Energy Concepts and Thermodynamics

Energy Concepts

• Kinetic energy is energy associated with motion
• Thermal energy is the kinetic energy associated with the random movement of atoms or molecules
• Heat is thermal energy in transfer between objects
• Potential energy is energy that matter possesses because of its location or structure (e.g., energy in a battery)
• Chemical energy is potential energy available for release in a chemical reaction
• Energy can be converted from one form to another

Laws of Energy Transformation

• Thermodynamics is the study of energy transformations
• An isolated system, like liquid in a thermos, cannot exchange energy or matter with its surroundings
• In an open system, energy and matter can be transferred between the system and its surroundings
• Organisms are open systems

The First Law of Thermodynamics

• The energy of the universe is constant
• Energy can be transferred and transformed, but cannot be created or destroyed
• The first law is also called the principle of conservation of energy

The Second Law of Thermodynamics

• During every energy transfer or transformation, some energy is unusable and often lost as heat
• Every energy transfer or transformation increases the entropy of the universe
• Entropy is a measure of molecular disorder or randomness

Biological Order and Disorder

• Organisms create ordered structures from less organized forms of energy and matter
• Organisms replace ordered forms of matter and energy with less ordered forms
• For example, animals consume complex molecules in their food and release smaller, lower energy molecules and heat into their surroundings
• Organisms take simple, less organized materials (like food) to build complex, ordered structures (like cells and tissues), while releasing simpler, less organized materials (like heat and waste) back into the environment

ATP Powers Cellular Work

• An exergonic reaction proceeds with a net release of free energy and is spontaneous
• An endergonic reaction absorbs free energy from its surroundings and is nonspontaneous
• A cell does three main types of work: chemical, transport, and mechanical
• To do work, cells manage energy resources through energy coupling, the use of an exergonic process to drive an endergonic one
• Most energy coupling in cells is mediated by ATP

Structure and Hydrolysis of ATP

• ATP (adenosine triphosphate) is the cell's energy shuttle
• ATP is composed of ribose, adenine, and three phosphate groups
• The bonds between the phosphate groups of ATP's tail can be broken by hydrolysis
• Energy is released from ATP when the terminal phosphate bond is broken
• This energy release comes from the chemical change to a state of lower free energy, not from the bonds themselves

How Hydrolysis of ATP Performs Work

• The three types of cellular work are powered by the hydrolysis of ATP
• In the cell, energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction
• Overall, the coupled reactions (exergonic + endergonic) are exergonic
• ATP drives endergonic reactions by phosphorylation, transferring a phosphate group to some other molecule, such as a reactant
• The recipient molecule is now called a phosphorylated intermediate

Explore the fundamental concepts of energy, including kinetic and potential energy, along with the laws of energy transformation. This quiz delves into thermodynamics and the first law, emphasizing the conservation and transfer of energy within systems. Test your understanding of these essential scientific principles.