Metabolism, ATP and Energy PDF

Metabolism, ATP and energy   **MLO13.**    Defend the importance of ATP as a source of chemical energy that drives biological processes and distinguish between catabolic and anabolic reactions\      **MLO14.**    Explain how energy is generated within a cell and the metabolism of carbohydrates, lip...

Metabolism, ATP and energy   **MLO13.**    Defend the importance of ATP as a source of chemical energy that drives biological processes and distinguish between catabolic and anabolic reactions\      **MLO14.**    Explain how energy is generated within a cell and the metabolism of carbohydrates, lipids and proteins. Detailing the steps involved in glycolysis and the TCA cycle. Explain the importance of mitochondria in oxidative phosphorylation. Gibbs free energy refers to two components: - The enthalpy of the reaction (△H) - The product of entropy and temperature (T) - Enthalpy is the heat energy absorbed when a bond is broken, and it has a negative value - The more negative the enthalpy, the more stable the bond - Entropy refers to the disorder in the system - Temperature x entropy = how much energy is needed to keep and ordered structure from naturally dispersing due to thermal motion - A lower Gibbs value means a more stable molecule △G = △H -- (T) △S If △G is negative, the products have a lower G than the reactants (EXERGONIC) and the reaction will happen spontaneously. If △G is positive, the products have a higher G than the reactants (ENDERGONIC) ATP is important for cell endergonic reactions as it contains the right amount of energy. Therefore, glucose is oxidised in a series of smaller steps, releasing enough energy to synthesize ATP from ADP and Pi. Another example of endergonic reactions that the cell wants to drive using ATP is changes in protein conformation: - The open confirmation of myosin can snap to the closed spontaneously - However, if ADP is bound to the open conformation, then it locks it, preventing it from closing - The open form can also bind to actin, but not actin and ADP simultaneously, thus when the actin binds, it ejects the ADP whilst being dragged backwards - Using the ATP we can bind to myosin, releasing the myosin from the actin fibre - By hydrolysing ATP we can cause the myosin to snap back to the open form, while still being bound to the ADP, locking it in the open conformation, regenerating the cycle