Energy and Metabolism Practice Flashcards

Flashcards covering the concepts of bioenergetics, metabolic pathways, the laws of thermodynamics, kinetic and potential energy, and enzyme function and the function and regulation of enzymes based on the OpenStax Concepts of Biology notes.

Bioenergetics

A term scientists use to describe the concept of energy flow through living systems, such as cells.

Metabolism

The sum of all chemical reactions that take place inside cells, including those that consume or generate energy.

Metabolic pathway

A series of chemical reactions that takes a starting molecule and modifies it, step-by-step, through a series of metabolic intermediates to yield a final product.

Anabolic pathways

Metabolic pathways that require an input of energy to synthesize complex molecules from simpler ones, such as building polymers.

Catabolic pathways

Metabolic pathways in which complex molecules are broken down into simpler ones, releasing energy; an example is breaking down polymers into monomers.

Adenosine triphosphate (ATP)

The primary energy currency of all cells, used to perform immediate work.

Enzyme

A protein that functions as a catalyst to facilitate or speed up biological chemical reactions by lowering activation energy.

Thermodynamics

The study of energy and energy transfer involving physical matter.

Open system

A system, such as a biological organism, in which energy can be exchanged with its surroundings.

Closed system

A system that cannot exchange energy with its surroundings.

First law of thermodynamics

A physical law stating that the total amount of energy in the universe is constant and conserved; energy cannot be created or destroyed, only transferred or transformed.

Second law of thermodynamics

A physical law stating that every energy transfer or transformation is never completely efficient, resulting in the loss of some unusable energy, typically in the form of heat energy.

Entropy

The measure of randomness or disorder within a system; high disorder is associated with high entropy and low energy.

Kinetic energy

The type of energy associated with objects or molecules in motion.

Potential energy

Stored energy an object possesses due to its position, structure, or state, such as water held behind a dam.

Chemical energy

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

Free energy

Usable energy, or energy that is available to do work after energy losses (such as heat) are accounted for; it is signified as $\Delta G$ (delta G).

Exergonic reactions

Chemical reactions that release free energy, resulting in a negative change in free energy ($-\Delta G$); these are also referred to as spontaneous reactions.

Endergonic reactions

Non-spontaneous chemical reactions that absorb free energy, resulting in a positive change in free energy ($+\Delta G$).

Activation energy

The small amount of energy input necessary for all chemical reactions to occur.

Substrates

The specific chemical reactants to which an enzyme binds.

Active site

The unique location within an enzyme where the substrate binds and the chemical reaction takes place.

Denature

An irreversible change in the three-dimensional shape and function of an enzyme, often caused by extreme temperature, pH, or salt concentration.

Induced fit

A model of enzyme action describing the dynamic interaction where the enzyme undergoes a mild shift in structure to form an ideal binding arrangement with the substrate.

Competitive inhibition

A mechanism of enzyme regulation where an inhibitor molecule similar to a substrate binds to the active site, blocking the actual substrate from binding.

Noncompetitive inhibition

A type of enzyme inhibition where an inhibitor binds to a location other than the active site, preventing the substrate from binding.

Allosteric site

A location on an enzyme, other than the active site, where regulatory molecules (inhibitors or activators) bind.

Allosteric inhibition

A process where an inhibitor molecule binds to an allosteric site, inducing a conformational change that reduces the enzyme's affinity for its substrate.

Allosteric activation

A process where an activator molecule binds to an allosteric site, inducing a conformational change that increases the affinity of the enzyme's active site for its substrate.

Cofactors

Inorganic helper ions, such as iron and magnesium, required by some enzymes to function optimally.

Coenzymes

Organic helper molecules, often derived from vitamins, that are required for enzyme action and are recycled and reused.

Feedback inhibition

A cellular regulatory mechanism where the end product of a metabolic pathway inhibits an upstream enzyme to regulate its own further production.

HMG-CoA reductase

The specific enzyme that synthesizes cholesterol from lipids in the body and serves as the drug target for statins.