- 40°C ●body temp = 37°C beyond optimum T° energy level disrupts bonds in enzyme & between enzyme & substrate(H, ionic = weak bonds) lose 3D shape (3° structure) decrease T° slower collisions between enzyme & substrate

Chemical enery Law of thermodynamics is the study of Goes chemical to 1st Law: 2nd Law:. Life requires a lack of Life is built on—— and transforming Metabolism -chemical Dehydration synthesis — - -____reactions Hydrolysis- - -____reactions Some chemical reactions ___ energy -ex -____=____ Some chemical reactions require -these are -ex -___=_____

Potential energy available for release in chemical reaction energy transformations potential energy, most lost as heat Energy can be transferred and transformed but it can't be created or destroyed. Every energy transfer or transformation increases the entropy of the universe entropy (btw more entropy, less energy needed to maintain) chemical reactions, energy from one form to another reactions of life ●dehydration synthesis forming bonds between molecules ●synthesis ●anabolic reactions ●breaking bonds between molecules ●digestion ●catabolic reactions release-exergonic digesting polymers hydrolysis equals catabolism input if energy endergonic -exbuilding polymers -dehydration synthesis = anabolism

___,____, and other ____ molecules are rich in ____ and have the potential to ______ . These molecules persist only because at temperatures typical for cells, few The barriers for selected reactions must occasionally be ____, however, for cells to _____ Heat can ____ the rate of a reaction by allowing reactants to ___, but this wouldn't ___ in ___ systems First, high temperature ____ and __ cells .Second, heat would ____ not just ____ Instead of heat, organisms carry out ___- a process by which a____ does what?? An enzyme ____n by _____, enabling the reactant molecules to . An enzyme cannot change the ___! it can't En zymes can only ____ that would eventually ___, but this enables the cell to have a explain transition state

Proteins, DNA, and other complex cellular, free energy, decompose spontane- ously; that is, the laws of thermodynamics favor their break- down f ew molecules can make it over the hump of activation energy. surmounted, carry out the processes needed for life. increase reactants to attain the transition state more often, but this would not work well in biological sys- tems. denatures proteins and ills cells speed up all reactions, not just those that are needed. catalysis.. catalyst (for example, an enzyme) selec- tively speeds up a reaction without itself being consumed catalyzes a reaction lowering the EA bar rier, enabling the reactant molecules to absorb enough energy to reach the transition state even at moderate temperature delta G for a reac- tion; it cannot make an endergonic reaction exergonic. hasten reactions that would eventually occur anyway, but this enables the cell to have a dynamic metabo- lism, routing chemicals smoothly through metabolic pathways. The reactants AB and CD must absorb enough energy from the surroundings to reach the unstable transition state, where bonds can break. After bonds have broken, new bonds form, releasing energy to the surroundings.

Catalysts reduce they reducing the amount of So what's a cell got to do to reduce activation energy? Enzymes are biological They are ___(and—-) They facilitate They increae—- without being They reduce the they DO NOT change the They are required for most They're highly ____ There are thousands of Thry control the reactions of Substrate enzyme substrate complex is a

Reducing Activation energy energy to start a reaction get help! ... chemical help... ENZYMES ●Biological catalysts ●proteins (& RNA) ●facilitate chemical reactions ●increase rate of reaction without being consumed ●reduce activation energy ●don't change free energy (G) released or required ●required for most biological reactions ●highly specific ●thousands of different enzymes in cells ●control reactions of life ●reactant which binds to enzyme ●enzyme-substrate complex: temporary association

To reach the contorted state where bonds ____,reactant molecules must When the new bonds of the product molecules form, energy is____ and the molecules _____-is known as the free energy of activation, or activation energy, abbreviated EA in this book. We can think of activation energy as the ____ needed to . Activation energy is often supplied by ___ in the form of ____that the reactant molecules The absorption of ___ energy ____ the reactant molecules so that they . It also agitates the ____, making the break age of bonds____. When the molecules have ____ enough energy for the _____, the reactants are in an ___ condition known as the The activation of the reactants is represented by the g. At the summit, when energy equivalent to___ has been ____, the reactants are in the They are ___ and their bonds can be As the atoms then settle into their new, more ____, energy is This corresponds to the ____ part of the curve, which shows the . The overall decrease in ____ means that EA is ___ with ___!!!! ⭐️ The reaction shown in Figure 6.12 is ___ and oc- curs spontaneously (AG< 0). However, the activation energy provides a ___ that determines the The reactants must ___ before the reaction can occur. For some reactions, ___ is modest enough that even at room temperature there is ____ for many of the reactant molecules to In most cases, however, Ea is so ___ that in these cases, the reaction will occur at a noticeable rate only if For example, the reaction of gasoline and oxygen is ____ and will occur spor ously, but ___ is required for

can change, absorb energy from their surroundings is re- leased as heat, and the molecules return to stable shapes with lower energy than the contorted state. The initial investment of energy for starting a reaction- the energy required to contort the reactant molecules so the bonds can break amount of energy needed to push the reactants to the top of an energy barrier, or uphill, so that the "downhill" part of the reaction can begin heat, thermal energy , absorb from the surroundings. thermal, accelerates the reactant mol ecules, so they collide more often and more forcefully atoms within the molecules, more likely absorbed, bonds to break, unstable condition known as the transition state. uphill portion of the graph, in which the free-energy content of the reactant molecules is increasing Ea has been absorbed, transition state They are activated, and their bonds can be broken. stable bonding arrangements, energy is released to the surround- ings. downhill loss of free energy by the molecules free energy repaid with dividends, as the formation of new bonds releases more energy than was invested in the breaking of old bonds exergonic barrier that determines the rate of the reaction T absorb enough energy to reach the top of the activation energy barrier before the reaction can occur Ea sufficient thermal energy for many of the reactant molecules to reach the transition state in a short time high and the transition state is reached so rarely that the reaction will hardly proceed at all energy is provided, usually as heat. exergonic energy is required for the molecules to reach the transition state and react.. Only when the spark plugs fire in an automobile engine can there be the explosive release of energy that pushes the pistons. Without a spark, a mixture of gasoline hydrocarbons and oxygen will not react because the EA barrier is too high.

