The First Law of Thermodynamics According to the first law of thermodynamics, the energy of the universe is constant: – Energy can be transferred and transformed, but it cannot be created or destroyed The first law is also called the principle of conservation of energy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Second Law of Thermodynamics During every energy transfer or transformation, some energy is unusable, and is often lost as heat According to the second law of thermodynamics: – Every energy transfer or transformation increases the entropy (disorder) of the universe Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Progress of the reaction Fig. 8-6 Reactants Amount of energy released (∆G < 0) Energy Free energy Products Progress of the reaction (a) Exergonic reaction: energy released Products Figure 8.6 Free energy changes (ΔG) in exergonic and endergonic reactions Amount of energy required (∆G > 0) Energy Free energy Reactants Progress of the reaction (b) Endergonic reaction: energy required

Adenine Phosphate groups Ribose Fig. 8-8 Figure 8.8 The structure of adenosine triphosphate (ATP) Ribose

H2O P P P Adenosine triphosphate (ATP) P + P P + Energy Fig. 8-9 P P P Adenosine triphosphate (ATP) H2O Figure 8.9 The hydrolysis of ATP P + P P + Energy i Inorganic phosphate Adenosine diphosphate (ADP)

Fig. 8-10 + ∆G = +3.4 kcal/mol Glutamic acid Ammonia Glutamine NH2 NH3 + ∆G = +3.4 kcal/mol Glu Glu Glutamic acid Ammonia Glutamine (a) Endergonic reaction 1 ATP phosphorylates glutamic acid, making the amino acid less stable. P + ATP + ADP Glu Glu NH2 P 2 Ammonia displaces the phosphate group, forming glutamine. NH3 + + P i Glu Glu Figure 8.10 How ATP drives chemical work: Energy coupling using ATP hydrolysis (b) Coupled with ATP hydrolysis, an exergonic reaction (c) Overall free-energy change

+ H2O Energy for cellular work (endergonic, energy-consuming Fig. 8-12 ATP + H2O Energy from catabolism (exergonic, energy-releasing processes) Energy for cellular work (endergonic, energy-consuming processes) Figure 8.12 The ATP cycle ADP + P i

Electrons carried via NADH Electrons carried via NADH and FADH2 Fig. 9-6-3 Electrons carried via NADH Electrons carried via NADH and FADH2 Oxidative phosphorylation: electron transport and chemiosmosis Glycolysis Citric acid cycle Glucose Pyruvate Mitochondrion Cytosol Figure 9.6 An overview of cellular respiration ATP ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation Oxidative phosphorylation

Oxidative phosphorylation accounts for almost 90% of the ATP generated by cellular respiration A smaller amount of ATP is formed in glycolysis and the citric acid cycle by substrate-level phosphorylation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Enzyme Enzyme ADP P Substrate + ATP Product Fig. 9-7 Figure 9.7 Substrate-level phosphorylation Product

Energy investment phase Fig. 9-8 Energy investment phase Glucose 2 ADP + 2 P 2 ATP used Energy payoff phase 4 ADP + 4 P 4 ATP formed 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+ Figure 9.8 The energy input and output of glycolysis 2 Pyruvate + 2 H2O Net Glucose 2 Pyruvate + 2 H2O 4 ATP formed – 2 ATP used 2 ATP 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Pyruvate Fig. 9-10 CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Figure 9.10 Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the citric acid cycle Pyruvate Coenzyme A CO2 Transport protein

Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle 2 Fig. 9-11 Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle 2 CO2 Figure 9.11 An overview of the citric acid cycle FADH2 3 NAD+ FAD 3 NADH + 3 H+ ADP + P i ATP

