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Metabolism
Metabolism
Energy
Energy conversions
Metabolic pathways
Catalyst
Enzymes (proteins)
Transformation of matter and energy
Bioluminescence
Laws of Thermodynamics
Catabolic - breakdown pathways – release energy
Anabolic – synthesis pathways – consume energy
Energy coupling
ATP
Cellular Respiration (glucose  CO2 + H2O + ATP)
Biosynthetic pathways (use energy)
Photosynthesis (CO2 + H2O + sunlight energy  O2 + glucose)
Forms of Energy
Kinetic energy
Heat = thermal energy
Potential energy
Chemical energy
Thermodynamics
System
Closed system
Open system
First Law of Thermodynamics
Energy cannot be created or destroyed
Principle of the conservation of energy
Second Law of Thermodynamics
Every energy transformation/transfer increases the entropy (disorder) of the universe
Low-entropy islands
Free energy
Spontaneous reactions
Non-spontaneous reactions
Gibbs free energy (G)
Enthalpy change (∆H)
Change in entropy (∆S)
∆G = Gfinal - Ginitial
Equilibrium
Maximum stability
Endergonic Reactions
Exergonic Reactions
ATP – Energy Currency of the Cell
Three main kinds of work
Mechanical
Transport
Chemical
ATP (adenosine triphosphate)
Type of nucleotide with an adenine, a ribose, and 3 phosphate groups
Energy shuttle
Terminal phosphate bond
ATP hydrolysis
Phosphorylation
Regeneration of ATP
ADP and phosphate
ATP + H2O  ADP + Pi (∆G = -7.3 kcal/mol)
Phosphorylated intermediate
Energy Barriers
Enzymes
Catalyst
Unstable state
Activation energy. (EA)
Activation Barrier
Substrate
Enzyme-substrate complex
3-D structure of an enzyme
Active site
Induced fit
Substrate Specificity
Catalytic cycle
Orienting substrates correctly
Straining substrate bonds and forcing transition states
Providing a favorable microenvironment (such as specific pH)
Covalently bonding (temporarily) to the substrate (direct participation)
Denature
Cofactors
Coenzymes
Enzyme inhibitors
Noncompetitive inhibitors
Competitive inhibitors
Optimal temperature
Optimal pH
Coenzymes
Cofactors
Allosteric regulation
Feedback inhibition
Cooperativity
Enzyme location
Embedded in phospholipid bilayers
In solution within an organelle (lysosomes)
Metabolic order
Respiration
Cellular Respiration - Yields up to 38 ATP/Glucose molecule
Solar Energy
Catabolic pathways
Organic fuels
Sugar (C6H12O6)
Exergonic rxn: ∆G = -686 kcal/mol of Glucose
Fermentation - Yields 2 ATP/Glucose molecule
Glycolysis
Redox rxns
Oxidation
Reduction
Electron transfer
Electronegative nucleus
Reducing agent
Oxidizing agent
Electron shuttle
NAD+
NADH
Coenzyme
Electron transport chain (ETC)
Inner mitochondrial membrane
Degree of electron sharing in covalent bonds
Citric Acid Cycle
Kreb’s Cycle
Substrate level phosphorylation
Oxidative phosphorylation
Glucose
Pyruvate
Acetyl CoA
ATP
Stages of Cellular Respiration
1. Glycolysis
– Breaks down glucose into two molecules of pyruvate
– Produces net 2 ATP and 2 NADH
Conversion of pyruvate to acetyl CoA yields 2NADH
2. The citric acid cycle
– Completes the breakdown of glucose
– Produces net 2 ATP, 6 NADH and 2 FADH2 from 2 pyruvate
3. Oxidative phosphorylation
– Is driven by the electron transport chain (receives electrons from NADH and
FADH2)
Energy investment phase of glycolysis – uses 2 ATP, yields 2 glyceraldehyde-3phosphate
Energy payoff phase of glycolysis yields 4 ATP, 2NADH, 2 pyruvate per glucose
Final Products from 1 Glucose = 2 ATP + 2 pyruvate + 2NADH
Glycolysis - Occurs in the cytoplasm
Pyruvate enters mitochondria by active transport – converted to Acetyl CoA
Multienzyme complex
Mitochondrial matrix
Citric acid cycle completes the oxidation of the sugar
Oxaloacetate
Citrate
FADH2
Ultimately get CO2, NADH, FADH2, and ATP from the CAC.