Energy is capacity to energy is important in every day life bc Energy is the ability to ___ a collection of energy exists in various forms, and work of life depend on Energy can be associated with the relative Moving objects can perform work by Thermal energy ___ is also type of energy harnessed to perform work An object not presently moving may still Energy that is not kinetic is Molecules possess energy bc of Chemical energy catabolic oathways ____ energy by During a catabolic reaction, some bonds This transformation also occurs in the describe a similar reaction w food molecules Biochemical pathways, carried out in the context of

cause change some forms of energy can be used to do work-move matter against opposing forces rearrange, matter ability of cells to transform energy from one form to another motion of objects ..KE imparting motion to other matter kinetic energy associated with random movement of atoms or molecules ..thermal energy in transport form one molecule to another is heat!!! light (ex powering photosynthesis) possess energy potential-energy matter containsi due to its location or structure arrangement of electrons in bonds btwn their atoms potential energy available for release in chemical reaction release enery by breaking down complex molecules, ..these complex molecules such as glucose are high in chemical energy are broken, others are formed, releasing energy and resulting in lower energy breakdown products engine of a car when the gasoline react explosively w oxygen, releasing the energy that pushes the pistons and producing exhaust. reaction of food molecules w oxygen provided chemical energy in biological systems, producing CO2 and water as waste products. cellular structures, enable cells to release chemical energy from food molecules and use energy to power life processes.

Another term that describes a state of maximum stability is At equilibrium, the forward and For a system at equilibrium, G . Any change from the equilibrium position will have a For this reason, systems never Because a system at equilibrium cannot ____ it cant . A process is spontaneous and can perform work only when it More free energy (____) - -greater In a spontaneous change: -Free energy of a system -System becomes -Released free energy can be Less free energy (___) -more ____ -less Unstable systems are ____-they have tendency to

chemical equilibrium. reverse reactions occur at the same rate, and there is no further net change in the relative concentration of products and reactants. is at its lowest possible value in that system.. can think of equilibrium as free energy valley positive AG and will not be spontaneous spontaneously move away from equilib rium. spontaneously change, it can do no work is moving toward equilibrium. Higher G -less stable -work capacity decreases (delta G less than 0) more stable harnessed to do work Lower G stable work capacity rich in free energy ...they have tendency to change spontaneously to a more stable state , and its possible to HARNESS this downhill change to perform work.

Such an acidic environment _____, but pepsin is ___ to maintain its In contrast, trypsin, a ____, has an optimal pH of — and would be —- in the stomach Many enzymes require ___ for ____ activity These adjuncts, called —-, may be ___ tightly to the ___ or . The cofactors of some enzymes are —-, such as . If the cofactor is an organic molecule, it is . Most vitamins are important in nutrition because they act as ___ or ____ Cofactors function in various ways, but in all cases where they are used, they perform a Certain chemicals selectively ___ the action of specific enzymes. Sometimes the inhibitor ____, in which case the ____ is ____ Many enzyme inhibitors, however, bind to the enzyme by . Some reversible inhibitors ____ and compete for These mimics, called _____, reduce the____ by This kind of inhibition can be overcome by ____ the ___ of ____ so that In contrast, noncompetitive inhibitors do not . Instead, they impede enzymatic reactions by ____ to . This interaction causes the enzyme molecule to ___ and ___ are often irreversible enzyme inhibi- tors. An example is —-, a nerve gas.. This small molecule binds —— to the —— of serine, which is found in the ——-, an enzyme important in the nervous system. Other examples include the ____ ___ and ____,, inhibitors of . Finally, many —- are inhibitors of specific . For instance, penicillin blocks Citing enzyme inhibitors that are metabolic poisons may give the impression that enzyme inhibition is .. In fact, molecules naturally present in the cell often ____ activating by acting as . Such —— inhibition-is essential to the

denatures most enzymes adapted to maintain its functional three-dimensional structure in the acidic environ- ment of the stomach digestive enzyme residing in the alkaline environment of the human intestine, 8 denatured nonprotein helpers for catalytic activ- ity. cofactors bound tightly to the enzyme as permanent residents, or they may bind loosely and reversibly along with the substrate inorganic, the metal atoms zinc, iron, and copper in ionic form referred to, more specifically, as a coenzym act as coenzymes or raw materials from which coenzymes are made. crucial chemical function in catalysis inhibit inhibitor attaches to the enzyme by covalent bonds, in which case the inhibition is usually reversible. weak interactions, and when this occurs, the inhibition is reversible resemble the normal substrate molecule and compete for admission into the active site competitive inhibitors, reduce the productivity of enzymes by blocking substrates from entering active sites. increasing the concentration of substrate so that as active sites become available, more sub- strate molecules than inhibitor molecules are around to gain entry to the sites directly compete with the substrate to bind to the enzyme at the ac tive site binding to another part of the enzyme change its shape in such a way that the ac- tive site becomes much less effective at catalyzing the conver- sion of substrate to product ( Toxins and poisons sarin, cova- lently to the R group on the amino acid serine, which is found in the active site of acetylcholinesterase, an enzyme important in the nervous system pesticides DDT and parathion, key enzymes in the nervous system antibiotics, enzymes in bacteria blocks the active site of an enzyme that many bacteria use to make cell walls. generally abnor- mal and harmful regulate enzyme activity by acting as inhibitor regulation-selective, control of cellular metabolism

Different enzymes function in pH- changes in pH adds or —— and disrupts ___,____,____ ●_____ protein optimal pH? ●most human enzymes = pH ●depends on ●pepsin (stomach) = pH ●trypsin (small intestines) = pH Salt Concentration -changes in -adds or removes -disrupts ____,____ -disrupts attractions btwn -___protein -enzymes are___ of extreme ___!! Compounds that help enzymes ●theyre called ______.. made of Cofactors: what are they? examples? bound wi Coenzymes ●what r they? ●bind ___or____to ●exs?

