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Metabolism
ability to acquire and use energy.
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Energy
capacity to do work.
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2 Laws of Thermodynamics
- 1. Total amount of energy in universe is constant, energy cannot be created or destroyed, can only change forms.
- 2. Spontaneous direction of energy is from high quality to low quality, each conversion results in production of heat, which is unusable to do work.
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Chemical reaction
refers to interaction between molecules which in turn result in formation of new molecules with different chemical and physical properties.
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Reactants
chemicals that enter into a reaction. (substrates)
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Products
chemicals that are present after the reaction.
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Endergonic reaction
result in products with more energy then reactants had.
2H + O -> H2O
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Exergonic reaction
result in products with less energy then reactants had.
H2O -> 2H + O
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Characteristics of metabolic pathways
most reactions are reversible, all reversible reactions approach a state of dynamic equilibrium.
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Degradative pathways
large molecules, such as carbohydrates, proteins, and lipids are broken down to smaller molecule. Energy is released and used for cellular work.
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Biosynthetic pathways
small molecules are assembled into large ones. A source of energy is required.
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Enzymes
- *proteins that serve as catalysts
- *they are selective
- *they act of specific substrate
- *add -ASE to the end of substrate
- *reused
- *they are denatured by high or low pH, chemicals, radioactivity and high temperature
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Enzyme Structure and Function
active site is a crevice where the substrate binds to the enzyme during reactions. Reactant must reach a transition state in order for the reaction to proceed.
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Activation energy
- the amount of energy needed to bring reactants to the transition state.
- *enzymes increase the rate of reactions by lowering the required activation energy.
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Control of Enzymes activity
- 1. controlling the number of enzymes by speeding up or slowing down enzyme synthesis
- 2. inhibitors can bind with the active site.
- 3. allosteric enzymes have a regulatory site, where control substances can bind, to alter enzymes shape and activity.
- *If this control substance is the end product of a metabolic pathway, feedback inhibition occurs.
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Cofactors
to assist enzymes
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Coenzymes
NAD, FAD; transport hydrogen and electrons
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Inorganic metal ions
Fe++; transport electrons in ETS
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ATP
energy carrier; Adenosine Triphosphate
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ATP/ADP cycle
- *energy input links a phosphate to ADP to form ATP.
- *ATP can donate a phosphate to another molecule (substrate level phosphorylation). That molecule then becomes primed and energized for specific reactions.
- *ATP becomes ADP after the loss of a phosphate.
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2 kinds of Phosphoylation
- 1. substrate level- phosphate transported from one substrate to another.
- 2. electron transport
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Chemosynthetic (autotroph)
extract energy from chemical reactions involving inorganic reactants.
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Photosynthetic (autotroph)
use light energy.
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Heterotrophs
feed on autotrophs, each other and organic waste.
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Aerobic respiration
yields 36 ATP
- *C6H12O6 + 6O2 -> 6CO2 + 6H2O + E
- ^ ^ ^ ^ ^
- gulcose oxygen carbon water energy
- dioxide
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4 series of reactions
- 1. glycolsis
- 2. prior to Krebs cycle
- 3. Krebs cycle
- 4. electron transport phosphorylation
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glycolsis
glucose is broken down to 2 pyruvate. 2 ATPs, 2 NADH are formed
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prior to Krebs cycle
pyruvate is converted to Acetyl CoA. 1 NADH, 1 CO2 is formed.
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Krebs cycle
3 NADH, 1 FADH2, 1 ATP, 2 CO2 are formed.
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Electron transport phosphorylation
32 ATPs are made.
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