General College Biology I, Chapter 8, Metabolism: Energy and Enzymes
Vocabulary: metabolism, metabolic pathway, catabolic pathway, anabolic pathway, chemical energy, potential energy, kinetic energy, heat, thermodynamics, entropy, endergonic, exergonic, activation energy, phosphorylation, enzyme, catalyst, substrate, active site, allosteric site, cofactor, coenzyme, competitive inhibitor, noncompetitive inhibitor, allosteric regulation, feedback inhibition
Objectives: After attending lectures and studying the chapter, the student should be able to:
1. Define metabolism.
2. Describe a metabolic (biochemical) pathway and distinguish between anabolic pathways
and catabolic pathways.
3. Explain the role of energy and enzymes in the chemical reactions in the cells of living
things.
4. Define energy.
5. List and describe 5 forms of energy.
6. State the 1st and 2nd Laws of Thermodynamics and relate each to living systems.
7. Distinguish between endergonic and exergonic chemical reactions.
8. Describe the activation energy of a chemical reaction.
9. Describe ATP and its role as a source of chemical energy in cells.
10. Write the general chemical reactions for making ATP and using ATP.
11. State the function of enzymes.
12. Define catalyst and state why an enzyme is a catalyst.
13. Define and describe active site and relate it to the function of enzymes.
14. Relate the shape of enzymes to their function.
15. Define denaturation of proteins and explain how less than optimum temperature and pH
conditions could affect the function of enzymes
16. State the two types of cofactors (and examples of each), and describe their role in the function of some enzymes.
17. Describe the allosteric site found in some enzymes and explain how allosteric effectors (activators or inhibitors) influence the function of some enzymes.
18. Distinguish between competitive and noncompetitive inhibitors.
19. Describe feedback inhibition related to a metabolic pathway
Terms : Hide Images
| 1794698097 | Concept 8.1: An organism's metabolism transforms matter and energy, subject to the laws of thermodynamics | ... | 0 | |
| 1794698137 | Metabolism | The totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism |  | 1 |
| 1794698138 | Metabolic pathway | A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule to simpler molecules (catabolic pathway) |  | 2 |
| 1794698139 | Catabolic pathway | Releases Energy. A metabolic pathway that releases energy by breaking down complex molecules to simpler molecules |  | 3 |
| 1794698140 | Anabolic pathway | Consumes Energy. A metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules |  | 4 |
| 1794698141 | Bioenergetics | Bioenergetics is the study of how organisms manage their energy resources |  | 5 |
| 1794698142 | Energy | The capacity to cause change, especially to do work (to move matter against an opposing force). |  | 6 |
| 1794698143 | Kinetic energy | Energy of motion |  | 7 |
| 1794698144 | Heat (thermal) energy | Kinetic energy associated with random movement of atoms or molecules |  | 8 |
| 1794698145 | Potential energy | The energy that matter possesses as a result of its location or spatial arrangement (structure) |  | 9 |
| 1794698146 | Chemical energy | Energy available in molecules for release in a chemical reaction; a form of potential energy |  | 10 |
| 1794698147 | Thermodynamics | The study of energy transformations that occur in a collection of matter. |  | 11 |
| 1794698148 | First law of thermodynamics | The principle of conservation of energy; energy can be transferred and transformed, but it cannot be created or destroyed |  | 12 |
| 1794698149 | Entropy | a measure of disorder, or randomness |  | 13 |
| 1794698150 | Second law of thermodynamics | Energy transfer. The principle stating that every energy transfer or transformation increases the entropy of the universe. Usable forms of energy are at least partly converted to heat |  | 14 |
| 1794698151 | Spontaneous process | Without Energy. Spontaneous processes occur without energy input; they can happen quickly or slowly |  | 15 |
| 1794698152 | What is the second law of thermodynamics? | The principle stating that every energy transfer or transformation increases the entropy of the universe. |  | 16 |
| 1794698153 | What is the first law of thermodynamics? | Energy can be transferred and transformed, but it cannot be created or destroyed | | 17 |
| 1794698154 | How does the second law of thermodynamics help explain the diffusion of a substance across a membrane? | The second law is the trend toward randomization, or increasing entropy. When the concentration of a substance on both sides of a membrane are equal, the distribution is more random than when they are unequal. Diffusion of a substance to a region where it is initially less concentrated INCREASES ENTROPY, making it an energetically favorable (SPONTANEOUS) process. |  | 18 |
