Active Transport

lipid bilayer (cell membrane)

the hydrophilic heads are on the inner and outer surface and the hydrophobic tails in the middle

active transport

the movement of materials through a cell membrane using energy

passive transport

the movement of substances across a cell membrane without the use of energy by the cell

Active Transport

the moving of substances across the cell membrane AGAINST the concentration gradient (from low to high) using ENERGY.

isotonic cell environment

water concentration inside the cell is the same as water concentration outside of the cell - no net movement of water occurs

Semi-permeable membrane

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

Phospholipid

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

Vesicle

A temporary "storage tank"

Phagocytosis

A type of active transport - A type of endocytosis, also known as "cellular eating," this occurs when the cell surrounds a food particle and draws it into the cell. (ENTERS)

Exocytosis

A type of active transport - Process by which a cell releases large amounts of material (Exits)

Endocytosis

A type of active transport - The cell engulfs large molecules and draws them into the cell, allowing them to enter against the concentration gradient (low to high). (ENTERS)

Protein Pump

A type of active transport - a type of cell membrane protein used to move small things against the concentration gradient (against diffusion)

Osmosis

Diffusion of water through a selectively permeable membrane

Diffusion

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

Homeostasis

The process of maintaining stable conditions inside a cell. For example, the concentration of salts, nutrients, and other substances must be kept within a certain range.

Hydrophobic

Water hating

Hydrophilic

Water loving

hypertonic cell environment

a solution in which there is a higher concentration of water molecules (solvent) inside a cell than outside a cell - there is net water movement out of the cell. Water goes out of cell, causing crenation (shriveling)

hypotonic cell environment

a solution in which there is a higher concentration of water molecules (solvent) outside a cell than inside a cell. Cells without walls will swell and burst (lyse) if excess water is not removed from the cell.

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

facilitated diffusion

passive transport using carrier proteins