Cell Transport Mechanisms: Passive Transport

Flashcards for reviewing cell transport mechanisms, focusing on passive transport.

Plasma Membrane

The boundary that separates the living cell from its surroundings and exhibits selective permeability, regulating the cell’s composition.

Passive Transport

A transport mechanism that does not require energy (ATP) for substances to move from an area of higher concentration to an area of lower concentration.

Active Transport

A transport mechanism that requires energy (ATP) for substances to move across cell membranes.

Diffusion (Simple Diffusion)

The random movement of a substance from an area of high concentration to an area of low concentration; a type of passive transport.

Brownian Movement

The inherent vibration of molecules causing them to collide and spread out into available space driving diffusion.

Facilitated Diffusion

A passive transport mechanism where materials diffuse across the plasma membrane with the help of membrane proteins.

Channel Proteins

Integral proteins that provide corridors allowing specific molecules or ions to cross the membrane during facilitated diffusion. Examples are aquaporins and ion channels.

Carrier Proteins

Proteins that bind with a substance and aid its diffusion through the membrane by undergoing a subtle change in shape.

Osmosis

The diffusion of water across a semipermeable membrane down its concentration gradient.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water, affecting the cell's volume by osmosis.

Osmolarity

Describes the solution's total solute concentration.

Isotonic Solution

A solution where the solute concentration outside the cell is the same as inside the cell, resulting in no net water movement.

Hypertonic Solution

A solution where the solute concentration outside the cell is greater than inside the cell, causing the cell to lose water.

Hypotonic Solution

A solution where the solute concentration outside the cell is less than inside the cell, causing the cell to gain water.

Osmoregulation

The control of solute concentrations and water balance, a necessary adaptation for life in hypotonic or hypertonic environments.

Turgid

The state of a plant cell in a hypotonic solution, where it swells until the cell wall opposes water uptake, making the cell firm.

Flaccid

The state of a plant cell in an isotonic solution, where there is no net movement of water, causing the cell to become limp.

Plasmolysis

The process in a plant cell where, in a hypertonic environment, the membrane pulls away from the cell wall due to water loss, a usually lethal effect.