| 1794698155 | Describe the forms of energy found in an apple as it grows on a tree, then falls, then is digested by someone who eats it | Potential. Chemical. Kinetic. Thermal. As it sits on the tree, the apple has potential energy because of its position and chemical energy because of its nutrients. As it is falling it has kinetic energy. When eaten and digested, some chemical energy becomes work and the rest is heat. |  | 19 |
| 1794698098 | If you place a teaspoon of sugar in the bottom of a glass of water, it will dissolve completely over time. Left longer, crystals will reappear. Explain these observations in terms of entropy | Sugar crystals are less ordered - more entropy as they dissolve. As the water becomes less ordered - more entropy and evaporates, the sugar becomes more ordered- decrease in entropy, becoming crystals | 20 | |
| 1794698156 | Concept 8.2 The free energy change of a reaction tells us whether or not the reaction occurs spontaneously. | ... |  | 21 |
| 1794698157 | Free energy | The portion of a biological system's energy that can perform work when temperature and pressure are uniform throughout the system. The change in free energy of a system is calculated by the equation delta G = delta H - T delta S, where delta H is the change in enthalpy (in biological systems, equivalent to total energy), T is the absolute temperature, and delta S is the change in entropy. |  | 22 |
| 1794698158 | Exergonic reaction | Energy is released. A reaction is exergonic if more energy is released than supplied. delta G<0 |  | 23 |
| 1794698159 | Endergonic reaction | Energy must be supplied. A reaction is endergonic if more energy is supplied than is released. delta G>0 |  | 24 |
| 1794698160 | Endergonic reaction | The reaction will not occur spontaneously delta G>0 |  | 25 |
| 1794698161 | Cellular respiration uses glucose and oxygen, which have high levels of free energy, and releases CO2 and water, which have low levels of free energy. Is cellular respiration spontaneous or not? | Cellular Respiration is SPONTANEOUS! |  | 26 |
| 1794698162 | Cellular respiration uses glucose and oxygen, which have high levels of free energy, and releases CO2 and water, which have low levels of free energy. Is it exergonic or endergonic? | Cellular Respiration is an EXERGONIC process | | 27 |
| 1794698163 | Cellular respiration uses glucose and oxygen, which have high levels of free energy, and releases CO2 and water, which have low levels of free energy. What happens to the energy released from glucose? | The energy released from glucose is used to do work in the cell or is lost as heat | | 28 |
| 1794698164 | As we saw in figure 7.20 on page 137, a key process in metabolism is the transport of hydrogen ions (H+) across a membrane to create a concentration gradient. Other processes can result in an equal concentration of H+ on each side. Which situation allows the H+ to perform work on the system? | At equilibrium, the H+ concentration is the same and the Hydrogen ions can no no work. When there is an imbalance, or a gradient Hydrogen ions go to work. |  | 29 |
| 1794698165 | As we saw in figure 7.20 on page 137, a key process in metabolism is the transport of hydrogen ions (H+) across a membrane to create a concentration gradient. Other processes can result in an equal concentration of H+ on each side. Which situation allows the H+ to perform work on the system and how is the answer consistent with what is shown in regards to energy in figure 7.20? | Figure 7.20 shows that an energy input via ATP hydrolysis is required to establish a concentration gradient that allows the Hydrogen ions to go to work. | | 30 |
| 1794698166 | Glow in the dark necklaces start glowing once activated which usually involves snapping the necklaces in a way that allows two chemicals to react and emit light in the form of chemilluminescence. Is the chemical reaction exergonic or endergonic? | The reaction is EXERGONIC because it releases energy in the form of light. |  | 31 |
| 1794698167 | Concept 8.3 ATP powers cellular work by coupling exergonic reactions to endergonic reactions | ... |  | 32 |
| 1794698168 | Energy coupling | In cellular metabolism, the use of energy released from an exergonic reaction drives an endergonic reaction |  | 33 |
| 1794698169 | ATP | Adenosine Triphosphate |  | 34 |
| 1794698170 | ATP (adenosine triphosphate) | An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells. |  | 35 |
| 1794698171 | Phosphorylated intermediate | A molecule (often a reactant) with a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule |  | 36 |
| 1794698099 | What are the three main types of work that a cell does? | Chemical Transport Mechanical | 37 | |
| 1794698172 | How does ATP typically transfer energy from ergonic to endergonic reactions in the cell? | By Phosphorylating, adding phosphate groups to, other molecules. Exergonic process phosphorylate ADP to regenerate ATP |  | 38 |
