Chapter 6 # METABOLISM PowerPoint Image Slideshow

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1 COLLEGE BIOLOGY PHYSICS Chapter 6 # METABOLISM Chapter Title PowerPoint Image Slideshow

2 Figure 8.1 Metabolism

3 Figure 6.2 Energy from the sun. Plants photosynthesis Herbivores eat those plants Carnivores eat the herbivores Decomposers digest plant and animal matter Energy lost as heat

4 Figure 6.4 This tree shows the evolution of the various branches of life. The vertical dimension is time. Early life forms (blue) used anaerobic metabolism

5 Figure 8.UN01 Metabolism & metabolic pathways Anabolism Catabolism Enzyme 1 Enzyme 2 Enzyme 3 A B C D Reaction 1 Reaction 2 Reaction 3 Starting Product molecule

6 Catabolism Break down Complex simple Releases NRG

7 Anabolism Builds up Simple Complex Requires NRG

8 Bioenergetics Energy transformations in living organisms Energy = capacity to cause change

9 Energy Forms Potential Energy Stored energy Capacity to do work Due to: Location Bond arrangement

10 Energy Forms Kinetic Energy Energy of motion Work energy Releases heat

11 Figure 6.8 Examples of endergonic processes (ones that require energy) and exergonic processes (ones that release energy).

12 Figure 8.2 A diver has more potential energy on the platform than in the water. Diving converts potential energy to kinetic energy. Energy Transformations Potential Kinetic Climbing up converts the kinetic energy of muscle movement to potential energy. A diver has less potential energy in the water than on the platform.

13 Figure 8.3 Thermodynamics Energy transformations in matter Matter system Universe surroundings Heat Chemical energy (a) First law of thermodynamics (b) Second law of thermodynamics

14 Figure 8.3a (a) First law of thermodynamics Conservation of energy Chemical energy

15 Figure 8.3b (b) Second law of thermodynamics Transformation ineffincient Heat

16 Figure 6.11 Energy transferred from one system to another and transformed from one form to another.

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18 Figure 6.12 Order & Disorder Entropy is a measure of randomness or disorder in a system. Gases have higher entropy than liquids, and liquids have higher entropy than solids.

19 Entropy Temperature & Entropy gas solid liquid Temperature melting boiling

20 Gibb s Free Energy G = H T S ( G) = change in free energy during a process ( H) = change in enthalpy, or change in total energy ( S) = change in entropy (T) = temperature in Kelvin Only processes with a negative G are spontaneous Spontaneous processes can be harnessed to perform work

21 Figure 8.5 Free energy = energy capable of work Measure instability More free energy (higher G) Less stable Greater work capacity In a spontaneous change The free energy of the system decreases ( G 0) The system becomes more stable The released free energy can be harnessed to do work Less free energy (lower G) More stable Less work capacity (a) Gravitational motion (b) Diffusion (c) Chemical reaction

22 Free energy Figure 8.6a Free Energy and Metabolism (a) Exergonic reaction: energy released, spontaneous Reactants Energy Products Amount of energy released ( G 0) Progress of the reaction

23 Free energy Figure 8.6b Free Energy and Metabolism (b) Endergonic reaction: energy required, nonspontaneous Products Reactants Energy Amount of energy required ( G 0) Progress of the reaction

24 Figure 8.7 Equilibrium and Metabolism G 0 G 0 (a) An isolated hydroelectric system (b) An open hydroelectric system G 0 G 0 G 0 G 0 (c) A multistep open hydroelectric system

25 Figure 8.8 ATP powers cellular work Adenine Phosphate groups Ribose 3 main kinds of cellular work: Chemical/Transport/Mechanical Lowers energy state (a) The structure of ATP Adenosine triphosphate (ATP) Energy Inorganic phosphate Adenosine diphosphate (ADP) (b) The hydrolysis of ATP

26 Figure 8.10 Phosphorylation Transport protein Solute ATP ADP P i P P i Solute transported (a) Transport work: ATP phosphorylates transport proteins. Vesicle Cytoskeletal track ATP ATP ADP P i Motor protein Protein and vesicle moved (b) Mechanical work: ATP binds noncovalently to motor proteins and then is hydrolyzed.

27 Figure 8.11 ATP cycle ATP H 2 O Energy from catabolism (exergonic, energy-releasing processes) ADP P i Energy for cellular work (endergonic, energy-consuming processes)

28 General Enzyme Characteristics Biological catalysts Increases chemical reactions How enzymes work? Lower activation energy Decrease amt of energy needed to get reaction going

29 Figure 8.12 Free energy Decreasing activation energy Progress of the reaction A B C D Transition state A B E A C D Reactants A B G O C D Products

30 Figure 6.15 Free energy Course of reaction without enzyme Reactants Course of reaction with enzyme E A without enzyme E A with enzyme is lower G is unaffected by enzyme Progress of the reaction Products

31 Figure 8.14 Substrate Active site (a) Enzyme (b) Enzyme-substrate complex Specificity resuable

32 Figure Substrates enter active site. 2 Substrates are held in active site by weak interactions. Substrates Enzyme-substrate complex Induced fit Active site Enzyme

33 Figure Substrates enter active site. 2 Substrates are held in active site by weak interactions. Substrates Enzyme-substrate complex 3 Active site can lower E A and speed up a reaction. Active site Enzyme 4 Substrates are converted to products.