different organisms in different environments adds or remove H+, disrupts bonds, disrupts 3D shape, disrupts attractions between charged amino acids, affect 2° & 3° structure ●denatures protein 6-8 localized conditions 2-3 8 Salt concentration ●changes in salinity ●adds or removes cations (+) & anions (-) ●disrupts bonds, disrupts 3D shape ●disrupts attractions between charged amino acids ●affect 2° & 3° structure ●denatures protein ●enzymes intolerant of extreme salinity ●Dead Sea is called dead for a reason! Activators.. cofactors and coenzymes non-protein, small inorganic compounds & ions ●Mg, K, Ca, Zn, Fe, Cu WITHIN enzyme molecule non-protein, organic molecules temporarily or permanently to enzyme near active site many vitamins ●NAD (niacin; B3) ●FAD (riboflavin; B2) ●Coenzyme A

Because both directions of a reversible process cannot be ____, the regeneration of ATP from ADP and inorganic phosphate is necessarily ____ Since ATP formation from ADP and inorganic P is not ____free energy must _____provide the energy for the ____ process of making ATP. Plants also use . Thus, the ATP cycle is a Enzymes speed up metabolic reactions by A spontaneous chemical reaction occurs _____y, but it may occur so ___ that it is For example, sucrose to fructose to glucose is However, if we add a small amount of the enzyme ____ to the solution, then all the sucrose may be ____, How does the enzyme do this? An enzyme is a In this chapter, we are focusing on enzymes that are ____ (and some ___).) Without regulation by enzymes, ____ would become terribly ___ bc of Every chemical reaction between molecules involves both bond ___ and ____. For example, the hydrolysis of sucrose involves Changing one mol- ecule into another generally involves __the starting molecule into a This contortion can be compared to the ____ of a metal key ring when u The key ring is highly ____ in its opened form but returns to a __ state once the key is

downhill, endergonic spontane- ous, be spent to make it occur. Catabolic (exergonic) pathways, especially cellular respiration, endergonic light energy to produce ATP revolving door through which energy passes during its transfer from catabolic to anabolic pathways lowering energy barriers without any requirement for outside energy, slowly that it is imperceptible. even though the hydrolysis of sucrose (table sugar) to glucose and fructose is exergonic, occurring spontaneously with a release of free energy (AG-7 kcal/mol), a solution of sucrose dissolved in sterile water will sit for years at room temperature with no appreciable hydrolysis. sucrase, hydrolyzed within seconds macromolecule that acts as a catalyst, a chemical agent that speeds up a reaction without being consumed by the reaction. proteins. (Some RNA molecules, called ribozymes, can function as enzymes) chemical traffic through the pathways of metabolism would become terribly congested because many chemical reactions would take such a long time breaking and bond forming breaking the bond between glucose and fructose and one of the bonds of a water molecule and then forming two new bonds, contorting the starting molecule into a highly unstable state before the reaction can proceed. bending of a metal key ring when you pry it open to add a new key. unstable stable threaded all the way onto the ring

If energy can't be destroyed, why can organisms jut use their energy over and over again? A system can put thermal energy to work only when If temperature is uniform, as it is in ____, A logical consequence of loss of useable energy as heat to the surroundings is that each energy transfer In many cases, increased entropy is evident in the Much of increasing entropy of universe is less As you convert chemical to kinetic energy such as w the bear, Entropy helps us understand ehy If a given process by itself leads to increase in entropy, the process

during every energy transfer or transformation, some energy converted to thermal energy and LOST AS HEAT , becoming unable to do work.(ex brown bear ..most chemical energy eat that will convert to KE is lost as heat) there is a temp diff that results in the thermal energy flowing as heat from from warmer location to a cooler one. as it is in a living cell, then heat generated during the chem reaction will simply warm a body of matter such as the organism makes universe more and more disordered.(aka entropy, randomness..more randomness,more entropy) physical disintegration of a systems organized structure. obvious ..bc takes form of increasing amounts of heat and less ordered forms of matter also increase disorder of surroundings by producing heat and small molecules such as CO2 it exhales tht are breakdown products of food. certain processes are energetically favorable and occur on own. can proceed without an input of energy!! spontaneous!!

product- active site —-Properties of enzymes—- They are reaction____- each enzyme only types of bonds? Not —— in reaction ●single enzyme molecule can ●enzymes ——- by the reaction Affected by ●any condition that affects ●____,____,____ Enzymes named for ●sucrase ●proteases ●lipases ●DNA polymerase ●pepsin

end result of reaction enzyme's catalytic site; substrate fits into active site ●Reaction specific- each enzyme works with a specific substrate (bc chemical fit between active site & substrate) ●H bonds & ionic bonds consumed catalyze thousands or more reactions per second unaffected cellular conditions protein structure temperature, pH, salinity reaction they catalyze breaks down sucrose break down proteins break down lipids builds DNA- adds nucleotides to DNA strand breaks down proteins (polypeptides)

Free energy eqn The equation describes the change in ____ of a system when accounting for the ____and change in ____) of the system. Entropy refers to the amount of ____ in a system. When placed in the context of energy exchange, entropy refers to energy that is What do we use energy for?

energy in system available to do work delta G= deltaH-TdeltaS free energy of a system when accounting for the transfer of heat (enthalpy) and change in disorder (entropy) of the system. disorder, unavailable for use grow reproduce organize

Reactions in an isolated system eventually reach ____ and can then The chemical reactions of metabolism are ____, and they, too, would reach _____ if they occurred in Because systems at equilibrium are at a ____ of G and ____, a cell that has reached metabolic equilibrium ⭐️ The fact that metabolism as a whole is ______ is one of the defining features of life. Like most systems, a living cell is not The constant ___of ____ in and out of ____ keeps the metabolic pathways from ____ and the cell continues to. A catabolic pathway in a cell does what in what??? An example is ______. Some of the ____ reactions of respiration are constantly "_____-that is, _____ The key to maintaining this lack of equilibrium is that The overall ___of____s is kept going by the huge As long as our cells have a steady ___ of ____and are able to _____ to the surroundings, their metabolic pathways never ____ and can We see once again how important it is to think of organ- isms as Sunlight provides a sAnimals and other nonphotosynthetic organisms in an ecosystem must have a source of ____ in the form of the ____ from ____ ATP powers ____ by A cell does three main kinds of work: Chemical work, the Transport work, the pumping of Mechanical work, A key feature in the way cells manage their energy resources to do this work is ____, the use of an

