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Chapter 8 and Chapter 9 (Concept 8.4 (Activation Energy-initial investment…

- - - - starts with a specific molecule then alters in a series of defined steps; results as a certain product
      - each step is catalyzed by a specific enzyme
      - analogous to traffic lights
      - some release energy to break down complex molecules
    - - major pathway- cellular respiration
      - energy from organic molecules become available to in cell
        
        Ciliary beating or membrane transport
    - - consume energy to build molecules
      - biosynthetic pathways
      - synthesis of amino acids from single compounds
        
        synthesis of protein from AA
      - Bioenergetics: study of how energy flows through living organisms
- - - - ATP + H2O yields to ADP, P (exergonic reaction)
  - - - change G is of an endergonic run is less than the amount of E released by ATP hydrolysis, the two rxns can be coupled
        
        coupled rxns are exergonic
  - - - Energy released by breakdown rxns (catabolism) in the cell is used to phosphorylate ADP,regenrating ATP
      - regeneration of ATP is endergonic
      - catabolic pathways provide energy for the endergonic process of making ATP
- - - - portion of system's energy that can perform work when temperature and pressure are uniform throughout the system as in a living cell
      - value for change G depends on pH, temperature, and concentrations of reactants and products
      - every spontaneous process decreases the system's free energy and processes that have a positive or zero change G are never spontaneous
  - - - Ex; a diver on the top of a platform is less stable than when floating in water
    - - Chemical Equilibrium: forward and backward reactions occur at the same rate
      - free energy of the mixture of reactants and products decreases
      - free energy increases when a reaction is pushed away from equilibrium
      - G is at its lowest value
  - - - Change G negative
      - occurs spontaneously
      - Greater the decrease in free energy, the greater the amount of work can be done
        
        Cellular Respiration Reaction: C6H12O6 + 6O2 yields 6CO2 + 6H2O
    - - Change G is positive
      - nonspontaneous
      - uses energy
      - conversion of carbon dioxide and water to glucose and oxygen
  - - - Flows of materials through the cell keeps the metabolic pathways from reaching equilibrium
    - - Cellular Respiration
- - - - Hydrolysis of sucrose
  - - - process by which a catalyst selectively speeds up a rxn w/o itself being consumed
      - enzymes lower activation energy
        
