unit 2 exam Ultimate Study Guide

Energy

The fundamental ability to do work.

Work

The movement of matter against opposing forces.

Biological Work

Includes cellular processes such as rearranging atoms during biochemical reactions and moving molecules across cell membranes.

Potential Energy

Stored energy available to perform work, such as that in chemical bonds or concentration gradients.

Kinetic Energy

Energy being used to do work through motion or action, such as movement, heat, light, and sound.

First Law of Thermodynamics

Energy cannot be created or destroyed, only converted from one form into another.

Second Law of Thermodynamics

Energy transfers are inherently inefficient and tend to increase overall disorder, known as entropy.

Entropy

The measure of disorder in a system; increases with energy transformations.

Metabolism

The total sum of all chemical reactions occurring within an organism's cells.

Endergonic Reactions

Reactions that require a net input of energy to proceed, such as photosynthesis.

Exergonic Reactions

Reactions that release net energy as they proceed, such as cellular respiration.

Adenosine Triphosphate (ATP)

The universal energy currency of the cell, storing energy in high-energy phosphate bonds.

ATP Hydrolysis

The process of cleaving a terminal phosphate group from ATP, releasing energy for cellular work.

Phosphorylation

The transfer of a phosphate group from ATP to a recipient molecule, increasing its energy.

Enzymes

Catalytic proteins that accelerate chemical reactions without being consumed.

Active Site

The specific region on an enzyme where substrate molecules bind.

Cofactors

Inorganic substances that assist enzymes during catalysis.

Coenzymes

Organic nonprotein molecules, typically vitamins, that assist enzymes in catalysis.

Passive Transport

Movement of substances across a membrane that does not require cellular energy.

Simple Diffusion

The unassisted movement of solutes across a membrane from high to low concentration.

Facilitated Diffusion

Passive transport that requires a specific transport protein to move solutes across a membrane.

Active Transport

Movement of solutes against their concentration gradient, requiring energy input.

Endocytosis

Process where the cell membrane engulfs external material to form a vesicle.

Exocytosis

Process where intracellular vesicles fuse with the plasma membrane to release their contents.

Homeostasis

The maintenance of stable internal conditions in an organism despite external changes.