Campbell+Biology+Concepts+and+Connections+9th+Ed

Aquaporin

A membrane protein that facilitates the transport of water across the cell membrane.

Phospholipid Bilayer

The double layer of phospholipids that makes up the cell membrane, with hydrophilic heads facing outwards and hydrophobic tails facing inwards.

Passive Transport

The movement of substances across a cell membrane without the use of energy, such as diffusion and osmosis.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water based on solute concentration.

Isotonic Solution

A solution with equal solute concentration compared to the cell, resulting in no net water movement.

Hypertonic Solution

A solution with a higher solute concentration compared to the cell, leading to cell shrinkage.

Hypotonic Solution

A solution with a lower solute concentration compared to the cell, causing the cell to swell.

Active Transport

The movement of substances against their concentration gradient, requiring energy (ATP).

Enzyme

A biological catalyst that speeds up chemical reactions by lowering activation energy.

Substrate

The reactant on which an enzyme works.

Active Site

The specific region of an enzyme where the substrate binds.

Competitive Inhibitor

A substance that competes with the substrate for the active site of an enzyme.

Noncompetitive Inhibitor

A substance that binds to an enzyme at a site other than the active site, changing the enzyme's shape.

Feedback Inhibition

A regulatory mechanism whereby the end product of a metabolic pathway inhibits an early step in the pathway.

Metabolism

The total of all chemical reactions occurring within a cell.

Energy Coupling

The use of energy released from exergonic reactions to drive endergonic reactions.

ATP (Adenosine Triphosphate)

The primary energy carrier in cells, composed of adenosine and three phosphate groups.

Chemical Energy

Potential energy stored in the arrangement of atoms within molecules.

Exocytosis

The process through which a cell expels large molecules or particles by vesicles fusing with the plasma membrane.

Endocytosis

A cellular process in which substances are brought into the cell by engulfing them in a vesicle.

Thermodynamics

The study of energy transformations in a system.