Pyruvate  AcetylCoA  Citric Acid Cycle
Yield from each pyruvate molecule
• 3CO2 (one is from conversion of pyruvate to Acetyl CoA)
• 4NADH (one is from conversion of pyruvate to Acetyl CoA)
• FADH2
• 1 ATP
Oxidative phosphorylation
Chemiosmosis
Electron Transport Chain
ATP Synthesis
Inner mitochondrial membranes
Cristae
Electronegativity
Electron Acceptors
O2 – Final Electron Acceptor
Ubiquinone
Multiprotein Complexes (I – IV)
Proton Gradient
Proton-motive Force
ATP Synthase Complexes
Complete oxidation of 1 mole of glucose releases 686 kcal of Energy
Phosphorylation of ADP  ATP stores 7.3 kcal/mol
Respiration makes 38 ATP (x 7.3 kcal/mol) = 277.4 kcal (40% of 686 kcal)
Electrons from NADH and FADH2
Fermentation
Alcohol fermentation
Ethanol
Acetaldehyde (2-C)
Lactic acid fermentation
Lactate
Facultative anaerobes
Feedback inhibition
Deaminated
Gylcerol
Fatty acids
Beta oxidation
Biosynthesis (Anabolic Pathways)
Feedback Mechanisms
Allosteric enzymes
Photosynthesis
Photosynthesis
solar (light) energy
chemical energy
Autotroph
Photoautotroph
Producer
Heterotroph
Consumer
Plastids
Chloroplasts
Mesophyll
Thylakoid
Thylakoid membrane
Stroma
Grana
Chlorophyll
Splitting of Water
Redox reaction
Two Stages of Photosynthesis
The Light Reactions - Occur in the grana
– Split water, release oxygen, produce ATP, form NADPH
The Calvin Cycle - Occurs in the stroma
– Forms sugar from carbon dioxide, using ATP for energy and NADPH for
reducing power
Light = electromagnetic energy, which travels in waves
Wavelength
Crest
Trough
Electromagnetic spectrum
Visible light (380-750 nm)
Absorb
Reflect
Transmit
Photosynthetic Pigments
Absorption spectrum
Spectrophotometer
Action spectrum
Photosynthetic Pigments
Chlorophyll a
Chlorophyll b
Accessory pigment
Ground state
Excited state
Fluoresces
Carotenoids
photoprotection
Excitation of Chlorophyll by Light
Chlorophyll absorbs energy
A Reaction Center
Light-Harvesting Complexes
Primary electron acceptor
The Reaction Center
Photosystems I and II
Noncyclic Electron Flow
– Is the primary pathway of energy transformation in the light reactions
– It involves both photosystems
– Produces NADPH, ATP, and oxygen
Cyclic Electron Flow
– Photoexcited electrons take an alternative path
– Uses Photosystem I only
– Electrons cycle back to the first ETC
– Only ATP is produced
Chemiosmosis: Redox reactions of electron transport chains generate a H+ gradient
across a membrane. ATP synthase uses this proton-motive force to make ATP
The Calvin Cycle
• uses ATP and NADPH to convert CO2 to sugar
– Is similar to the citric acid cycle
– Occurs in the stroma
• has three phases
– Carbon fixation
– Reduction
– Regeneration of the CO2 acceptor
ribulose bisphosphate = RuBP
Rubisco (ribulose bisphosphate carboxylase/oxygenase)
Glyceraldehyde-3-phosphate
Photorespiration
Adaptations to Hot, Arid Climates
Alternative mechanisms of carbon fixation
C4 plants – spatial separation of C-fixation
Bundle sheath cells
Oxaloacetate
Malate
Malic Acid
Phosphophenolpyruvate
PEP carboxylase
CAM plants – temporal separation of C-fixation
Crassulacean Acid Metabolism
Vacuole