Transportation across Cell Membranes (II) Part 1

Flashcards covering the fundamental concepts of cell membrane transport, including passive and active transport mechanisms and the effects of tonicity on cells without cell walls.

Selective Permeability

A property of the cell membrane that allows it to control the movement of substances entering and exiting the cell.

Passive Transport

Movement across the cell membrane that does not require ATP; it includes simple diffusion, osmosis, and facilitated diffusion.

Active Transport

Movement across the cell membrane that requires ATP; it includes pumps, endocytosis, and exocytosis.

Small Uncharged Molecules

Substances like $CO_2$ and $O_2$ that can pass through the cell membrane.

Lipid-Soluble Substances

Substances such as hydrocarbons that are able to pass through the lipid bilayer.

Ions

Charged particles like $Na^+$, $K^+$, $H^+$, $Cl^-$, and $Ca^{++}$ that require specific transport mechanisms to cross the membrane.

Simple Diffusion

The movement of molecules from an area of high concentration to an area of lower concentration, following the concentration gradient.

Concentration Gradient

A factor affecting diffusion where a larger difference in concentration between two areas leads to faster diffusion.

Medium of Diffusion

The environment in which diffusion occurs, where the rate follows the order: Air > Liquid > Solid.

Osmosis

The movement of water from an area of high water concentration (lower solute concentration) to an area of lower water concentration (higher solute concentration) across a semi-permeable membrane.

Tonicity

The ability of a solution to cause a cell to gain or lose water.

Isotonic Solution

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

Hypertonic Solution

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

Hypotonic Solution

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

Crenation

The process where animal cells shrivel and die after losing water in a hypertonic solution.

Osmoregulation

Adaptations for the control of water balance that organisms use to maintain their internal environment.

Contractile Vacuole

An organelle found in the protist Paramecium that acts as a pump for osmoregulation as the organism is hypertonic to its environment.