Slide 1 / 142 Slide 2 / 142 Biology Energy Processing www.njctl.org Slide 3 / 142 Vocabulary Click on each word below to go to the definition. Acetyl Co-A electron transport chain aerobic ethanol fermentation anabolic pathway facultative anaerobe anaerobic FADH 2 ATP fermentation ATP synthase glycolysis Calvin Cycle Krebs cycle catabolic pathway lactic acid fermentation cellular respiration light dependent reactions chlorophyll light independent reactions metabolism citric acid cycle NADH cyclic energy transport electron acceptor NADPH
Slide 4 / 142 Vocabulary Click on each word below to go to the definition. noncyclic energy transport obligate aerobe obligate anaerobe oxidation oxidative phosphorylation phosphorylation photosynthesis photosystem I photosystem II p y r u v a t e pyruvate decarboxylation r e d u c t i o n t h y l a k o i d Slide 5 / 142 Energy Processing Unit Topics Click on the topic to go to that section · Metabolism & ATP · Cellular Respiration · Fermentation · Photosynthesis Slide 6 / 142 Chapter 8 Metabolism & ATP Return to Table of Contents
Slide 7 / 142 Metabolic Pathways Metabolism is the totality of an organism’s chemical reactions. Metabolism is a property of all life. Slide 8 / 142 Metabolic Pathways A metabolic pathway begins with a specific molecule and ends with a product Each step is catalyzed by a specific enzyme Without enzymes, metabolic pathways would proceed very slowly. enzyme 3 enzyme 1 enzyme 2 A B C D Reaction 1 Reaction 2 Reaction 3 Starting Product Molecule Slide 9 / 142 Metabolic Pathways There are two types of metabolic pathways: Catabolic pathways Anabolic pathways
Slide 10 / 142 Catabolic Pathways Catabolic pathways break down molecules from the environment. Living things use the energy derived from breaking the bonds in these molecules to build structures and drive cell processes. Slide 11 / 142 Exergonic Reaction Catabolic pathways are exergonic reactions; the change in Gibbs free energy is negative. Thus, they release energy and occur spontaneously Amount of Reactants free energy released Free energy (ΔG<0) Energy Products Progress of the reaction Slide 12 / 142 Anabolic Pathways Anabolic pathways synthesize complex organic molecules and power cell processes using the energy derived from catabolic pathways. Examples: building bones building muscle building starch powering active transport Click here for a pneumonic device
Slide 13 / 142 Endergonic Reaction Anabolic pathways are endergonic reactions; the change in Gibbs free energy is positive. Thus, they require an input of energy and do not occur spontaneously Amount of Products free energy Free energy required (ΔG > 0) Energy Reactants Progress of the reaction Slide 14 / 142 Spontaneous Processes A process will occur spontaneously if the result is a reduction of the Gibbs Free Energy (G) of the system. G takes into account the resulting change in the energy of a system and the change in its entropy . If the effect of a reaction is to reduce G, the process will proceed spontaneously. If ∆G is negative , the reaction will occur spontaneously. If ∆G is zero or positive , it will not occur spontaneously. Slide 15 / 142 Free Energy and Metabolism Biological systems often need an endergonic reaction to occur, but on it's own, it won't proceed spontaneously. To be able to occur, the endergonic reaction is coupled to a reaction that is exergonic , so that together , they are exergonic.
