4.1 Energy and Metabolism Flashcards

Comprehensive vocabulary flashcards covering bioenergetics, metabolic pathways, the laws of thermodynamics, and enzyme kinetics and regulation as described in the lecture notes.

Bioenergetics

The term used by scientists to describe the concept of energy flow through living systems, such as cells.

Metabolism

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

Photosynthesis chemical equation

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$$

Cellular Respiration chemical equation

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6H_2O + 6CO_2$$

Adenosine triphosphate (ATP)

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

Metabolic pathway

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

Anabolic pathways

Pathways that require energy to synthesize larger, complex molecules from smaller ones, such as building polymers.

Catabolic pathways

Pathways that generate energy by breaking down complex molecules into simpler ones, such as breaking down polymers into monomers.

Thermodynamics

The study of energy and energy transfer involving physical matter.

Open system

A system where energy can be exchanged with its surroundings; biological organisms are considered open systems.

Closed system

A system that cannot exchange energy with its surroundings.

First law of thermodynamics

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

Second law of thermodynamics

The law stating that energy transfers are never completely efficient and always result in the loss of some energy in an unusable form, typically heat.

Entropy

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

Kinetic energy

The form of energy associated with objects in motion.

Potential energy

Energy that is stored in an object due to its position, structure, or the force of gravity acting on it.

Chemical energy

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

Free energy ($\Delta G$)

Usable energy, or the energy associated with a chemical reaction that is available to do work after accounting for entropy losses.

Exergonic reactions

Spontaneous chemical reactions that have a negative change in free energy ($\Delta G < 0$) and release free energy.

Endergonic reactions

Non-spontaneous chemical reactions that have a positive change in free energy ($\Delta G > 0$) and require an addition of free energy to proceed.

Activation energy

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

Enzymes

Protein catalysts that speed up biochemical reactions by lowering the activation energy without changing the reaction's free energy.

Substrates

The chemical reactants to which a specific enzyme binds.

Active site

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

Denature

An irreversible change in an enzyme's three-dimensional shape and function, often caused by extreme temperatures, pH, or salt concentrations.

Induced fit

A model of enzyme-substrate binding where the interaction causes a mild shift in the enzyme's structure to create an ideal binding arrangement.

Competitive inhibition

A regulatory mechanism where an inhibitor molecule similar to a substrate binds to the active site, blocking the actual substrate.

Noncompetitive inhibition

A mechanism where an inhibitor molecule binds to an allosteric site (a location other than the active site), preventing the substrate from binding.

Allosteric inhibition

Binding of an inhibitor to an allosteric site that induces a conformational change, reducing the affinity of the enzyme's active sites for substrates.

Allosteric activation

Binding of an activator molecule to an allosteric site that increases the affinity of the enzyme's active sites for substrates.

HMG-CoA reductase

The enzyme that synthesizes cholesterol from lipids; it is the drug target for statins.

Cyclooxygenase

The enzyme that is inhibited by acetaminophen (Tylenol) to provide relief from fever and inflammation.

Cofactors

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

Coenzymes

Organic helper molecules, such as those derived from vitamins, required for enzyme function.

Feedback inhibition

A regulatory method where the end product of a metabolic pathway inhibits an upstream enzyme to prevent further production.