equilibrium, do no work reversible equilibrium the isolation of a test tube. minimum of G and can do no work is dead never at equilibrium not in equilibrium flow of materials in and out of the cell keeps the metabolic pathways from ever reaching equilibrium, do work throughout its life releases free energy in a series of reactions. cellular respiration re- versible, pulled" in one direction-that is, they are kept out of equilibrium. the product of a re- action does not accumulate but instead becomes a reactant in the next step; finally, waste products are expelled from the cell. sequence of reactions huge free-energy difference between glucose and oxygen at the top of the energy "hill" and carbon dioxide and water at the "down hill" end. steady supply of glucose or other fuels and oxygen , expel waste products, never reach equi- librium and can continue to do the work of life. open systems daily source of free energy for an ecosystem's plants and other photosynthetic organism free energy in the form of the organic products of photosynthesis cellular work by coupling exergonic reactions to endergonic reactions chemical, transport, mechanical pushing of endergonic reactions that would not occur spontaneously, such as the synthesis of polymers from monomers substances across mem branes against the direction of spontaneous movement Mechanical work, such as the beating of cilia), the contraction of muscle cells, and the movement of chromosomes during cellular reproduction energy coupling-exergonic process to drive an endergonic one

Based on their free-energy changes, chemical reactions can be classified as either An exergonic reaction proceeds witha Because the _____,, AG is ____ for an exergonic reaction Using AG as a standard for spontaneity, exergonic reactions are those that The magnitude of AG for an exergonic reaction represents the The greater the ___ in the _____,, the greater the Consider the overall reaction for cellular respiration : c6h12o6+6o2—>6co2+6H20 delta G= -686 kcal explain It is important to realize that the breaking of bonds The phrase "energy stored in bonds" is shorthand for the An endergonic reaction is one that Because this kind of reac- tion essentially stores _____, AG is ____. Such reactions are _____, and the magnitude of AG is the ______n. If a chemical process is exergonic, then A reversible process cannot be . EXPLAIN CELL RESP EX How, then, do plants make the sugar that organisms use for energy? Plants get the required energy-from

exergonic "energy outward") or endergonic (energy inward"). net release of free energy chemical mixture loses free energy (G decreases), negative occur spontaneously. maximum amount of work the reaction can perform (some of the free energy is re- leased as heat and cannot do work). greater the decrease in free energy, amount of work that can be done. 686kcal of energy are made available for work for each mole of glucose broken down by respiration under standard conditions. Because energy must be conserved, the products of respiration store 686 kcal less free energy per mole than the reactants. The products are the "exhaust" of a process that tapped the free energy stored in the bonds of the sugar molecules. does not release energy; on the contrary, as you will soon see, it requires energy. potential energy that can be released when new bonds are formed after the original bonds break, as long as the products are of lower free energy than the reactants. absorbs free energy from its surroundings, free energy in molecules (G increases) positive nonspontaneous quantity of energy required to drive the reactio (downhill), releasing energy in one direction, then the reverse process must be endergonic (uphill), using energy. downhill in both directions if AG = -686 kcal/mol for res piration, which converts glucose and oxygen to carbon dioxide and water, then the reverse process-the conversion of carbon dioxide and water to glucose and oxygen-must be strongly endergonic, with AG= +686 kcal/mol. Such a reaction would never happen by itself. 686 kcal to make a mole of glucose-from the environment by capturing light and converting its energy to chemical energy. Next, in a long series of exergonic steps, they gradually spend that chemical energy to assemble glucose molecules.

The _____of a reaction tells us whether or not the reaction occurs spontaneously The laws of thermodynamics that we've just discussed apply to the Recall that the universe is really equivalent to " Willard Gibbs, a professor at Yale, defined a very useful function called the Free energy is the Biologists find it most informative to focus on the ____ in free energy (___) during the DeltaG represents Centuries of experiments show that only reactions w a _____ can _____, so value if delta G tells is This principle is very important in the study of ____, where a major goal is to determine which _____and can be For a reaction to have a negative deltaG, the Because it has less free energy, the system in We can think of free energy as a meassure of a ___-it's tendency to Unstable systems tend to change in such a way that

free-energy change universe as a whole. the system plus the surroundings Gibbs free energy of a system (without considering its surroundings), symbolized by the letter G. portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell. change in free energy (delta G) during the chemical reactions of life. (DG=DGfinal-DGinitial) the difference between the free energy of the final state and the free energy of the initial state negative delta G can occur w no input of energy, so value of delta g tells us whether a particular reaction is a spontaneous one. metabolism, reactions occur spontaneously and can be harnessed to supply energy for cellular work system must lose free energy during the change from initial state to final state its final state is less likely to change and is therefore more stable than it was previously. sys tem's instability-its tendency to change to a more stable state (higher G) tend to change in such a way that they become more stable (lower G),

●Breaking down large molecules requires an ●this is called ●large biomolecules are ●must ●Activation energy—- ●moves the reaction

initial input of energy activation energy stable absorb energy to break bonds amount of energy needed to destabilize the bonds of a molecule over energy barrier

digesting more molecules = building polymers= An exergonic reaction ●Proceeds with a An endergonic reaction ●Is one that Endergonic vs. exergonic reactions ●Organisms require ___ to live ●where does that energy come from? If reactions are "downhill", why don't they just happen spontaneously? ●because

less organization=lower energy state more organization higher energy sate net release of free energy and is spontaneous absorbs free energy from its surroundings and is nonspontaneous exergonic (-delta G) - energy released - digestion vs endergonic (positive delta G) -energy invested -synthesis energy comes from coupling exergonic reactions (releasing energy) with endergonic reactions (needing energy) covalent bonds are stable bonds