Figure 9.13 Free-energy change during electron transport NADH 50 2 e– NAD+ FADH2 2 e– FAD Multiprotein complexes  40 FMN FAD Fe•S  Fe•S Q  Cyt b Fe•S 30 Cyt c1 IV Free energy (G) relative to O2 (kcal/mol) Cyt c Cyt a Cyt a3 20 Figure 9.13 Free-energy change during electron transport e– 10 2 (from NADH or FADH2) 2 H+ + 1/2 O2 H2O

i INTERMEMBRANE SPACE H+ Stator Rotor Internal rod Cata- lytic knob Fig. 9-14 INTERMEMBRANE SPACE H+ Stator Rotor Internal rod Figure 9.14 ATP synthase, a molecular mill Cata- lytic knob ADP + P ATP i MITOCHONDRIAL MATRIX

Electron transport chain 2 Chemiosmosis Fig. 9-16 H+ H+ H+ H+ Protein complex of electron carriers Cyt c V Q   ATP synthase  2 H+ + 1/2O2 H2O FADH2 FAD NADH NAD+ Figure 9.16 Chemiosmosis couples the electron transport chain to ATP synthesis ADP + P ATP i (carrying electrons from food) H+ 1 Electron transport chain 2 Chemiosmosis Oxidative phosphorylation

Fig. 9-17 CYTOSOL Electron shuttles span membrane MITOCHONDRION 2 NADH or 2 FADH2 2 NADH 2 NADH 6 NADH 2 FADH2 Glycolysis Oxidative phosphorylation: electron transport and chemiosmosis 2 Pyruvate 2 Acetyl CoA Citric acid cycle Glucose + 2 ATP + 2 ATP + about 32 or 34 ATP Figure 9.17 ATP yield per molecule of glucose at each stage of cellular respiration About 36 or 38 ATP Maximum per glucose:

(a) Alcohol fermentation Fig. 9-18a 2 ADP + 2 P 2 ATP i Glucose Glycolysis 2 Pyruvate 2 NAD+ 2 NADH 2 CO2 + 2 H+ Figure 9.18a Fermentation 2 Acetaldehyde 2 Ethanol (a) Alcohol fermentation

(b) Lactic acid fermentation Fig. 9-18b 2 ADP + 2 P 2 ATP i Glucose Glycolysis 2 NAD+ 2 NADH + 2 H+ 2 Pyruvate Figure 9.18b Fermentation 2 Lactate (b) Lactic acid fermentation

Ethanol or lactate Citric acid cycle Fig. 9-19 Glucose Glycolysis CYTOSOL Pyruvate O2 present: Aerobic cellular respiration No O2 present: Fermentation MITOCHONDRION Ethanol or lactate Acetyl CoA Figure 9.19 Pyruvate as a key juncture in catabolism Citric acid cycle

Citric acid cycle Oxidative phosphorylation Fig. 9-20 Proteins Carbohydrates Fats Amino acids Sugars Glycerol Fatty acids Glycolysis Glucose Glyceraldehyde-3- P NH3 Pyruvate Acetyl CoA Figure 9.20 The catabolism of various molecules from food Citric acid cycle Oxidative phosphorylation

Fig. 10-3 Leaf cross section Vein Mesophyll Stomata CO2 O2 Chloroplast Mesophyll cell Outer membrane Figure 10.3 Zooming in on the location of photosynthesis in a plant Thylakoid Intermembrane space 5 µm Stroma Granum Thylakoid space Inner membrane 1 µm

Reactants: 6 CO2 12 H2O Products: C6H12O6 6 H2O 6 O2 Fig. 10-4 Figure 10.4 Tracking atoms through photosynthesis

i CO2 Light NADP+ ADP Calvin Cycle Light Reactions ATP NADPH Fig. 10-5-4 H2O CO2 Light NADP+ ADP + P i Calvin Cycle Light Reactions ATP Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle NADPH Chloroplast [CH2O] (sugar) O2

Light Reflected light Chloroplast Absorbed Granum light Transmitted Fig. 10-7 Light Reflected light Chloroplast Figure 10.7 Why leaves are green: interaction of light with chloroplasts Absorbed light Granum Transmitted light

RESULTS Fig. 10-9 Chloro- Chlorophyll b Absorption of light by phyll a Chlorophyll b Absorption of light by chloroplast pigments Carotenoids (a) Absorption spectra 400 500 600 700 Wavelength of light (nm) (measured by O2 release) Rate of photosynthesis Figure 10.9 Which wavelengths of light are most effective in driving photosynthesis? (b) Action spectrum Aerobic bacteria Filament of alga (c) Engelmann’s experiment 400 500 600 700

