chapt04

Energy

The ability to do work.

Potential Energy

Stored energy available to do work.

Kinetic Energy

Energy being used to do work.

First Law of Thermodynamics

Energy cannot be created or destroyed, only converted.

Second Law of Thermodynamics

All energy transformations are inefficient and result in energy loss as heat.

Metabolism

Chemical reactions inside cells.

Endergonic Reaction

A reaction that requires an input of energy.

Exergonic Reaction

A reaction that releases energy.

Chemical Equilibrium

A state where the rates of product and reactant formation are equal.

Oxidation

Loss of electrons, which releases energy.

Reduction

Gain of electrons, which requires energy.

ATP (Adenosine Triphosphate)

The energy currency of the cell that stores and transfers energy.

Phosphorylation

The transfer of a phosphate group to a molecule, which energizes it.

Enzyme

An organic molecule that catalyzes (speeds up) a chemical reaction without being consumed.

Active Site

The region of an enzyme where substrates bind.

Cofactor

A non-protein molecule that assists an enzyme in its activity.

Feedback Inhibition

A regulatory mechanism in which the end product of a reaction inhibits an enzyme involved in its formation.

Diffusion

The process of molecules moving from an area of high concentration to an area of low concentration.

Facilitated Diffusion

The process of passive transport of molecules across a membrane via a protein transporter.

Active Transport

The movement of molecules against their concentration gradient, requiring energy.

Endocytosis

The process of engulfing fluids and large molecules into the cell.

Exocytosis

The process of transporting fluids and large particles out of the cell.

Concentration Gradient

A difference in the concentration of a substance across a space.

Isotonic Solution

A solution with equal concentrations of solute inside and outside the cell.

Hypotonic Solution

A solution with a lower concentration of solute compared to the cell's interior.

Hypertonic Solution

A solution with a higher concentration of solute compared to the cell's interior.