___ and ____ model —-explain Induced fit model -More ____model -explain ... How work? Variety of mechanisms to 1.) synthesis ●active site orients ●enzyme brings 2.)digestion ●active site binds —-and puts stress on Factors that affect Enzyme function (7)

lock and key ... substrate fits into 3-D structure of enzyme' active site ●H bonds between substrate & enzyme ●like "key fits into lock" accurate model of enzyme action ●3-D structure of enzyme fits substrate ●substrate binding cause enzyme to change shape leading to a tighter fit ●"conformational change" ●bring chemical groups in position to catalyze reaction lower activation energy & speed up reaction substrates in correct position for reaction substrate closer together substrate & puts stress on bonds that must be broken, making it easier to separate molecules ●Enzyme concentration ●Substrate concentration ●Temperature ●pH ●Salinity ●Activators ●Inhibitors

Metabolic pathways.... -Chemical reactions of life are organized in ●divide chemical reaction into -artifact of - -intermediate ●control = EFFICIENCY-what is it? -Organized -enzymes are ●Link _____and _____! —-Feedback inhibition—- regulation and -product is used by -final product is -allosteric ____ of -___inhibition!! No unnecessary EX OF FEEDBACK INHIBITION

pathways many small steps evolution -efficiency branching points regulation groups of enzymes embedded in membrane and arranged sequentially endergonic and exergonic!! & coordination of production ●product is used by next step in pathway ● inhibitor of earlier step ●allosteric inhibitor of earlier enzyme ●feedback inhibition ●no unnecessary accumulation of product synthesis of amino acid, isoleucine from amino acid, threonine ●isoleucine becomes the allosteric inhibitor of the first step in the pathway ●as product accumulates it collides with enzyme more often than substrate does

Irreversible inhibition- Inhibitor -competitor..... -allosteric.. ●permanently ●permanently changes —-of—— ●exs? -cholinesterase inhibitors doesn't Allosteric Regulation-____changes by -inhibitors-keeps -activators-keeps Active form is stabilized by Inactive form is stabilized by

permanently binds to enzyme permanently binds to active site permanently binds to allosteric site ●permanently changes shape of enzyme ●nerve gas, sarin, many insecticides (malathion, parathion...) breakdown the neurotransmitter, acetylcholine Conformational changes by regulatory molecules ●keeps enzyme in inactive form ●keeps enzyme in active form allosteric activator molecule an allosteric inhibitor molecule

most enzymes are ___ and they are A permanent change in a gene, known as a —-, can result in a protein with In the case of an enzyme, if the changed amino acids are in the __ or some other ___ region, the____ may have a Under environmental conditions where the ____ _____ the organism, natural selection would tend to _____ causing it to This simplified model is generally accepted as the main way in which Regulation of enzyme activity helps Chemical chaos would result if all Intrinsic to life's processes is a cell's ability to tightly _____ by controlling ___ and ___ it's various enzymes It does this either by _____ on and off ___ or by In many cases, the molecules that naturally ____ in a cell behave something like _____ These regulatory molecules change ____ and the %___ of its ____ by binding to a ____, via Allosteric regulation is the term used to describe any case in which a . It may result in either ___ or ____ of Most enzymes known to be allosterically regulated are con structed from ___ or more ____, each composed of a ____ with its own The entire complex oscillates between in the simplest kind of allosteric regulation, an ___ or ___ regulatory molecule binds to a ____(sometimes called an ____), often located where ____. The binding of an activator to a regulatory site ___ the shape that has ___, whereas the binding of an ___ ___ the ___ .

proteins, and proteins are encoded by genes. mutation, one or more changed amino acids. in the active site or some other crucial region, the altered enzyme might have a novel activity or might bind to a different substrate. new function benefits the organis, tend to favor the mutated form of the gene, causing it to persist in the population the multitude of different enzymes arose over the past few billion years of life's history control metabolism all of a cell's metabolic pathways were operating simultaneously. regulate its metabolic pathways, when and where its various enzymes are active. switching on and off the genes that encode specific enzymes or, as we discuss here, by regulating the activity of enzymes once they are made. regulate enzyme activity, reversible noncompeti tive inhibitors an enzyme's shape and the functioning of its active site, site elsewhere on the molecule, via non covalent interactions. protein's function at one site is affected by the binding of a regulatory molecule to a sepa- rate site inhibition or stimulation of an enzyme's activity two or more subunits, each composed of a polypeptide chain with its own active site. two different shapes, one catalytically ac- tive and the other inactive activating or inhibiting regulatory molecule binds to a regulatory site (sometimes called an al losteric site), often located where subunits join. stabilizes the shape that has functional active sites, whereas the binding of an inhibi- tor stabilizes the inactive form of the enzyme

Note that as we're using it here, the word spontaneous does not imply that the process would occur _____; rather, the word signifies that it is Some spontaneous processes, such as an explosion, may be ______s, while others, such as the rusting of an old car over time, are A process that, on its own, leads to a decrease in entropy is said to be ____. it will happen only if ex of water w its spontaneous and nonspon movements This understanding gives us another way to state the second law: For a process to occur spontaneously, it Living systems ____ the entropy of their surroundings, as It is true that cells create _____ from less _____ For example, simpler molecules are ____ into the more ____ and_____. are ordered into _____. At the organismal level as well, complex and beautifully ordered structures result from On the other hand, an organism also takes in _____ from the surroundings and replaces them w For example, an animal obtains As ____ pathways ____ these molecules , the animal releases ___ and ___- small molecules tht contain The depletion of chemical energy is accounted for by On a larger scale, energy flows into most ecosystems in form of ___ and exit as __

quickly, energetically favorable. (In fact, it may be helpful for you to think of the phrase "energetically fa vorable" when you read the formal term "spontaneous.") virtually instantaneous, much slower nonspontaneous: It will happen only if energy is supplied. For instance, we know that water flows downhill spontaneously but moves uphill only with an input of energy, such as when a machine pumps the water against gravity. must increase the entropy of the universe. increase, pre- dicted by thermodynamic law. ordered structures, organized starting materials. ordered into the more complex structure of an amino acid, and amino acids are ordered into polypeptide chains biological processes that use sim pler starting materials (Fiqure 6.4), organized forms of matter and energy from the surroundings and replaces them with less ordered forms. starch, proteins, and other complex molecules from the food it eats. catabolic, break these molecules down carbon dioxide and water- small molecules that possess less chemical energy than the food did. heat generated during metabolism light, exit as heat.