| 1794698100 | Which of the following combinations has more free energy: Glutamic acid + ammnia +ATP or Glutamine + ADP + P1? Explain | A set of coupled reactions can transform the first combinations into the second. Since this is an exergonic process overall, Delta G is negative and the first combination must have more energy. | 39 | |
| 1794698173 | Considering what we learned in concepts 7.3 and 7.4 (pages 134-136), does figure 8.10a show passive or active transport? | Active Transport - the solute is being transported against its concentration gradient |  | 40 |
| 1794698174 | Concept 8.4 Enzymes Speed Up Metabolic Reactions by Lowering Energy Barriers | ... |  | 41 |
| 1794698175 | Enzyme | A macromolecule serving as a catalyst in a chemical agent that increases the rate of a reaction without being consumed by the reaction; most are proteins |  | 42 |
| 1794698176 | Catalyst | A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction |  | 43 |
| 1794698177 | Activation energy | The amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation |  | 44 |
| 1794698178 | Substrate | the reactant on which an enzyme works. |  | 45 |
| 1794698179 | Enzyme-substrate complex | a temporary complex formed when an enzyme binds to is substrate molecule(s). |  | 46 |
| 1794698180 | Active site | the specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs |  | 47 |
| 1794698181 | Induced fit | Caused by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snuggly to the substrate |  | 48 |
| 1794698182 | Cofactor | Any nonprotein molecule or ion that is required for the proper functioning of of an enzyme; can be permanently bound to the active site or may be loosely bound and reversibly, along with the substrate during catalysis. |  | 49 |
| 1794698183 | Coenzyme | an organic molecule serving as a cofactor; in metabolic reactions, most vitamins function as this. |  | 50 |
| 1794698184 | Competitive inhibitor | a substance that reduces the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics |  | 51 |
| 1794698185 | Noncompetitive inhibitor | a substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing an enzyme's shape so that the active site no longer effectively catalyses the conversion of substrate to product |  | 52 |
| 1794698101 | Many spontaneous reactions occur very slowly. Why don't all spontaneous reactions occur instantly? | While spontaneous reactions are exergonic, if they have a high activation energy that is rarely reached, the rate of reaction could be very slow | 53 | |
| 1794698102 | Why do enzymes act only on very specific substrates? | Only the specific substrate will fit properly into the active site of an enzyme where the catalysis happens | 54 | |
| 1794698103 | Malonate is an inhibitor of the enzyme succinate dehyrogenase. How would you determine whether malonate is a competitive or noncompetitive inhibitor? | With malonate present, increase the amount of the normal substrate and determine if the reaction increases, if it does, then you know that malonate is a competitive inhibitor | 55 | |
| 1794698104 | In nature, what conditions could lead to natural selection favoring bacteria with enzymes that could break down the fucose-containing disaccharide discussed above? | If lactose wasn't present in the environment as a source of food and the fucose-containing disaccharide was available, bacteria that could digest the latter would be better able to grow and multiply than those that could not. | 56 | |
| 1794698186 | Concept 8.5 Regulation of Enzyme Activity Helps Control Metabolism | ... | | 57 |
| 1794698187 | Allosteric regulation | The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site |  | 58 |
| 1794698188 | Cooperativity | A kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the other subunits, facilitating binding of additional substrate molecules to those subunits |  | 59 |
| 1794698189 | Feedback inhibition | A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway. |  | 60 |
| 1794698105 | How do an activator and an inhibitor have different effects on an allosterically regulated enzyme? | The activator binds and stabilizes he active form of an enzyme, whereas the inhibitor will stabilize the INACTIVE form | 61 | |
| 1794698106 | You want to design drug that inhibits a particular enzyme, after research you learn that an enzymes active site is simmilar to that of several other enzymes. What would be a good approach to develop your inhibitor drug? | An inhibitor that binds to the active site of the enzyme you want to inhibit could also bind to and block the enzymes with similar structures, causing significant side effects. For this reason you would be better off choosing to screen chemical compounds that bind allosterically to the enzyme in question because allosteric regulatory sites are less likely to share similarity with other enzymes. | 62 | |
| 1794698107 | Define Metabolism | The totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism | 63 | |
