Biology 3.4 Diffusion and Osmosis

How does facilitated diffusion differ from simple diffusion?

Membrane proteins help move molecules across the membrane.

You have three solutions with different concentrations of particles. Relative to the concentration of particles in a cell, one solution is isotonic, one is hypertonic, and one is hypotonic. 1- Which solution has the highest concentration of particles? 2- Which solution has the highest concentration of water molecules?

1- hypertonic 2- hypotonic (water)

hypertonic solution

A hypertonic solution has a higher concentration of dissolved particles then a cell. This means that the water concentration is higher inside of the cell then outside of the cell. water flows out of the cell, causing it to shrink or even die.

Hypotonic solution

A hypotonic solution has lower concentration of dissolved particles in a cell. This means water molecules are more concentrated outside the cell then inside the cell. If too much water enters a cell the cell membrane could burst.

isotonic solution

A solution is isotonic to a cell if it has the same Concentration of dissolved particles as the cell. Water molecules move in and out of the cell at equal rate, so the cell size remains the same.

In facilitated diffusion, do molecules move down a concentration gradient or against a concentration gradient?

Down a concentration gradient

People with excess energy are described as hyper. How does this relate to the meaning of hypertonic?

Hypertonic means the concentration is higher in the cell than outside the cell. hyper person has excess energy and hypertonic has higher concentration or excess concentration.

In the words iso tonic, hypertonic, and hypo tonic they all share the root word tonic which means pressure there prefix gives them a different meaning.

ISO= equal, same HYPER =over, above HYPO = under, below

facilitated diffusion

Is the diffusion of molecules across a membrane through transport proteins.

The higher the concentration of dissolved particles in a solution, the ______________ the concentration of water molecules in that solution.

Lower

passive transport

The movement of materials through a cell membrane without using energy

The word facilitate means "to make easier" how does this apply to facilitated diffusion?

The transport proteins make it easier for molecules to enter and exit the cell.

Osmosis

Water molecules that move across a semi permeable membrane from an area of higher concentration to an area of lower water concentration

concentration gradient

difference in the concentration of a substance from one location to another

What does it mean for a molecule to diffuse down a concentration gradient?

from one area of higher concentration to a region of lower concentration

What is a concentration gradient?

the difference in the concentration of a substance from one location to another