Compounds which regulate enzymes Inhibitors ●molecules that ●4 types inhibition Competitive Inhibitor ●Inhibitor & substrate "___" for ●EX -EX 2 (bothimportsnt) ●Overcome by ●saturate solution with ____ so that it Competitive inhibitor interferes with Non-Competitive Inhibitor ●Inhibitor binds to ●allosteric inhibitor binds to. Caused enzyme to ____change- ●some anti-cancer drugs inhibit ●cyanide poisoning irreversible _____ stops production of Non competitive inhibition

reduce enzyme activity competitive inhibition ●noncompetitive inhibition ●irreversible inhibition ●feedback inhibition compete" for active site -penicillin blocks enzyme bacteria use to build cell walls disulfiram (Antabuse) treats chronic alcoholism ●blocks enzyme that breaks down alcohol ●severe hangover & vomiting 5-10 minutes after drinking increasing substrate concentration substrate so it out-competes inhibitor for active site on enzyme active site of enzyme so substrate can't bind site other than active site allosteric site.. change shape ( conformational change-active site is no longer functional binding site.. ...keeps enzyme inactive enzymes involved in DNA synthesis ●stop DNA production, stop division of more cancer cells irreversible inhibitor of Cytochrome C, an enzyme in cellular respiration ●stops production of ATP Allosteric inhibitor changes shape of enzyme so can't bind to substrate

In an exergonic reaction, energy is

released to the surroundings. The bonds being formed are stronger than the bonds being broken. In an endergonic reaction, energy is absorbed from the surroundings. The bonds being formed are weaker than the bonds being broken.

The subunits of an allosteric enzyme fit together in such a way that a Through this interaction of subunits, a single __or___ molecule that binds to one regulatory site will ___ of . Fluctuating ____ of regulators can cause a The products of ATP hydrolysis (ADP and inorganic phosphate for example), play a complex role in balancing the . ATP binds to several _____, lowering their ___ for ___ and thus . ADP, however, functions as an . This is logical because ___ functions in If ATP production lags behind its use, ADP ____ and ___ then___ that___, producing. If the supply of ATP exceeds demand, then . ATP, ADP, and other related molecules also affect key enzymes in . In this way, allosteric enzymes control the In another kind of allosteric activation, a substrate mol ecule binding to one active site in a multisubunit enzyme triggers a__ thereby ). Called ____, this mechanism amplifies the ___ of ___ to : One substrate molecule primes an Cooperativity is considered allosteric regulation because Although hemoglobin is not an enzyme (it carries __rather than...), classic studies of hemoglobin have elucidated the principle of —- . Hemoglobin is made up of ___, each w The binding of an oxygen molecule to one binding site ___ the affinity Thus, where oxygen is at ____s, such as in the lungs or gills, hemoglobin's In oxygen-deprived tissues, how- ever, the release of each oxygen molecule ____ the ___, resulting in Cooperativity works similarly in ____s that have been studied. . Earlier, we discussed the___ of an This is a common mode of ____, called ____ in which a metabolic pathway is . Some cells use this five-step path- way to synthesize the

shape change in one subunit is transmitted to all others. activator or inhibitor affect the active sites of all subunits concentrations, sophis- ticated pattern of response in the activity of cellular enzymes. balancing the flow of traffic between an- abolic and catabolic pathways by their effects onkey enzymes catabolic enzymes allosterically affinity for substrate and thus inhibiting their activity activator of the same enzymes catabolism, regenerating ATP accumulates and activates the enzymes that speed up catabolism, more ATP catabo- lism slows down as ATP molecules accumulate and bind to the same enzymes, inhibiting them anabolic pathways rates of important reactions in both sorts of metabolic pathways. shape change in all the subunits, thereby increas- ing catalytic activity at the other active sites cooperativity, response of enzymes to substrates enzyme to act on additional substrate molecules more read ily (binding of substrate molecule to active site of one subunit locks all subunits in active conformation) binding of the substrate to one active site affects catalysis in another active site O2 rather than catalyzing a reaction, cooperativity four subunits, each with an oxygen-binding site increases the affinity for oxygen of the remaining binding sites. high levels, affinity for oxygen increases as more binding sites are filled. decreases the oxygen affinity of the other binding sites, resulting in the release of oxygen where it is most needed. multisubunit enzymes allosteric inhibition of an enzyme in an atp generating pathway by ATP itself. metabolic control feedback inhibition, halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway. amino acid isoleucine from threonine, another aminio

ATP hydrolysis causes changes in the ___ and ____ of This can occur either (a) ____, by _____, as shown for a ____ carrying out ____, or (b) ____, via ____binding of, as is the case for or can occur ____via The key to coupling exer- gonic and endergonic reactions is the formstion of _____, which is more ___ than the .Transport and mechanical work in the cell are also nearly always ___ by _____. In these cases, ATP hydrolysis leads to a ____ in a ___ and most often . Sometimes this occurs via a ______ as seen for the transport pro- tein in Fiqure 6.10a, In most instances of mechanical work involving motor proteins "walking" along cytoskeletal elements, a cycle occurs in which first....second...next.... . At each stage, the motor protein ______n, resulting in ___ a,omg the ____. . Phosphorylation and dephosphor ylation also promote crucial An organism at work uses _____, but ATP is a ____ resource that can be ___ by the addition of The free energy required to phosphorylate ADP comes from This shuttling of ___ and ____y is called the ____, and it couples ___ to ____ . If ATP could not be regenerated by the phosphorylation of ADP, humans would use up nearly their

shapes and binding affinities of proteins. directly, phosphorylation, membrane protein carrying out active transport of a solute indirectly, noncovalent binding of ATP and its hydrolytic products, motor proteins that move vesicles (and other organelles) along cytoskeletal "tracks" in the cell formation of this phosphorylated intermediate, reactive (less stable) than the original unphosphorylated molecule powered by the hydrolysis of ATP change in a protein's shape and often its ability to bind another molecule phosphorylated intermediate, ATP is first bound noncovalently to the motor protein. Next, ATP is hydrolyzed releasing ADP and inorganic phosphate , Another ATP molecule can then bind changes its shape and ability to bind the cytoskeleton movement of the protein along the cytoskeletal track protein shape changes during cll signaling ATP continuously, renewable regenerated by the addition of phosphate to ADP exergonic breakdown reactions (catabolism) in the cell. inorganic phosphate and energy, ATP cycle cell's energy-yielding (exergonic) processes to the energy- consuming (endergonic) ones. body weight in ATP each day.