        enzymes cannot make an endergonic reaction exergonic
        
        enzymes are specific for the rxns they catalyze; determine the chemical processes going on in cell
  - - - reactant an enzyme acts on
      - enzyme binds to the substrate forming enzyme-substrate complex
      - catalytic action of enzyme converts substrate to the product
    - - sucrase catalyzes the hydrolysis of sucrose
    - - results from its shape
      - Active site: where the substrate binds to the enzyme
      - specificity of an enzyme is attributed to a complementary fit b/w the shape of its active site and the shape of the substrate
      - induced fit:tightneing of the binding after initial contact
      - brings chemical groups of active site into positions that enhance their ability to catalyze the chemical rxn
  - - - 1) substrates enter the site; enzymes changes the shape such that its active site enfolds the substrates
      - 2) substrates are held in the active site by weak interactions
      - 3) The active site lowers activation energy and speeds up the rxn
      - 4) substrates are converted to products
      - 5) products are released
      - Active site is available for two new substrate molecules
  - - - enzymatic rxn increases w/ increasing temps up to a point
    - - allows greatest number of molecular collisions and fastest conversion of reactants to product molecules
      - human enzymes have optimal temps of 35-40 degrees Celsius
    - - in the range of 6-8 but there are exceptions
      - pepsin work best at a low pH
  - - - if the cofactor is an organic molecule
      - most vitamins act as coenzymes and are important in nutrition
  - - - reduce productivity of enzymes by blocking substrates from entering active sites
      - can be overcome by increasing concentration of substrate so active sites are more available
    - - don't compete directly w/ substrate
      - impede enzymatic rxns by binding to other enzymes
- - - - Fermenation: degradation of sugars or other organic fuel occurs w/o the use oxygen
  - - - Exergonic Process
  - - - Oxidation: loses electrons
      - Reduction: gains electrons
      - electron donor is reducing agent
      - electron acceptor oxidizing agent
      - oxygen is one of the most powerful oxidizing agents
  - - - hydrogen is transferred from glucose to oxygen
  - - - glucose broken down in a series of steps, each catalyzed by an enzyme
    - - well suited as an electron carrier
      - can cycle b/w its oxidized form and its reduced form
      - NAD+ is the most versatile electron acceptor in cellular respiration
    - - consists of a number of molecules mostly proteins, built into the inner membrane of the mitochondria of eukaryotic cells
      - transfer of electrons from NADH to oxygen is an exergonic reaction
      - electrons move down the chain from one carrier molecule to the next in a series of redox rxns
      - Glucose to NADH to ETC to Oxygen
      - Location: innen mitochondrial membrane
      - Reactants: 10 NADH, 2 FADH2, O2, H+, ADP,P
      - Products: H2O, 32 or 34 ATP, NAD+, FAD
  - - - occurs in cytosol
      - degradation process by breaking down glucose into 2 molecules of a compound called pyruvate
    - - ATP Synthesis
      - powered by the redox rxns of the ETC
      - ETC and chemiosmosis make up oxidative phosphorylation
      - 90% of ATP generated by respiration
    - - ATP synthesis
      - enzyme transfers a phosphate group from a substrate molecule to ADP
- - - - cell spends ATP
    - - ATP is produced by substrate-level phosphorylation and NAD+ is reduced to NADH by electrons released form the oxidation of glucose
- - - - Cycle generates 1 ATP per turn by substrate-level phosphorylation
      - also known as Krebs cycle
- - - - Prosthetic groups: nonprotein components such as cofactors and Coenzymes essential for the catalytic functions of certain enzymes
    - - adds its electrons from w/in complex 2 at lower energy level than NADH does
  - - - enzyme that makes ATP from ADP and inorganic phosphate
      - works like an ion pump running in reverse
      - uses energy of an existing ion gradient to power ATP synthesis
    - - process in which energy stored in the form of a hydrogen ion gradient across a membrane is used to drive cellular work such as the synthesis of ATP
      - refers to H ions across a membrane
      - H ion can move back across the membrane, diffusing down its gradient
    - - H ion gradient that results is a proton-motive force
        
        drives H ions back across the membrane through the H ion channels provided by ATP synthases
- - - - pyruvate is converted to ethanol in two steps
        
        1) releases carbon dioxide from the pyruvate which is converted to acetaldehyde
        
        2) Acetaldehyde is reduced by NADH to ethanol
      - yeast to wine
      - yeast to bread
    - - pyruvate is reduced directly by NADH to form a lactate as an end product, regenerating NAD+ w/ no release of CO2
      - bacteria to cheese
      - bacteria to yogurt
      - produces muscle fatigue
      - sugar catabolism for ATP production outpaces the muscle's supply of oxygen from the blood
  - - - Fermentation: final electron acceptor is pyruvate or acetaldehyde
      - Cellular Respiration: electrons carried by NADH are transferred to ETC
    - - Fermentation: yields 2 molecules of ATP
      - Cellular Respiration: Aerobic Respiration yields up to 32 molecules of ATP per glucose molecule
    - - can't survive in the prescence of oxygen
    - - makes ATP by aerobic respiration if oxygen is present
      - muscle cells behave like these anaerobes
      - To make same amount of ATP, these anaerobes have to consume sugar at a faster rate when fermenting than respiring
- - - - starch is hydrolyzed to glucose in the digestive tract
      - glycogen can be hydrolyzed to glucose b/w meals as fuel for respiration
    - - beta oxidation breaks fatty acids down to two-carbon fragments, which enter the citric acid cycle as acetyl CoA
        
        NADH and FADH2 are generated during beta oxidation