Chapter 6 - Metabolism: Energy & Enzymes

Fundamentals of biology

Diffusion

A passive process where molecules naturally spread due to random motion, requiring no energy.

Active transport

The process that requires ATP to move molecules against their concentration gradient.

Osmosis

The movement of water across a semi-permeable membrane, moving from low solute to high solute.

Equilibrium

A state where there is equal concentration on both sides of the membrane.

Kinetic energy

Energy possessed by an object due to its motion.

Potential energy

The stored energy in an object due to its position or state, such as chemical energy in food.

First Law of Thermodynamics

Energy is not created or destroyed, but transformed.

Second Law of Thermodynamics

Energy transformations increase entropy, meaning energy is often lost as heat.

Metabolism

The sum of cellular chemical reactions in a cell.

Exergonic reactions

Reactions where products have less free energy than reactants and release energy, occurring spontaneously.

Endergonic reactions

Reactions where products have more free energy than reactants, requiring energy input and are non-spontaneous.

ATP

Adenosine triphosphate, a high-energy compound used to drive metabolic reactions in cells.

Enzymes

Proteins that function as catalysts, accelerating specific reactions by lowering the activation energy.

Induced fit model

A model explaining how enzymes are induced to undergo slight alterations to achieve optimum fit for substrates.

Energy of Activation (Ea)

The minimum amount of energy required to initiate a chemical reaction.

Cofactors

Nonprotein molecules required to activate enzymes.

Competitive inhibition

A type of enzyme inhibition where the inhibitor competes with the substrate for the active site.

Noncompetitive inhibition

A type of enzyme inhibition where the inhibitor binds to an allosteric site, changing the shape of the enzyme without competing for the active site.

Positive feedback

A process that enhances or amplifies changes, often leading to destabilization.

Negative feedback

A process that mitigates or counteracts changes, helping to maintain homeostasis.

Oxidation

The loss of electrons from a molecule.

Reduction

The gain of electrons by a molecule.

OILRIG

An acronym for oxidation is loss, reduction is gain.