As isoleucine accumulates, it ____ts own synthesis by Feedback inhibition thereby prevents the cell from making _____, and thus l The cell is not just a bag of chemicals with thousands of differ- ent kinds of enzymes and substrates in a random mix. The cell is ___, and cellular structures . In some cases, a team of ____ for ___ is assembled into a . The arrangement facilitates the __of___, with the product from the ____becoming the Some enzymes and en- zyme complexes have ____ within the cell and act as structural s. Others are in ___ within particular membrane-____ each eith it's own . For example, in eukaryotic cells, the enzymes for cellular respiration reside in In this chapter, you have learned that metabolism, the _____e, is a choreographed interplay of . In the next chapter, we'll explore cellular respi- ration, the major ___ that

slows down, allosterically inhibiting the enzyme for the first step of the pathway. more isoleucine than is necessary wasting chemical resources. compartmentalized, and cellular structures help bring order to metabolic pathways enzymes for several steps of a metabolic pathway is assembled into a mul tienzyme complex sequence of reactions, first enzyme , substrate for an adjacent enzyme in the complex, and so on, until the end product is released. fixed locationns, structural components of particular membrane solution, enclosed eukaryotic or- ganelles, each with its own internal chemical environment specific locations within mitochondria (Figure 6.20). in- tersecting set of chemical pathways characteristic of life, thousands of different kinds of cel- lular molecules catabolic pathway that breaks down organic molecules, releasing energy that can be used for the crucial processes of life

In most enzymatic reactions, the substrate is held in the active site by The ____s of a few of the amino acids that make up the active site ____ the conversion of ____t, and the product ___ from the ___. The enzyme is then free to .Enzymes, like other catalysts, emerge from the reaction in Therefore, very ___ amounts of enzyme can have a huge ____t by functioning Most metabolic reactions are ___, and an enzyme can ___, depending on which This in turn depends mainly on the relative _____ of____ The net effect is always in the Enzymes use a variety of mechanisms that ___ and ___ a reaction. First, in reactions involving two or more reactants, the active site provides Second, as the active site of an enzyme ___te bound ___, the enzyme may ____ molecules toward their _____form, stressing and _____ that must be Because EA is proportional to the ______ of ____s, distorting the substrate helps it____ and thus reduces the amount of ___ that must be Third, the active site may also provide a ____ that is more ____ to a reaction than For ex- ample, if the active site has amino acids with acidic R groups, the active site In such cases, an acidic amino acid may facilitate___ to the A fourth mechanism of catalysis is the ____ of the ____ in the chemical reaction. Sometimes this process even involves brief ___ between the ____ and ____ of the

so-called weak interactions, such as hydrogen bonds and ionic bonds. R group, catalyze the conversion of substrate to product, and the product departs from the active site take another substrate molecule into its active site their original form. small, metabolic impact over and over again in catalytic cycles. reversible, catalyze either the forward or the reverse reaction, depending on which direction has a negative AG concentrations of reactants and prod- ucts. direction of equilibrium lower activation energy and speed up a reaction provides a template on which the substrates can come together in the proper orienta- tion for a reaction to occur between them clutches the bound substrates, the enzyme may stretch the substrate molecules toward their transition state form, stressing and bending critical chemical bonds that must be broken during the reaction difficulty of breaking the bonds, approach the transition state and thus reduces the amount of free energy that must be absorbed to achieve that state. microenviron- ment that is more conducive to a particular type of reaction than the solution itself would be without the enzyme. may be a pocket of low pH in an otherwise neutral cell. H transfer to the substrate as a key step in catalyzing the reaction direct participa- tion, active site covalent bonding between the substrate and the side chain of an amino acid of the enzyme.

Also, enzymes are very ____ for the reactions they ____, so they determine which Substrate The enzyme binds to ____forming a . While enzyme and substrate are joined, the ___ of the enzyme converts The overall process can be summarized as follows: For example, the enzyme sucrase The reaction catalyzed by each enzyme is very ___- an enzyme can . For instance, sucrase will act ___ on ___, and not . What accounts for this molecular recognition? Recall that most enzymes are _____, and they r are macromolecules with ____s. The specificity of an enzyme results from ____ which is a consequence of its Only a restricted region of the enzyme molecule actually This region, known as the ____, is typically a ____ or ____ Usually, the active site is formed by only _____s, with the rest of the ____molecule providing a____ tht determines the . The specificity of an enzyme is attributed to a ____ between the shape of ___ and An enzyme is NOT a ___ structure ___ into a ____ . In fact, recent work by biochemists has shown that enzymes (and other proteins) seem to "__" between subtly The shape that best fits the substrate isn't nec- essarily the one with the ____, but during the very short time the enzyme takes on this shape, its___ can The active site itself is also not a _____for the substrate. As the substrate enters the active site, the enzyme ____ slightly due to ___ between the substrate's ___ and the ____ This ____e makes the active site ____). This tightening of ____- called____- is Induced fit brings ___ of the active site to

specific, catalyze which chemical processes will be going on in the cell at any given time. The reactant an enzyme acts on its substrate (or substrates when there are two or more reactants), forming an enzyme- substrate complex catalytic action of the enzyme converts the substrate to the product (or products) of the reaction enzyme plus substrate, enzyme substrate complex, enzyme and products most enzyme names end in -ase) catalyzes the hydrolysis of the disaccharide sucrose into its two monosaccharides, glucose and fructose specific; an en- zyme can recognize its specific substrate even among closely related compounds only on sucrose and will not bind to other disaccharides, such as malt- ose proteins, unique three-dimensional configuration its shape, which is a consequence of its amino acid sequence binds to the substrate active site pocket or groove on the surface of the enzyme where catalysis occurs a few of the enzyme's amino acid protein molecule providing a framework that determines the shape of the active site complementary fit between the shape of its active site and the shape of the substrate, like that seen in the binding of a signaling molecule to a receptor protein stiff, locked into a given shape dance" between subtly different shapes in a dynamic equilibrium, with slight differ ences in free energy for each "pose lowest energy active site can bind to the substrate. rigid receptacle changes shape slightly due to inter- actions between the substrate's chemical groups and chemical groups on the side chains of the amino acids that form the ac- tive site. shape change fit even more snugly around the substrate the binding after initial contact-called induced fit-is like a clasping handshake. Induced fit brings chemical groups of the active site into positions that enhance their ability to catalyze the chemical reaction.

