Cell Biology Membrane Transport and Solutions

Practice vocabulary flashcards covering filtration, active transport, tonicity, solution types, osmolarity, facilitated diffusion, and factors influencing diffusion rate.

Filtration

A process used to separate solids from a liquid where hydrostatic pressure or blood pressure forces molecules through a membrane based on the size of the membrane pores.

Active Transport

The movement of molecules from an area of low concentration to an area of high concentration, moving up the concentration gradient.

Isotonic Solution

A solution that contains the same concentration of solute particles as the cell, where water enters and leaves the cell in equal amounts and cell size remains unchanged.

Hypertonic Solution

A solution surrounding a cell that has a greater concentration of non-penetrating solute particles than the cell, resulting in a net movement of water out of the cell so the cell shrinks or crenates.

Hypotonic Solution

A solution surrounding a cell that has a lower concentration of non-penetrating solute particles than in the cell, resulting in a net movement of water into the cell so it swells and may burst (lysis).

Osmolarity

The total concentration of all solute particles in a solution.

Osmotic Pressure

The pressure needed to stop osmosis due to the concentration of non-diffusible solute particles, which increases as osmolarity increases.

Tonicity

The ability of a solution to change the tone or shape of cells by altering its internal water volume.

Facilitated Diffusion

A process where specific protein carrier molecules carry specific molecules through a membrane from areas of high concentration to areas of low concentration.

Carrier Molecule Conformation Model

The model of facilitated diffusion in which a carrier molecule spans the membrane, binds with a molecule, changes its conformation (shape), and expels the molecule on the other side.

Insulin

A substance that promotes the facilitated diffusion of glucose through some cell membranes.

Osmosis

The diffusion of water through a differentially permeable membrane from a high water concentration to a low water concentration.

Lipid Soluble and Nonpolar Substances

Substances such as oxygen ($O_2$), carbon monoxide ($CO$), fat soluble vitamins, and alcohol that pass through the cell membrane by diffusion.

Small and Lipid Insoluble Substances

Substances such as water and small ions ($Na^+$ and $K^+$) that pass through the membrane via pores.

Factors Influencing Diffusion Rate

Variables that determine the speed of net diffusion: concentration difference (greater difference is faster), weight or size of molecules (smaller is faster), and temperature (warmer is faster).

Simple Diffusion

The diffusion of solutes (particles dissolved in water) through a differentially permeable membrane.