BIOL 1414 Lecture 8: Energy and Metabolism

Vocabulary flashcards covering the fundamentals of bioenergetics, metabolic pathways, laws of thermodynamics, ATP, and enzyme regulation based on biology lecture notes.

Bioenergetics

The study of energy flow through living systems, including the synthesis and metabolic breakdown of complex molecules.

Metabolism

All chemical reactions occurring within a cell, including those that use energy and those that release energy.

Exergonic

Chemical reactions that release energy during the process.

Endergonic

Chemical reactions that require an input of energy to occur.

$ATP$ (Adenosine triphosphate)

The primary energy currency of cells, consisting of a small, simple molecule with high-energy bonds used to power cellular work.

Metabolic pathway

A series of interconnected biochemical reactions that convert substrate molecules into final products through a step-by-step process.

Anabolic pathway

A metabolic pathway that requires energy to synthesize complex molecules from simple ones, such as building proteins from amino acids.

Catabolic pathway

A metabolic pathway that releases energy by breaking down complex molecules, such as the breakdown of glucose which can yield $36-38$ units of $ATP$.

Kinetic energy

The energy associated with objects in motion, such as light or a rapidly moving molecule.

Potential energy

Energy that results from the potential to do work, such as a wrecking ball hanging above the ground.

Chemical energy

A type of potential energy that exists within chemical bonds and is released when those bonds are broken.

Free energy ($G$)

Also known as Gibbs Free Energy, it is the usable energy available to do work after accounting for entropy.

Entropy

A measure of randomness or disorder within a system; all chemical reactions lose some energy to the environment as heat, which contributes to entropy.

Exergonic reaction

A spontaneous energy-releasing reaction where the change in free energy is negative ($\Delta G < 0$).

Endergonic reaction

A non-spontaneous reaction that requires an input of free energy and results in a positive change in free energy ($\Delta G > 0$).

Chemical equilibrium

A state where a reversible reaction proceeds in both directions until it reaches the lowest possible free energy and maximum entropy.

Activation Energy ($E_A$)

The energy input required for a chemical reaction to occur, reaching the high-energy and unstable transition state.

Heat Energy

Energy transferred from one system to another without doing work, which increases molecular motion and helps reach the transition state.

Thermodynamics

The study of energy and energy transfer involving physical matter.

Open system

A system in which energy can be transferred between the system and its environment; biological organisms are considered open systems.

First Law of Thermodynamics

The law stating that the total amount of energy in the universe is constant and cannot be created or destroyed.

Second Law of Thermodynamics

The law stating that every energy transfer involves some loss of energy in an unusable form (heat), meaning entropy in the universe is constantly increasing.

Hydrolysis

The process of breaking down a molecule, such as $ATP$, by adding a water molecule.

Energy coupling

A process where the energy generated from one reaction drives a second, energy-requiring reaction.

Phosphorylation

The addition of a phosphate group to a molecule, such as when $ATP$ releases a phosphate that attaches to a protein.

Substrates

The specific chemical reactants to which an enzyme binds.

Active site

The specific location within an enzyme where the substrate binds and the chemical reaction occurs.

Induced Fit Model

The theory that a mild shift occurs in the enzyme's structure upon substrate binding to ensure an ideal arrangement for catalysis.

Competitive inhibition

A form of enzyme regulation where a molecule similar to the substrate binds to the active site and blocks the substrate from binding.

Allosteric inhibition

A process where an inhibitor molecule binds to a non-active site, causing a shape change that reduces the enzyme's affinity for its substrate.

Cofactors

Inorganic helper molecules, such as the zinc ion required by DNA Polymerase, that promote optimal enzyme function.

Coenzymes

Organic helper molecules, such as vitamin C, that are required for certain enzymes to function properly.

Feedback inhibition

A regulatory mechanism where the product of a metabolic pathway binds to an enzyme to slow down its own further production.