Subsequent steps of the reaction restore _____ so that the . The rate at which a particular amount of enzyme converts substrate to product is partly a function ______-: The more _____are available, the more _____they access However, there is a limit to how —- the reaction can be _____ At some point, the concentration of substrate will be ____ enough that all enzymes will As soon as the product exits a active site, . At this substrate concentration, the enzyme is said to be ____, and the rate of the ____ is determined by . When an enzyme population is saturated, the only way to increase the rate of product formation is _____ Cells often increase the rate of a reaction by The activity of an enzyme-how ___ it ____, is affected by It can also be affected by chemicals that —- the enzyme The ___ of proteins are ___ to their ____t As a consequence, each enzyme works —-- under some ____ than ____, because these _____conditions favor ____ . ___ and ____are environmental factors important in the activity of an enzyme. Up to a point, the rate of an en- zymatic reaction ____, partly bc ____ collide w Above that temperature however, STAR STAR ⭐️ WHY????? . Each enzyme has an ____ at which it's reaction rate Without ____ the enzyme, this temperature allows the ——-f molecular —— and the fastest _____ of the ___to____ molecules. Most human enzymes have optimal temperatures of about The thermophilic bacteria that live in hot springs contain Just as each enzyme has an optimal temperature, it also has a The optimal pH values for most enzymes fall in the range of —-, but there are excep- tions. for- example, pepsin, a ____, works best at —.

the side chains to their original states so the active sight is the same after the reaction as it was before. . initial concentra- tion of the substrate: The more substrate molecules that are available, the more frequently they access the active sites of the enzyme molecules fast the reaction can be pushed by adding more substrate to a fixed concentration of enzyme high enough that all enzyme molecules will have their active sites engaged another substrate molecule enters saturated, reaction is determined by the speed at which the active site converts substrate to product to add more enzyme producing more enzyme molecules. efficiently the enzyme functions-is affected by general environmental factors, such as temperature and pH. specifically influence that enzyme. three-dimensional structures sensitive to their environment works better under some conditions than under other conditions, because these optimal conditions favor the most active shape for the enzym Temperature and pH increases with increasing temperature, partly because substrates collide with active sites more frequently when the molecules move rapidly. the speed of the enzymatic reaction drops sharply The thermal agitation of the enzyme molecule disrupts the hydrogen bonds, ionic bonds, and other weak interactions that stabilize the active shape of the enzyme, and the molecule eventually denatures optimal temperature at which its reaction rate is greatest. denaturing, the greatest number of molecular collisions and the fastest conversion of the reactants to product molecules. 35-40°C (close to human body temperature) enzymes with optimal temperatures of 70°C or higher pH at which it is most active pH 6-8 digestive enzyme in the human stomach, pH 2

Metabolism Metabolism is an —- property of In a metabolic pathway, a specific molecule is Each step of the pathway is mechanisms that regulate enzymes balance Metabolism as a whole managed the ___ and ____of the cell Catabolic pathways (____ pathways) A major pathway of catabolism is Energy stored in the ___ becomes available Anabolic pathways Exs of anabolism Catabolic and anabolic pathways are the "____" and "_____" avenues of the metabolic landscape Energy released from the ___ of ____

totality of an organisms chemical reactions émergent property of life that arises from interaction btwn molecules altered in a series of defined steps , resulting in a product catalyzed by a specific enzyme (starting molecules goes thru enzyme one, two, three, having reaction thru each, till get to final product) metabolic supply and demand material and energy resources (breakdown) metabolic pathway that releases energy by breaking down complex molecules to form simpler compounds... cellular respiration-sugar glucose and other organic fuels are broken down in the presence of oxygen to CO2 and water organic molecules becomes available to do the work of the cell such as vilify beating or membrane transport. consume energy to build complicated molecules from simpler ones...they're sometimes called biosynthetic pathways synthesis of amino acid from smaller molecules and synthesis of protein from amino acids. uphill and downhill downhill reactions of catabolic pathways can be stored and then used to drive uphill reactions of anabolic pathways

how is energy converted from one form to another? ex Chemical energy itself is derived from thermodynamics system vs surroundings An isolated system is unable to Organisms are ___ systems They ansorb _____ and first law By converting ___ to ____, plants second -

young woman climbing ladder to diving platform is releasing chemical energy from food she ate for lunch and using some of that energy to form work of climbing. KE of muscle movement is this being transformed into potential due to her increasing heigh above water. Young man diving is concerting his potential energy in to KE, which is then transferred to the water as he enters it . small amount of energy lost as heat. light energy absorbed by plants during photosynthesis. ....orgs r energy transformers study of energy transformations that occur in a collection of matter. system-matter under study and everything else in universe is surroundings exchange either energy or matter with surroundings outside the system ....but in open system, energy and matter can be transferred btwn system and surroundings open energy (light energy or chem energy from food) and release heat and metabolic waste products (ex co2) to surroundings energy of universe is constant... energy can be transferred or stored but can't be created or destroyed (aka law of conservation of energy) sunlight to chem energy, plant acts as energy transformer not energy producer every energy transfer or transformation increases entropy of universe .

cooperativity -substrate acts as -substrate causes ___in -___fit -favors binding of -makes enzymes more ex- HEMOGLOBIN -___peptide chains -can bind -1sr ____ -now, ____ for other

●Substrate acts as an activator ●substrate causes conformational change in enzyme ●induced fit ●favors binding of substrate at 2nd site ●makes enzyme more active & effective ●hemoglobin 4 polypeptide chains ●can bind 4 O2; ●1st O2 binds ●now easier for other 3 O2 to bind