Chapter 8 - Chapter 8 An introduction to metabolism...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 8 –An introduction to metabolism Metabolic Pathways: Metabolism is the entirety of an organism’s chemical reactions. This is an emergent property that arises from interactions between molecules and the cellular environment. A metabolic pathway is the route of a single specific molecule going through a series of steps and resulting in a certain product. Each step of the pathway is catalyzed by a certain enzyme. Metabolism manages the material and energy resources of a cell. The pathways that release energy when breaking down complex molecules to simpler ones are called catabolic or breakdown pathways . For example, cellular respiration is a major catabolic pathway that releases energy stored to do work. Anabolic or biosynthetic pathways consume energy and build complex molecules from simpler ones. For example, a major anabolic pathway is synthesis of proteins from amino acids. Large molecules Catabolic: Anabolic: Energy stored. Energy released. Small molecules Energy: Bioenergetics - The study of how organisms manage their energy resources. Thermodynamics- The study of energy transformations that occur in a collection of matter. Types: Kinetic: motion Heat/thermal: kinetic based due to random movement of atoms and molecules Potential: location or structure Chemical: available for release in a chemical reaction First Law of Thermodynamics: Energy can be transferred and transformed, but it cannot be created or destroyed. Second Law of Thermodynamics: Every energy transfer or transformation increases the entropy of the universe. Entropy is the disorder or randomness of the universe. In most energy transformations, most usable forms of energy are at least partially converted to heat. The increase in the amount of heat present increases the entropy of the universe. OR For a process to occur spontaneously, it must increase the entropy of the universe. If not then the process is non-spontaneous and requires an input of energy.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Free energy Change, ΔG The Gibbs free energy change measures the portion of a system’s energy that can perform work when temperature and pressure are uniform in a system, as in a living cell. ΔG = ΔH - TΔS Change in free energy Change in system’s enthalpy Absolute temperature * Change in system’s entropy Processes that have a negative ΔG are spontaneous. Therefore, spontaneous reactions decrease the system’s free energy. ΔG = G final - G initial . For ΔG to be negative, G final < G initial , thus the products have less free energy that the reactants and are less likely to change, i.e. more stable. As a reaction tends towards equilibrium, the free energy of the products and reactants decreases, (think of an inverse equation). A process is spontaneous and can do work only when it is moving toward equilibrium. Systems at equilibrium are at a minimum G and can do no work. Free energy and metabolism:
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 5

Chapter 8 - Chapter 8 An introduction to metabolism...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online