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BIOLOGY 1406 CHAPTER 8

METABOLIC PATHWAYS. Metabolism Sum of all chemical activity.Catabolic Pathway Break down molecules.CatabolismAnabolic Pathway Build more complex molecules. AnabolismBioenergetics Study of how organisms manage their energy resources.. Fig. 8-UN1. Enzyme 1. Enzyme 2. Enzyme 3. D. C. B.

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BIOLOGY 1406 CHAPTER 8

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    8. Figure 8.3 Figure 8.3 The two laws of thermodynamics.Figure 8.3 The two laws of thermodynamics.

    11. Figure 8.6 Free energy changes (?G) in exergonic and endergonic reactionsFigure 8.6 Free energy changes (?G) in exergonic and endergonic reactions

    16. Fig. 8-14

    17. Fig. 8-15

    18. Fig. 8-17

    19. Catalysis in the Enzyme’s Active Site In an enzymatic reaction, the substrate binds to the active site of the enzyme The active site can lower an EA barrier by Orienting substrates correctly Straining substrate bonds Providing a favorable microenvironment Covalently bonding to the substrate

    20. Enzyme Inhibitors Competitive inhibitors bind to the active site of an enzyme, competing with the substrate Noncompetitive inhibitors bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective Examples of inhibitors include toxins, poisons, pesticides, and antibiotics

    21. Fig. 8-19

    22. The Evolution of Enzymes Enzymes are proteins encoded by genes Changes (mutations) in genes lead to changes in amino acid composition of an enzyme Altered amino acids in enzymes may alter their substrate specificity Under new environmental conditions a novel form of an enzyme might be favored

    23. Figure 8.18 Figure 8.18 Mimicking evolution of an enzyme with a new function.Figure 8.18 Mimicking evolution of an enzyme with a new function.

    24. Allosteric Regulation of Enzymes Allosteric regulation may either inhibit or stimulate an enzyme’s activity Allosteric regulation occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site

    25. Figure 8.20 Allosteric regulation of enzyme activityFigure 8.20 Allosteric regulation of enzyme activity

    26. Feedback Inhibition In feedback inhibition, the end product of a metabolic pathway shuts down the pathway Feedback inhibition prevents a cell from wasting chemical resources by synthesizing more product than is needed

    27. Figure 8.21 Figure 8.21 Feedback inhibition in isoleucine synthesis.Figure 8.21 Feedback inhibition in isoleucine synthesis.

    28. Specific Localization of Enzymes Within the Cell Structures within the cell help bring order to metabolic pathways Some enzymes act as structural components of membranes In eukaryotic cells, some enzymes reside in specific organelles; for example, enzymes for cellular respiration are located in mitochondria

    29. Figure 8.22 Figure 8.22 Organelles and structural order in metabolism.Figure 8.22 Organelles and structural order in metabolism.

    32. Fig. 8-11

    33. Fig. 8-8

    34. Fig. 8-9

    35. Hydrolysis of ATP The hydrolysis of ATP releases energy Energy promotes molecular change Promotes cellular work.

    36. How the Hydrolysis of ATP Performs Work The three types of cellular work (mechanical, transport, and chemical) are powered by the hydrolysis of ATP In the cell, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction Overall, the coupled reactions are exergonic

    37. Figure 8.9 Figure 8.9 How ATP drives chemical work: Energy coupling using ATP hydrolysis.Figure 8.9 How ATP drives chemical work: Energy coupling using ATP hydrolysis.

    39. Fig. 8-12

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