Cell Membrane and Cellular Transport Vocabulary

Vocabulary flashcards reviewing key terms regarding cell membrane structures, membrane proteins, osmotic environments, and mechanisms of active and passive cellular transport.

Solute

A substance that dissolves in another substance in a solution, such as salt.

Solvent

The liquid in which a solute is dissolved to make a solution, such as water.

Hypotonic Solution

A solution with a lower solute concentration outside the cell than inside, causing water to rush into the cell and making it swell and potentially burst.

Cytolysis

The bursting of a cell that occurs when water rushes inside due to a hypotonic environment.

Isotonic Solution

A solution with an equal concentration of solute inside and outside of the cell, where water moves in and out at the same rate and the cell remains normal.

Hypertonic Solution

A solution with a higher solute concentration outside the cell than inside, causing water to rush out of the cell and the cell to shrink.

Plasmolysis

The shrinking of a cell that occurs when water rushes out due to a hypertonic environment.

Passive Transport

Cellular transport that does not require energy (ATP) from the cell, moving molecules down or with a concentration gradient from high to low concentration.

Concentration Gradient

The difference in the amount of a solute in a given amount of solution.

Simple Diffusion

A type of passive transport where a substance passes directly through a cell membrane without needing a protein channel, moving from high to low concentration.

Osmosis

The diffusion of water across a semi-permeable membrane from an area of higher water concentration to lower water concentration, or from a lower solute concentration to a higher solute concentration.

Facilitated Diffusion

A type of passive transport where molecules diffuse through transport proteins (channels or carriers) across the cell membrane from high to low concentration without using cell energy.

Active Transport

Cellular transport that requires energy input from the cell in the form of ATP to move molecules against or up a concentration gradient from low to high concentration using protein pumps.

Endocytosis

An active transport process that takes materials into the cell by engulfing matter and enclosing it in a vesicle, such as phagocytosis.

Exocytosis

An active transport process that expels materials out of the cell by vesicles fusing with the cell membrane.

Phospholipid Bilayer

A double layer of phospholipid molecules forming the cell membrane structure, where each layer is a mirror image with polar phosphate heads pointing outward and nonpolar lipid tails pointing inward.

Hydrophilic

Water-loving; attracted to water, describing the polar phosphate heads of phospholipids.

Hydrophobic

Water-fearing; repelling water, describing the nonpolar lipid tails of phospholipids.

Cell-Surface Markers

Membrane proteins attached to carbohydrates on the cell surface that together help other cells recognize specific cell types.

Receptor Proteins

Membrane proteins that recognize and bind to specific substances outside the cell, altering the inside of the cell to detect and respond to environmental changes.

Enzymes (Membrane Proteins)

Proteins in the cell membrane that alter the rate of chemical reactions involved in biochemical processes inside the cell.

Transport Proteins

Membrane proteins (such as protein carriers, protein channels, and protein pumps) that aid the movement of substances across the lipid bilayer into and out of the cell.

Aquaporins

Specific channel proteins in the cell membrane that selectively allow water molecules to pass through during facilitated diffusion.

Sodium-Potassium Pump

A transport protein that uses ATP energy to pump $3$ sodium ions ($Na^+$) out of the cell and $2$ potassium ions ($K^+$) into the cell against their concentration gradient, creating a more positive environment outside the cell.