1 BIOENERGETICS Energy Flow

2 What is Bioenergetics? energyliving systems organisms The study of energy in living systems (environments) and the organisms (plants and animals) that utilize them

3 Energy Required by all organisms May be Kinetic or Potential energy

4 Kinetic Energy Energy of Motion Heat and light energy are examples

5 Potential Energy Energy of position Energy of position Includes energy stored in chemical bonds Includes energy stored in chemical bonds

6 Two Types of Energy Reactions

7 Endergonic Reactions Chemical reaction energy Chemical reaction that requires a net input of energy. Absorbs free energy and stores it Photosynthesis Photosynthesis 6CO 2 +6H 2 O  C 6 H 12 O 6 + 6O 2 SUN photons Light Energy (glucose)

8 Exergonic Reactions Chemical reactions releases energy Chemical reactions that releases energy Cellular Respiration C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O+ ATP (glucose)Energy

9 Metabolic Reactions of Cells

10 What is Metabolism? sum total chemical activities cells The sum total of the chemical activities of all cells. Managing the material and energy resources of the cell

11 Two Types of Metabolism Catabolic Pathways Catabolic Pathways Anabolic Pathways Anabolic Pathways

12 Catabolic Pathway Metabolic reactions release energy (exergonic)breaking down Metabolic reactions which release energy (exergonic) by breaking down complex molecules in simpler compounds Hydrolysis = add a water molecule to break apart chemical bonds Cellular Respiration Cellular Respiration C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + ATP (glucose) energy

13 Anabolic Pathway Metabolic reactions, consume energy(endergonic),build Metabolic reactions, which consume energy (endergonic), to build complicated molecules from simpler compounds. Dehydration synthesis = removal of a water molecule to bond compounds together Photosynthesis Photosynthesis 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 SU N lightenergy (glucose)

14 Energy Coupling The transfer of energy from catabolism to anabolism Energy from exergonic reactions drive endergonic reactions and vice versa EX. Photosynthesis – cellular respiration cycle

15 Energy Transformation Governed by the Laws of Thermodynamics.

16 1st Law of Thermodynamics Energy can be transferred and transformed, but it cannot be created or destroyed. Also known as the law of Conservation of Energy.

17 2nd Law of Thermodynamics Each energy transfer or transformation increases the entropy of the universe. Entropy = a measure of disorder or randomness HEAT is energy in its most random state.

18 Summary The quantity of energy in the universe is constant, but its quality is not.

19 Free Energy The portion of a system's energy that can perform work. G = H - TS G = free energy of a system H = total energy of a system T = temperature in o K S = entropy of a system

20 Free Energy of a System If the system has: more free energy it is less stable It has greater work capacity Metabolic equilibrium = zero free energy so it can do no workDEAD CELL Metabolic disequilibrium = produces free energy to do work More unstable produces more free energy EX. Greater concentration/ temperature differences

21 Free Energy Changes

22 Spontaneous Process If the system is unstable, it has a greater tendency to change spontaneously to a more stable state. This change provides free energy for work.

23 Chemical Reactions Are the source of energy for living systems. Are based on free energy changes. Exergonic: chemical reactions with a net release of free energy. Endergonic: chemical reactions that absorb free energy from the surroundings. Reaction Types

24 Exergonic/Endergonic

25 3 main kinds of cellular work Mechanical - muscle contractions Transport - pumping across membranes Chemical - making polymers All cellular work is powered by ATP

26 Cell Energy Couples an exergonic process to drive an endergonic one. ATP is used to couple the reactions together.

27 Cellular Energy - ATP

28 ATP Components: Components: 1. adenine: nitrogenous base 2. ribose: five carbon sugar 3.phosphate group: chain of 3 ribose adenine PPP phosphate group

29 Adenosine Triphosphate Three phosphate groups-(two with high energy bonds Three phosphate groups-(two with high energy bonds Last phosphate group (PO 4 ) contains the MOST energy Last phosphate group (PO 4 ) contains the MOST energy All three phosphate groups are negatively charged (repel each other making it very unstable) All three phosphate groups are negatively charged (repel each other making it very unstable)

30 Breaking the Bonds of ATP Occurs continually in cells ATP-ase last PO 4 bond Enzyme ATP-ase can weaken & break last PO 4 bond releasing energy & free PO 4 Phosphorylated Phosphorylated = a phosphate group attaches to other molecules making them more unstable and more reactive (energy boost to do work)

31 How does ATP work ? enzymes energy-rich glucose Organisms use enzymes to break down energy-rich glucose to release its potential energy adenosine triphosphate(ATP) This energy is trapped and stored in the form of adenosine triphosphate(ATP)

32 How Much ATP Do Cells Use? each cell 10,000,000 molecules of ATP per second It is estimated that each cell will generate and consume approximately 10,000,000 molecules of ATP per second

33 Coupled Reaction - ATP exergonic hydrolysis ATP endergonic dehydration process transferring phosphate group The exergonic hydrolysis of ATP is coupled with the endergonic dehydration process by transferring a phosphate group to another molecule. H2OH2OH2OH2O H2OH2OH2OH2O