| 1794698108 | Define Energy | The capacity to cause change, especially to do work (to move matter against an opposing force). | 64 | |
| 1794698109 | List and describe 5 forms of energy | Kinetic Potential Chemical Heat/Thermal | 65 | |
| 1794698110 | What is a catalyst? | A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction. | 66 | |
| 1794698111 | Distinguish between anabolic and catabolic reactions? | Anabolic is building a molecule by consuming energy and catabolic is breaking it down to release energy | 67 | |
| 1794698112 | Word Roots: allo- | different (allosteric site: a specific receptor site on some part of an enzyme molecule remote from the active site) | 68 | |
| 1794698113 | Word Roots: ana- | up (anabolic pathway: a metabolic pathway that consumes energy to build complex molecules from simpler ones) | 69 | |
| 1794698114 | Word Roots: bio- | ife (bioenergetics: the study of how organisms manage their energy resources) | 70 | |
| 1794698115 | Word Roots: cata- | down (catabolic pathway: a metabolic pathway that releases energy by breaking down complex molecules into simpler ones) | 71 | |
| 1794698116 | Word Roots: endo- | within (endergonic reaction: a reaction that absorbs free energy from its surroundings) | 72 | |
| 1794698117 | Word Roots: ex- | out (exergonic reaction: a reaction that proceeds with a net release of free energy) | 73 | |
| 1794698118 | Word Roots: kinet- | movement (kinetic energy: the energy of motion) | 74 | |
| 1794698119 | Word Roots: therm- | heat (thermodynamics: the study of the energy transformations that occur in a collection of matter) | 75 | |
| 1794698120 | Metabolic pathway | A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule to simpler molecules (catabolic pathway). | 76 | |
| 1794698190 | Define how an enzyme works | An enzyme serves as a biological catalyst, increasing the rate of a reaction without being changed into a different molecule. An enzyme does not add energy to a reaction; instead, it speeds up a reaction by lowering the energy barrier. |  | 77 |
| 1794698121 | Molecule | Two or more atoms held together by covalent bonds. | 78 | |
| 1794698191 | Substrate | The reactant on which an enzyme works. | | 79 |
| 1794698122 | Name three factors that affect enzyme action | pH Temperature Substrate Concentration | 80 | |
| 1794698123 | What does it mean when an enzyme is denatured? | An enzyme is said to be denatured when it loses its functional shape. | 81 | |
| 1794698192 | What does Gibbs Free Energy Measure? | Chemical Energy |  | 82 |
| 1794698193 | Give the equation for Gibbs Free Energy | Delta G equals delta H - T delta S |  | 83 |
| 1794698124 | Explain the Gibbs Free Energy Equation | A change in free energy is equal to a change in heat content minus a change in Temperature times Randomness | 84 | |
| 1794698194 | The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of | allosteric regulation | | 85 |
| 1794698125 | What is meant by the "induced fit" of an enzyme? | The enzyme changes its shape slightly as the substrate binds to it | 86 | |
| 1794698126 | How do enzymes lower activation energy? | By locally concentrating the reactants. One of the ways enzymes work is to increase the concentrations of reactants at a single place. | 87 | |
| 1794698127 | What do the sign and magnitude of the ΔG of a reaction tell us about the speed of the reaction? | Neither the sign nor the magnitude of ΔG have anything to do with the speed of a reaction. | 88 | |
| 1794698128 | If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur? | Nothing; the reaction will stay at equilibrium. | 89 | |
| 1794698129 | Some bacteria are metabolically active in hot springs because | their enzymes have high optimal temperatures. | 90 | |
| 1794698130 | If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to | add more of the enzyme. | 91 | |
| 1794698131 | Which of the following metabolic processes can occur without a net influx of energy from some other process? ADP +(P) i → ATP + H20 or C6H12O6 + 6 O2 → 6 CO2 + 6 H2O | C6H12O6 + 6 O2 → 6 CO2 + 6 H2O | 92 | |
| 1794698132 | Most cells cannot harness heat to perform work because | temperature is usually uniform throughout a cell. | 93 | |
| 1794698133 | Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______. | xergonic; endergonic | 94 | |
| 1794698134 | closed system | A system in which energy, but not matter, is exchanged with its surroundings. | 95 | |
| 1794698135 | open system | A system in which both energy and matter are exchanged with the surroundings. | 96 | |
| 1794698136 | kelvin | A unit of absolute temperature and symbolized as K. Formerly known as degree Kelvin. | 97 | |
| 1794698195 | allosteric inhibition | The process in which an enzyme's activity is changed because of binding to the allosteric site., two active sites; one site for inhibitor, changes shape of other active site to become inactive |  | 98 |