34 Figure Substrates enter active site. 2 Substrates are held in active site by weak interactions. Substrates Enzyme-substrate complex 3 Active site can lower E A and speed up a reaction. 6 Active site is available for two new substrate molecules. Enzyme 5 Products are released. Products 4 Substrates are converted to products.

35 Figure 6.16 Enzyme + substrate ES complex NZ + product(s) Induced fit

36 Figure 8.16a Rate of reaction Factors Affect Enzyme Activity Environmental Conditions (Temperature) Optimal temperature for typical human enzyme (37 C) Optimal temperature for enzyme of thermophilic (heat-tolerant) bacteria (77 C) Temperature ( C) (a) Optimal temperature for two enzymes

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38 Figure 8.16b Rate of reaction Factors Affect Enzyme Activity Environmental Conditions (ph) Optimal ph for pepsin (stomach enzyme) Optimal ph for trypsin (intestinal enzyme) ph (b) Optimal ph for two enzymes

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40 Factors Affect Enzyme Activity Environmental Conditions (Ionic concentration)

41 How can you use this to preserve your food items from microorganism that could spoil your meal? Temperature Cooking? Refrigeration? ph Ionic concentration

42 Factors Affect Enzyme Activity Cofactors Inorganic Zn/Fe/Cu Coenzymes Organic Vitamins (B 12 /B 6 ) Binds to active site Stabilizes transition state

43 Figure 8.17 Factors Affect Enzyme Activity (a) Normal binding (b) Competitive inhibition (c) Noncompetitive inhibition Substrate Active site Competitive inhibitor Enzyme Ex. Aspirin, penicillin, nerve gases Sulfonamide para-aminobenzoic aicd (PABA) Nucleic acid synthesis Noncompetitive inhibitor Ex. ATP

44 Figure 8.17 Factors Affect Enzyme Activity (a) Normal binding (b) Competitive inhibition (c) Noncompetitive inhibition Substrate Active site Competitive inhibitor Enzyme Ex. Aspirin, penicillin, nerve gases Sulfonamide para-aminobenzoic aicd (PABA) Nucleic acid synthesis Noncompetitive inhibitor Ex. ATP

45 Figure Two 8.18changed amino acids were found near the active site. Evolution of Enzymes Active site Two changed amino acids were found in the active site. Two changed amino acids were found on the surface.

46 Figure 8.19a (a) Allosteric activators and inhibitors Allosteric enzyme with four subunits Active site (one of four) Regulatory site (one of four) Active form Activator Stabilized active form Ex. Anti-anxiety drugs (Valium, Xanax, Ativan) Oscillation Increase the activity of gamma aminobutyric acid (GABA) Ex. Na + activation of thrombin Ea. AMP Nonfunctional active site Inactive form Inhibitor Stabilized inactive form

47 Figure 8.19a (a) Allosteric activators and inhibitors Allosteric enzyme with four subunits Active site (one of four) Regulatory site (one of four) Active form Activator Stabilized active form Oscillation Ex. Strychnine glycine in CNS Nonfunctional active site Inactive form Inhibitor Stabilized inactive form

48 Figure 6.17 Competitive & noncompetitive Inhibition

49 Figure 6.18 Allosteric Inhibitors

50 Figure 6.18 Allosteric Inhibitors Competitive and noncompetitive inhibition affect the rate of reaction differently. Competitive inhibitors affect the initial rate but do not affect the maximal rate, whereas noncompetitive inhibitors affect the maximal rate.

51 Figure 8.19b (b) Cooperativity: another type of allosteric activation Substrate Inactive form Stabilized active form Hemoglobin

52 Figure 8.20 EXPERIMENT Caspase 1 Active site Substrate SH Known active form SH Active form can bind substrate SH Allosteric binding site Known inactive form Allosteric inhibitor Hypothesis: allosteric inhibitor locks enzyme in inactive form RESULTS Caspase 1 Active form Allosterically inhibited form Inhibitor Inactive form

53 Figure 8.20a EXPERIMENT Caspase 1 Active site Substrate SH Known active form SH Active form can bind substrate SH Allosteric binding site Allosteric Known inactive form inhibitor Hypothesis: allosteric inhibitor locks enzyme in inactive form

54 Figure 8.20b RESULTS Caspase 1 Active form Allosterically inhibited form Inhibitor Inactive form

55 Figure 6.21 Feedback Inhibition An important regulatory mechanism in cells.

56 Figure 8.21 Feedback Inhibition Active site available Initial substrate (threonine) Threonine in active site Isoleucine used up by cell Active site of Feedback enzyme 1 is inhibition no longer able to catalyze the conversion of threonine to intermediate A; pathway is switched off. Isoleucine binds to allosteric site. Intermediate A Intermediate B Intermediate C Intermediate D Enzyme 1 (threonine deaminase) Enzyme 2 Enzyme 3 Enzyme 4 Enzyme 5 End product (isoleucine)

57 Figure 8.22 Mitochondria The matrix contains enzymes in solution that are involved in one stage of cellular respiration. Enzymes for another stage of cellular respiration are embedded in the inner membrane. 1 m