34 Hydrolysis of ATP ATP + H 2 O  ADP + P (exergonic) Hydrolysis (add water) PPP Adenosine triphosphate (ATP) PP P + Adenosine diphosphate (ADP)

35 Hyrolysis is Exergonic Energy Used by Cells

36 Dehydration of ATP ADP + P  ATP + H 2 O (endergonic ADP + P  ATP + H 2 O (endergonic ) PPP Adenosine triphosphate (ATP) PP P + Adenosine diphosphate (ADP) Dehydration (Remove H 2 O

37 Dehydration is Endergonic Energy is restored in Chemical Bonds

38 ATP in Cells A cell's ATP content is recycled every minute. Humans use close to their body weight in ATP daily. No ATP production equals quick death.

39 What Are Enzymes? Proteins ( Most enzymes are Proteins (tertiary and quaternary structures) Catalyst Act as Catalyst to accelerates a reaction Not permanently Not permanently changed in the process

40 Enzymes catalyze Are specific for what they will catalyze Reusable Are Reusable ase End in –ase-Sucrase-Lactase-Maltase

41 How do enzymes Work? weakening bonds owers Enzymes work by weakening bonds which lowers activation energy

42 Activation Energy Energy needed to convert potential energy into kinetic energy. Potential Energy Activation Energy

43 Enzymes Free Energy Progress of the reaction Reactants Products Free energy of activation Without Enzyme With Enzyme

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46 Enzyme-Substrate Complex substance enzyme substrate The substance (reactant) an enzyme acts on is the substrate Enzyme Substrate Joins

47 Active Site restricted region enzyme bindssubstrate A restricted region of an enzyme molecule which binds to the substrate. Enzym e Substrate Active Site

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49 Models of How Enzymes Work 1. Lock and Key model 2. Induced Fit model

50 Lock and Key Model Substrate (key) fits to the active site (lock) which provides a microenvironment for the specific reaction.

51 Induced Fit shape A change in the shape of an enzyme’s active site Induced Induced by the substrate

52 Induced Fit Model Substrate “almost” fits into the active site, causing a strain on the chemical bonds, allowing the reaction.

53 Enzymes Usually specific to one substrate. Each chemical reaction in a cell requires its own enzyme.

54 Factors that Affect Enzymes Environment (Temperature & pH) Cofactors Coenzymes Inhibitors Allosteric Sites

55 Environment Factors that change protein structure will affect an enzyme. Examples: pH shifts temperature salt concentrations

56 Temperature & pH High temperaturesdenature (Most enzymes like normal body temperatures High temperatures denature enzymes (Most enzymes like normal body temperatures) Most enzymes function near neutral pH (6 to 8) ionic salts Denatured (unfolded) by ionic salts

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58 Cofactors Inorganic substances (zinc, iron, copper) enzymatic activity Inorganic substances (zinc, iron, copper) are sometimes need for proper enzymatic activity. Non-protein helpers can bond to the active site of enzymes to help in reactions Example: Example: Iron Iron must be present in the quaternary hemoglobin structure of hemoglobin in order for it oxygen to pick up oxygen.

59 Coenzymes Organic molecules that act as cofactors which help enzymes. Examples: vitamins

60 Two examples of Enzyme Inhibitors a. Competitive inhibitors: resemble enzyme’s normal substrate competeactive site a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Competitive inhibitor Substrate

61 Inhibitors b. Noncompetitive inhibitors: do not enter the active sitebind to another part enzymeenzymechange its shapealters the active site Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site. Enzyme active site altered Noncompetitive Inhibitor Substrate

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63 Control of Metabolism Is necessary if life is to function. Controlled by switching enzyme activity "off" or "on” or separating the enzymes in time or space. Types of Control 1.Switching on or off the genes that encode for specific enzyme production 2.Allosteric sites 3.Feedback inhibition 4.cooperativity

64 Allosteric Regulation The control of an enzyme complex by the binding of a regulatory molecule. Regulatory molecule may stimulate or inhibit the enzyme complex. Allosteric site is a specific receptor site on some part of the enzyme molecule away from the active site When activated, this site changes the shape of the enzyme to inhibit it or to stimulate it

65 Allosteric Regulation

66 Feedback Inhibition When a metabolic pathway is switched off by its end-product. End-product usually inhibits an enzyme earlier in the pathway. Prevents the cell from wasting chemical resources

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68 Cooperativity One substrate molecule can trigger the same favorable shape-change in all the other subunits of the enzyme Amplifies the response of the enzymes to substrate

69 Review

70 How many high energy phosphate bonds does ATP have?

71 Which is true of photosyntheis? Anabolic or Catabolic ExergonicOrEndergonic

72 The breakdown of ATP is due to: DehydrationorHydrolysis H 2 O addedorH 2 O removed

73 Which Reactions are often Coupled in Organisms Hydrolysis or Dehydration Anabolism or Catabolism EndergonicorExergonic BOTH BOTH BOTH