[ GEN BIO ] Lesson 14: Cell’s Transport Mechanism I: Diffusion and Osmosis

Water

is a very essential substance for life to persist; has various properties that help sustain life.

Simple Diffusion

involves the movement of molecules in a solvent from an area of higher solute concentration to an area of lower solute concentration which eventually results in the state of dynamic equilibrium.

Facilitated Diffusion

The channel protein facilitates the movement of molecules.

Facilitated Diffusion

Molecules such as ions and water outside the cell are being transported across the cell membrane through channel proteins via ___.

Simple Diffusion

Area of higher concentration; Equilibrium is achieved

Osmosis

is similar to diffusion. However, ____ refers to the movement of water from higher to lower concentration.

Tonicity

• relative concentration of solutes in fluids

• depends on the concentration of solutes

• ability of a surrounding solution to cause a cell to gain or lose water

• can be isotonic, hypotonic, or hypertonic

• isotonic,

• hypotonic,

• hypertonic

3 kinds of Tonicity (under osmosis)

Isotonic solution

Solutions of equal solute concentration

Isotonic solution

is when water molecules move at the same rate in both directions.

Hypotonic solution

has lower solute concentration and has higher water concentration (i.e., less solute, more water).

Hypotonic solution

can cause the cell to swell or even burst due to the intake of water more than the cell can accommodate.

Hypertonic solution

has higher solute concentration and has lower water concentration (i.e., more solute, less water).

Hypertonic solution

can cause an animal cell to shrink or shrivel due to water loss.

Osmosis

Movement is from the region of high water concentration to one with lower water concentration.

Ok

Plant cells, relative to animal cells, do not change cell size that much with varying concentrations of water.

Diffusion and osmosis both involve movement of molecules without spending energy.

What are the similarities of Diffusion and Osmosis?

Solution

contains both the solute, which is usually solid and a solvent, which is usually a liquid.

Passive Transport

Diffusion is an example of ______ transport in which molecules are moved across the membrane without spending energy.

Facilitated diffusion

involves the movement of molecules across the membrane but with the aid of either channel or carrier proteins. These molecules are usually those that cannot cross due to their molecular size or chemical nature.

Diffusion

is the movement of molecules down their concentration gradient, i.e., from an area of higher concentration to an area of lower concentration.

Osmosis

is the diffusion of water across a selectively permeable membrane from high to low concentration.