Metabolic Pathways Study Notes

Processes that extract energy and reducing power, synthesize building blocks, and construct macromolecules.

The breakdown of fuels and large molecules into smaller, simpler molecules, releasing energy.

The synthesis of complex molecules from simpler precursors, requiring energy.

The energy currency of life, used to power energy-consuming processes.

The change in free energy that occurs when a reaction takes place under standard conditions (1 atm pressure, 298K, 1M concentrations).

The change in free energy that occurs under biochemical standard conditions (pH 7, 55M H2O).

A measure of the ratio of products to reactants at equilibrium.

The actual ratio of products to reactants at a given moment, not necessarily at equilibrium.

A reaction that is spontaneous, releases free energy, and has a negative ΔG.

A reaction that is not spontaneous, requires free energy, and has a positive ΔG.

The process of coupling an unfavorable reaction to a favorable reaction to drive it forward.

The central metabolic pathway that breaks down glucose into pyruvate, producing ATP and reducing power in the form of NADH.

The process of converting pyruvate to lactate or ethanol, regenerating NAD+ and producing ATP.

A key enzyme in glycolysis that converts fructose-6-phosphate to fructose-1,6-bisphosphate, committing glucose to glycolysis.

The process of generating ATP through the oxidation of pyruvate, releasing CO2 and reducing power in the form of NADH and FADH2.

A molecule that carries acetyl groups (2 carbons) in both catabolic and anabolic pathways.

The movement of electrons from a reducing agent to an oxidizing agent, releasing energy.

An electron carrier molecule that accepts electrons during oxidation reactions.

An electron carrier molecule that receives electrons during oxidation reactions.

The process by which electrons from NADH and FADH2 are passed down a chain of carriers, releasing energy to generate ATP.

The energy stored in the form of a proton gradient across a membrane, used to drive ATP synthesis.

The process of using the proton motive force to generate ATP.

The conversion of pyruvate to acetyl-CoA, linking glycolysis to the TCA cycle.

The first step in the TCA cycle, where acetyl-CoA is added to oxaloacetate to form citrate.

An enzyme that catalyzes the isomerization of citrate to isocitrate, the main substrate for the next reaction in the TCA cycle.

An enzyme that catalyzes the oxidative decarboxylation of isocitrate to α-ketoglutarate, generating NADH and releasing CO2.

An enzyme that catalyzes the oxidative decarboxylation of α-ketoglutarate to succinyl-CoA, generating NADH and releasing CO2.

An enzyme that catalyzes the conversion of succinyl-CoA to succinate, generating ATP through substrate-level phosphorylation.

An enzyme that catalyzes the oxidation of succinate to fumarate, generating FADH2.

An enzyme that catalyzes the hydration of fumarate to malate.

An enzyme that catalyzes the oxidation of malate to oxaloacetate, generating NADH.

Biological catalysts that speed up reactions without being consumed in the process.

The minimum amount of energy needed for a reaction to occur.

A temporary, high-energy intermediate formed during a reaction, bridging the gap between reactants and products.

The specific region on an enzyme where substrate binds and catalysis occurs.

A model that describes how enzymes and their substrates change shape upon binding, creating a tighter fit and enhancing catalysis.

A measure of an enzyme's overall efficiency, calculated as Kcat divided by KM.

An inhibitor that binds to the active site of an enzyme, competing with the substrate for binding.

A type of inhibition where the inhibitor binds to the enzyme-substrate complex, preventing product formation.

A form of inhibition where the inhibitor can bind to either the free enzyme or the enzyme-substrate complex, reducing enzyme activity.

The Lineweaver-Burk plot allows you to visualize enzyme kinetics graphically, providing a linear representation of the Michaelis-Menten equation.

In this type of inhibition, the inhibitor mimics the substrate and competes for binding to the active site.

In uncompetitive inhibition, the inhibitor binds to the enzyme-substrate complex, preventing product formation. This results in a decrease in both Vmax and KM.

Noncompetitive inhibition occurs when the inhibitor binds to a different site on the enzyme, affecting its overall function. It reduces Vmax but does not alter KM.

It lowers the activation energy barrier required for a reaction to occur, speeding up the process.

They bind to substrates, bringing them closer together and increasing the frequency of collisions.

Enzymes stabilize the transition state, the high-energy intermediate, by providing a more favorable environment for its formation.

They provide alternative reaction pathways that have lower activation energies, essentially creating a 'shortcut' for the reaction.

This involves the transfer of protons (H+ ions) from one molecule to another, often facilitated by acidic or basic amino acid residues in the active site.

This involves the formation of a temporary covalent bond between the enzyme and the substrate.

This uses metal ions (like zinc, magnesium, or iron) to facilitate the reaction.

This involves the use of electrostatic interactions (like attraction between opposite charges) to stabilize transition states or bring reactants together.

The Michaelis-Menten equation describes the relationship between reaction rate, substrate concentration, Vmax, and KM.

It can be used to graphically represent the relationships between the variables in the Michaelis-Menten equation, providing insights into enzyme kinetics.

It can help identify which type of inhibition is occurring (competitive, uncompetitive, or noncompetitive) by analyzing the plot's changes in slope, X-intercept and Y-intercept.

They are molecules that bind to enzymes and reduce their activity, impacting the overall metabolic process.

They can be naturally occurring compounds, like poisons from plants or toxins from bacteria, or they can be intentionally designed drugs used for therapeutic purposes.