Biology Chapter: Energy and Metabolism

Life Requires Energy

• All life requires energy
• Thermodynamics is the study of the energy of systems
• Bioenergetics is the study of how energy flows through living organisms

Metabolism

• All the chemical reactions performed by a living organism.
• Catabolic pathways break down molecules into smaller molecules which are used to generate energy and chemical building blocks
• Anabolic pathways use energy provided by catabolism to drive the synthesis of other molecules

Examples:

• Sucrose is broken down into monosaccharides in a catabolic pathway
• Monosaccharides are broken down further until they are ultimately converted into CO2 and water
• This process is used to generate the energy currency ATP
• Glucose ingested from a donut is stored in the form of glycogen for later use in an anabolic pathway
• This process requires input of energy

Metabolism

• The breakdown of glucose into CO2 is a catabolic pathway
• Metabolism can be very complicated

Forms of Energy

• Kinetic energy is energy associated with the movement of objects
• Potential energy is energy possessed by matter due to its location or spatial arrangement

Kinetic Energy

• Kinetic energy can take the form of thermal energy
• Thermal energy is kinetic energy associated with the random movement of atoms or molecules

Potential Energy

• Potential energy can be found in the arrangement of bonds between atoms
• Chemical energy is potential energy available for release in a chemical reaction

Thermodynamics

• Thermodynamics is the study of energy transformations
• A system is the object or group of objects under study
• Isolated systems freely exchange neither matter nor energy with the surroundings
• Open systems exchange matter and energy with the surroundings

Laws of Energy Transformations

• The first law of thermodynamics states that energy can be transferred and or transformed, but it cannot be created or destroyed
• The second law of thermodynamics states that every energy transfer or transformation increases the entropy of the universe
• Entropy is a measure of disorder

Gibbs Free Energy (G)

• Gibbs Free Energy (G) is the portion of a system's energy that can perform work (at constant temperature and pressure)
• Free energy change (ΔG) tells us if a reaction is thermodynamically favourable but not if it will occur
• ΔG = Gfinal state – Ginitial state

Change in Gibbs Free Energy

• ΔG tells us whether a reaction will be spontaneous or not
• An endergonic reaction has a positive ΔG and is not spontaneous
• An exergonic reaction has a negative ΔG and is spontaneous

Explore the fundamental concepts of energy requirements for life and metabolism in this quiz. Understand thermodynamics, bioenergetics, and the differences between catabolic and anabolic pathways. Test your knowledge on how organisms convert energy and the processes involved in metabolism.