Ch 8

• • Metabolic pathways consist of chains and cycles of enzyme-catalysed reactions.
• • Enzymes lower the activation energy of the chemical reactions that they catalyse.
• • Enzyme inhibitors can be competitive or non-competitive
• • Metabolic pathways can be controlled by end-product inhibition.
• threonine -> threonine deaminase -> few other intermediates and enzymes -> isoleucine -> isoleucine binds to allosteric site on threonine deaminase -> threonine deaminase no longer binds to threonine

  
• graph of different types of inhibition

  A) normal

  B) competitive

  C) non-competitive

  D) substrate

  E) rate

  
• • Cell respiration involves the oxidation and reduction of electron carriers
• • Phosphorylation of molecules makes them less stable
• • In glycolysis, glucose is converted to pyruvate in the cytoplasm
• • Glycolysis gives a small net gain of ATP without the use of oxygen
• • In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.
• • In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers, liberating carbon dioxide.
• • Energy released by oxidation reactions is carried to the cristae of the mitochondria by reduced NAD and FAD.
• • Transfer of electrons between carriers in the electron transport chain in the membrane of the cristae is coupled to proton pumping.
• • In chemiosmosis protons diffuse through ATP synthase to generate ATP.
• • Oxygen is needed to bind with the free protons to maintain the hydrogen gradient, resulting in the formation of water.
• • The structure of the mitochondrion is adapted to the function it performs
• • Electron tomography used to produce images of active mitochondria. 3D images of the inside!
• matrix contains enzymes for the krebs cycle and the link reaction
• cristae are projections of the inner membrane that increase surface area allowing for more ETC and ATP synthase
• intermembrane space of mitochondria - protons are pumped into this space by ETC it is very thin allowing concentration gradient to be quickly established
• • Light-dependent reactions take place in the intermembrane space of the thylakoids.
• • Light-independent reactions take place in the stroma.
• • Reduced NADP and ATP are produced in the light-dependent reactions.
• • Absorption of light by photosystems generates excited electrons
• • Photolysis of water generates electrons for use in the light-dependent reactions.
• • Transfer of excited electrons occurs between carriers in thylakoid membranes
• • Excited electrons from Photosystem II are used to contribute to generate a proton gradient (some energy from the e- is used to actively pump H+ ions )
• • ATP synthase in thylakoids generates ATP using the proton gradient
• • Excited electrons from Photosystem I are used to reduce NADP
• • In the light-independent reactions a carboxylase catalyses the carboxylation of ribulose bisphosphate (carboxylase aka rubisco)
• • Glycerate 3-phosphate is reduced to triose phosphate using reduced NADP and ATP.
• • Triose phosphate is used to regenerate RuBP and produce carbohydrates (2 of them go off to form glucose and the rest reform RuBP)
• • Ribulose bisphosphate is reformed using ATP
• • The structure of the chloroplast is adapted to its function in photosynthesis
• calvins lollipop - replaced the 12CO2 supplied to the algae with 14CO2 -> took samples of the algae at very short time intervals -> showed what carbon compounds are present at what times -> calvin cycle
• chloroplast has thylakoids, a stack of thylakoids is a granum
• photosystem 2 is first