Cell Transport - Biology

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis

Movement of WATER molecules from an area of higher concentration to an area of lower concentration THROUGH A SEMIPERMEABLE MEMBRANE.

Semipermeable membrane

A membrane that allows some molecules to pass through but does not allow other molecules to pass through

Permeable

allowing to pass or diffuse through

Impermeable

not permitting passage

Passive transport

The movement of substances across a cell membrane, from high to low concentration, without the use of energy by the cell

Active transport

The movement of particles from an area of low concentration to an area of high concentration that requires the cell to use energy.

Phospholipid

Molecule that makes up most of the cell membrane; it contains a polar phosphate head and nonpolar lipid tails.

Channel protein

Protein in the cell membrane that allows certain substances to pass through it.

Free water concentration

"driving" force in osmosis whereby some water molecules cluster around and solute molecules and are unable to diffuse. The free water molecules move from high concentration to low concentration until solute concentration is the same on both sides.

Hypotonic solution

The environment of the cell has more water than the cell, therefore water will move into the cell. It will cause plant cells to swell and animal cells to burst.

Hypertonic solution

The environment of the cell has less water than the cell, therefore water will move out of the cell. It will cause plant cells to experience plasmolysis and animals cells to shrivel up.

Plasmolysis

When a plant cell is in a hypertonic solution its cell membrane will shrink away from the cell wall. This causes plants to wilt.

Isotonic solution

The environment of the cell has an equal amount of water as the cell does. This causes no net change in the cell. Water will move in and out at the same rate.

Concentration Gradient

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

Polar molecule

Molecule with an unequal distribution of charge, resulting in the molecule having a positive end and a negative end

Dynamic equilibrium

Result of diffusion where there is continuous movement of particles but no overall change in concentration.

Osmotic balance

water moving out of cell equals water moving into cell.

Homeostasis

Maintaining a constant internal environment or balance.

Hydrophilic

Water loving

Hydrophobic

Water fearing

Endocytosis

movement of large or groups of small particles into a cell via active transport

Exocytosis

movement of large or groups of small particles out of a cell via active transport

Endosymbiotic theory

eukaryotic organelles evolved from the endocytosis of prokaryotes to form eukaryotes