Electron transport chain Fig. 10-13-5 Electron transport chain Primary acceptor Primary acceptor 4 7 Electron transport chain Fd Pq e– 2 e– 8 e– H2O e– NADP+ + H+ Cytochrome complex 2 H+ NADP+ reductase + 3 1/2 O2 NADPH Pc e– e– P700 5 P680 Light 1 Light 6 6 ATP Figure 10.13 How linear electron flow during the light reactions generates ATP and NADPH Pigment molecules Photosystem I (PS I) Photosystem II (PS II)

Primary acceptor Primary Fd acceptor Fd NADP+ Pq + H+ NADP+ reductase Fig. 10-15 Primary acceptor Primary acceptor Fd Fd NADP+ + H+ Pq NADP+ reductase Cytochrome complex NADPH Pc Figure 10.15 Cyclic electron flow Photosystem I Photosystem II ATP

H+ Diffusion Electron transport chain ADP + P Fig. 10-16 Mitochondrion Chloroplast MITOCHONDRION STRUCTURE CHLOROPLAST STRUCTURE H+ Diffusion Intermembrane space Thylakoid space Electron transport chain Inner membrane Thylakoid membrane Figure 10.16 Comparison of chemiosmosis in mitochondria and chloroplasts ATP synthase Matrix Stroma Key ADP + P i ATP Higher [H+] H+ Lower [H+]

Fig. 10-17 STROMA (low H+ concentration) Cytochrome complex Photosystem II Photosystem I 4 H+ Light NADP+ reductase Light Fd 3 NADP+ + H+ Pq NADPH e– Pc e– 2 H2O 1 1/2 O2 THYLAKOID SPACE (high H+ concentration) +2 H+ 4 H+ To Calvin Cycle Figure 10.17 The light reactions and chemiosmosis: the organization of the thylakoid membrane Thylakoid membrane ATP synthase STROMA (low H+ concentration) ADP + ATP P i H+

Fig. 10-18-3 Figure 10.18 The Calvin cycle Input 3 (Entering one at a time) CO2 Phase 1: Carbon fixation Rubisco 3 P P Short-lived intermediate 3 P P 6 P Ribulose bisphosphate (RuBP) 3-Phosphoglycerate 6 ATP 6 ADP 3 ADP Calvin Cycle 6 3 P P ATP 1,3-Bisphosphoglycerate 6 NADPH Phase 3: Regeneration of the CO2 acceptor (RuBP) 6 NADP+ 6 P i Figure 10.18 The Calvin cycle 5 P G3P 6 P Glyceraldehyde-3-phosphate (G3P) Phase 2: Reduction 1 P Glucose and other organic compounds Output G3P (a sugar)

C4 leaf anatomy The C4 pathway Mesophyll cell Mesophyll cell CO2 Fig. 10-19 C4 leaf anatomy The C4 pathway Mesophyll cell Mesophyll cell CO2 Photosynthetic cells of C4 plant leaf PEP carboxylase Bundle- sheath cell Oxaloacetate (4C) PEP (3C) Vein (vascular tissue) ADP Malate (4C) ATP Pyruvate (3C) Bundle- sheath cell Stoma CO2 Calvin Cycle Figure 10.19 C4 leaf anatomy and the C4 pathway Sugar Vascular tissue

(a) Spatial separation of steps (b) Temporal separation of steps Fig. 10-20 Sugarcane Pineapple C4 CAM CO2 CO2 Mesophyll cell 1 CO2 incorporated into four-carbon organic acids (carbon fixation) Night Organic acid Organic acid Figure 10.20 C4 and CAM photosynthesis compared Bundle- sheath cell CO2 CO2 Day 2 Organic acids release CO2 to Calvin cycle Calvin Cycle Calvin Cycle Sugar Sugar (a) Spatial separation of steps (b) Temporal separation of steps