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Metabolism Chapter 8 (Gibbs free energy- ΔG=ΔH-TΔS also known as Gibbs…

- - - - Exergonic- energy releasing reaction
      - Spontaneous-energy favorable, needs energy to get started then once started can provide energy.
    - - Endergonic- energy consuming reaction,
      - non spontaneous- needs constant energy to continue the reaction
- - - - Cofactors- Many enzymes require non protein helpers for catalytic activity some are inorganic. If the cofactor is an organic molecule it is referred to as a coenzyme.
  - - - The active site and catalytic cycle of an enzyme- an enzyme can convert one or more reactant molecule to one or more reactant molecules.
- - - - metabolic sequence called beta oxidation breaks fatty acids down to 2 carbon fragments and then enter the citric acid cycle as acetyl CoA.
  - - - Anaerobic respiration/fermentation -use of substances other than oxygen as reactant to harvest chemical energy.
        
        Obligate anaerobes- carry out only fermentation or anaerobic respiration, cannot survive in the presence of oxygen
        
        Facultative anaerobes can make enough ATP to survive using fermentation or respiration depending on environment.
        
        Alcohol fermentation- pyruvate is converted into ethanol in two steps releasing CO2 and producing the NAD+ needed for glycolysis. (yeast)
        
        Lactic aid fermentation- pyruvate is reduced directly by NADH to form lactate as an end product, regenerating NAD+ with no release of CO2. (human muscle)
      - Aerobic Respiration-oxygen is consumed as a reactant along with the organic fuel.
        
        Glycolysis- harvest chemical energy by oxidizing glucose to pyruvate
        
        energy investment phase- cell uses 2 ATP to get glucose into 2 ADP and 2 phosphates.
        
        energy payoff phase- Using 4 ADP and 4 phosphates in order to form 4 ATP, then using 2 NAD+, 4 e- and 4 H+ to produce 2NADH, 2 H+,2 Pyruvate and 2 H2O.
        
        Oxidative phosphorylation- Chemiosmosis couples electron transport to ATP synthesis.
        
        electron transport chain- most components of the chain are proteins, using electrons formed from glycolysis and citric acid cycle which move down to a more electro negative electron carrier as it continues releasing free energy breaking a large free energy drop into a series of smaller steps that release energy in manageable amounts.
        
        Chemiosmosis- is an energy coupling mechanism that uses energy stored in the form of H+ gradient across a membrane to drive cellular work. using the proton motive force not only to make 26-28 ATP but also a rotate flagella and pump nutrients/waste across membrane.
        
        Pyruvate oxidation/Citric acid cycle- after pyruvate is oxidized the citric acid cycle completes the energy yielding oxidation of organic molecules
        
        pyruvate oxidation- when pyruvate enters mitochondria it is converted to acetyl CoA through a complex of several enzymes.
        
        Citric acid cycle- (also called Krebs cycle) uses acetyl CoA from pyruvate oxidation in order to produce 2 ATP, 6 NADH and 2 FADH2.
    - - Light reaction - convert solar energy to the chemical energy of ATP and NADPH
        
        water and light are used for this chemical process, electrons stripped from water molecules using energy from light
        
        Oxygen is expelled and hydrogen ion (H+) used to create gradient
        
        NADPH and ADP is used to create ATP and NADP+ is used to create NADPH which are energy carrying molecules that will be used during the dark reaction.
      - Dark reaction AKA CALVIN CYCLE- uses the chemical energy of ATP and NADPH from the light cycle to reduce CO2 into sugar.
        
        Carbon fixation-attaches 5 carbon molecule to a 5 carbon sugar names RuBP, the enzyme that catalyzes this first step is called rubisco. product of this reaction is 2 molecules of 3-phosphoglycerate.
        
        Reduction-the 3 phosphoglycerate gets energy from ATP AND NADPH to make G3P which is either recycled back into rubiso or bonded with another G3P making a compleat sugar.
        
        Regeneration of the CO2 acceptor (RuBP)- the carbon skeletons of G3P are rearranged by the last steps of the Calvin cycle into 3 molecules of RuBP then prepared to receive CO2 again and the cycle continues.
      - Alternative mechanisms of carbon fixation.
        
        CAM plants- fix CO2 at night stoma opens and stores malate in valuoles. Calvin cycle during the day stoma closes and stored malate moves to chloroplast releasing CO2 as byproduct. reduced photorespiration due to high CO2.
        
        C4 plants- uses a 4 carbon compound as its first product using PEP carboxylase enzyme to fix carbon when rubisco cant. the four carbon compound then moves into a bundle sheath then CO2 is released into Calvin cycle.
        
        Photorespiration- occurs when CO2 is low plants use oxygen instead of CO2 in Calvin cycle, this is very bad and the do not survive very long.
        
        C3 plants- first organic product of carbon fixation is a 3 carbon compound made in Calin cycle called PGA, rubisco is the enzyme involved releasing CO2.
      - Chloroplast-cite of photosynthesis in plants mainly in cells of mesphyll, the tissue in the interior of the leaf.
        
        Stomata- microscopic pores in which CO2 enters and oxygen exits.
        
        Stroma- a dense fluid inside a chloroplast double membrane.
        
        Thylakoids- a third membrane system made up of sacs, suspended within the stroma.
        
        Chlorophyll- resides in thylakoid membrane of chloroplast, green pigment that gives leaves its color.
        
        Grana- thylakoid sacs stacked in columns (singular, granum)
    - - Cellular respiration is a spontaneous reaction which releases energy.(exergonic
      - photosynthesis is a non spontaneous reaction that absorbs energy (endergonic.
- - - - Kinetic energy-motion of an object that could produce energy and cause more movement.
        
        Thermal energy- is kinetic energy associated with the random movement of atoms or molecules
        
        Heat- thermal energy in transfer from one object to another
      - Potential energy- Object not presently in motion but because of its structure and location still has energy.
        
        Chemical energy- is potential energy available for release in an chemical reaction.