Slide 16 / 142 Adding Coupled Reactions Non-spontaneous reaction: ∆ G is positive NH 2 NH 3 Glu + ∆ G = +3.4 kcal/mol Glu Ammonia Glutamic acid Spontaneous Reaction: ∆G is negative ∆ G = -7.3 kcal/mol ATP P i + + H 2 O ADP together, reactions are ∆G = –3.9 kcal/mol spontaneous Slide 17 / 142 1 A spontaneous reaction _____. A occurs only when an enzyme or other catalyst is present B cannot occur outside of a living cell C releases free energy when proceeding in the forward direction D is common in anabolic pathways E leads to a decrease in the entropy of the universe Slide 18 / 142 2 Anabolic pathways are ___________ and catabolic pathways are ______________. spontaneous, non-spontaneous A endergonic, exergonic B exergonic, endergonic C endothermic, endergonic D
Slide 19 / 142 3 Which of the following correctly states the relationship between anabolic and catabolic pathways? Degradation of organic molecules by anabolic pathways A provides the energy to drive catabolic pathways. Energy derived from catabolic pathways is used to drive the B breakdown of organic molecules in anabolic pathways. Anabolic pathways synthesize more complex organic C molecules using the energy derived from catabolic pathways. Slide 20 / 142 Cell Energy A cell does three main kinds of work: Mechanical (motion) · Transport (crossing a barrier) · Chemical (changing a molecule) · To do work, cells manage energy resources by energy coupling, using an exergonic reaction to drive an endergonic one Slide 21 / 142 ATP Cells can store the energy from catabolic pathways in a molecule called ATP (adenosine triphosphate) . ATP can be broken down later to fuel anabolic reactions.
Slide 22 / 142 ATP ATP (adenosine triphosphate) includes three phosphate groups (PO 4-3 ). Each Phosphate group has an ionic charge of -3e. In this model of ATP, each PO 4-3 is circled in blue. Slide 23 / 142 ATP The phosphate groups repel each other, since they each have a negative charge. Therefore it requires Work to add the second phosphate group; to go from AMP (monophosphate) to ADP (diphosphate). To add the third group, to go from ADP to ATP (triphosphate), requires even more work since it is repelled by both of the other phosphate groups. Slide 24 / 142 ATP This is like the work in compressing a spring. The energy from the work needed to bring each phosphate group to the molecule is stored in that phosphate bond. When the bond is broken to go from ATP to ADP, significant energy is released. Going from ADP to AMP releases less energy, since there is less total charge in ADP than ATP.
Slide 25 / 142 ATP The bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis. Energy is released from ATP when the terminal phosphate bond is broken. The released energy is equal to the work that was done to form the bond. That work overcame the electrostatic repulsion between the last phosphate group and the initial ADP molecule. The result is a chemical change to a state of lower free energy. Slide 26 / 142 ATP In the living systems, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction. Overall, the coupled reactions are exergonic. Slide 27 / 142 ATP Performs Work ATP drives endergonic reactions by phosphorylation , transferring a phosphate group to some other molecule, such as a reactant. The recipient molecule is now "phosphorylated". The three types of cellular work are powered by the hydrolysis of ATP.
Slide 28 / 142 ATP Performs P Work i P Motor protein Protein moved Mechanical work: ATP phosphorylates motor proteins Membrane protein ADP + ATP P P i P i Solute Solute transported Transport work: ATP phosphorylates transport proteins P NH 2 NH + + P i Glu 3 Glu Reactants: Glutamic acid Product (glutamine) and ammonia made Chemical work: ATP phosphorylates key reactants Slide 29 / 142 The Regeneration of ATP ATP is a renewable resource that is regenerated by addition of a phosphate group to ADP The energy to phosphorylate ADP comes from catabolic reactions in the cell The chemical potential energy temporarily stored in ATP drives most cellular work Each cell is converting millions of ATP to ADP and back again every second. Slide 30 / 142 The Regeneration of ATP ATP Energy from Energy for catabolism cellular work ADP + P i (exergonic, (endergonic, energy energy yielding consuming processes) processes)
Slide 31 / 142 4 In general, the hydrolysis of ATP drives cellular work by _____. A releasing free energy that can be coupled to other reactions Breleasing heat Cacting as a catalyst D lowering the free energy of the reaction Slide 32 / 142 5 What best characterizes the role of ATP in cellular metabolism? The release of free energy during the hydrolysis of ATP A heats the surrounding environment. The free energy released by ATP hydrolysis may be coupled B to an endergonic process via the formation of a phosphorylated intermediate. C It is catabolized to carbon dioxide and water. D The ΔG associated with its hydrolysis is positive. Slide 33 / 142 6 Which of the following is not an example of the cellular work accomplished with the free energy derived from the hydrolysis of ATP? Mechanical work, such as the movement of the cell A Transport work, such as the active transport of an ion into a B cell. Chemical work, such as the synthesis of new proteins. C The production of heat, which raises the temperature of the D cell.
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