● Respiration, even bigger ATP payoff comes from oxidation of pyruvate in the citric acid cycle. Fermentation, pyruvate cannot be utilized to generate any more ATP ● Both begin in the cytoplasm ● Cell Respiration continues in the mitochondria, fermentation does not utilize the mitochondria ● Oxidative phosphorylation *only* occurs in cell respiration (not fermentation!) Chemiosmosis in Respiration and Photosynthesis There are noteworthy differences between oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts. In mitochondria, the highenergy electrons dropped down the transport chain are extracted from organic molecules (which are thus oxidized), whereas in chloroplasts, the source of electrons is water. Chloroplasts do not need molecules from food to make ATP; their photosystems capture light energy and use it to drive the electrons from water to the top of the transport chain. In other words, mitochondria use chemiosmosis to transfer chemical energy from food molecules to ATP, whereas chloroplasts transform light energy into chemical energy in ATP. Chemistry Chemical bonding Bond Classification Formed When Bond Strength* Between ? atoms Bond / Compou nd Properti es
Ionic Bonds es Transferred (from one atom to another, creating ions ) Electrostatic attraction Relatively weak 47 cal/mol* Metals and Nonmetals (e.g. Na and Cl) Salts, High mp, few atoms, watersoluble Covalent Bonds es Shared Equally (between atoms, es shared in pairs) NONPOLAR BOND COVALENT Strong Single ~80* Double ~150* Triple ~200* Nonmetals and Nonmetals Bonds Nonpolar Tend to be water insoluble es Shared Unequally (between atoms, es shared in pairs) POLAR BOND COVALENT Strong Single ~80* Double ~150* Triple ~200* Nonmetals and Nonmetals Bonds Polar Tend to be water soluble Hydrogen Bonds Covalently bonded H’s attracted to Negative entities Electrostatic attraction H carries partial positive charge (δ+) Relatively Weak ~5* (≤5* in proteins) Between covalently bonded H and some negative entity Contribute to the polarity of molecules, very important in biological molecules Properties of water Property Explanation of property Example of benefit to life Cohesion, adhesion Hydrogen bonds hold water molecules together and adhere them to hydrophilic surface A water column is pulled up through a plant vessel High specific heat Heat is absorbed or released when hydrogen bonds break or form. Water absorbs or releases a large quantity of heat for each degree of Temperature changes in the environment and organisms are moderated
temperature change High heat of vaporization Hydrogen bonds must be broken for water to evaporate Solar heat is dissipated from tropical seas Evaporative cooling Water molecules with high kinetic energy evaporate; remaining molecules are cooler Evaporation of water cools the surfaces of plants and animals Less dense as a solid Hydrogen bonds in ice space water molecules father apart making ice less dense Floating insulates bodies of water so they don’t freeze Versatile solvent
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