Biology (Chapter 5)

• 1972
• This model proposed that the plasma membrane, as well as all membranes, are thin, pliable, bilayers of phospholipids with embedded proteins. 

• Refers to cellular membranes
• They permit some substances to pass through, but block others 

A thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around cells.

Water hating, avoids water

Water loving, attracts to water

Penetrate and are embedded in the phospholipid bilayer, they have one or more hydrophobic regions or domains consisiting of an Alpha-Helix or Beta-Pleated sheet region of the polypeptide. 

Integral proteins that extend from one side of the membrane to the other

Are not embedded in the bilayer, instead they are attached to the inside or the outside surface of the membrane 

Bind specifically with the molecule they assist and are usually selective for one type of molecule

Integral proteins that typically have a hydrophillic interior that provides an aquaous channel for polar molecules, or specific ions to pass when the channel is open 

Phospholipids of the membrane with attached carbohydrate chains

Embedded proteins with attached carbohydrate chains

Requires no cell energy

Requires cell energy

• Active Transport
• A molecular Event, whereby molecules move down a concentration gradient from an area of high concentration to low concentration

• Active Transport
• A diffusion of water

A solvent + a solute 

(Water) the substance usually liquid in nature into which other substances dissolve

The substance that is being dissolved

When the concentration on both sides of a membrane is equal

When the concentration of solute molecules in the cell's environement, outside of the cell is lower than the concentration of solute within the cell 

When the concentration of solute molecules in the cell's environment, outside of the cell is higher than the concentration of solute within the cell

When the concentration of solutes inside and outside the cell are equal

The dissolution or destruction of a cell

the process in plant cells where the cytoplasm pulls away from the cell wall due to the loss of water through osmosis

Specialized channels for the movement of water 

Requires a helper molecule in order to move a polar substance down the concentration gradient from high concentration to low concentration

Specialized integral membrane proteins that take part in communication between the cell and the outside world

• (Na+/K+) 
• Potassium is constantly pumped INTO the cell against the concentration gradient while Sodium ions are constantly pumped OUT of the cell against a similar concentration gradient

Collective term that describes the process of ingesting solid or fluid material by the cell

Highly specific for the molecules that are transported, proteins of the plasma membrane specifically bind particular molecules which may be present in the cellular fluid in low concentrations

• "Cell Eating"
• Material brought inside is solid by nature

• "Cell Drinking" 
• Material brought inside is liquid by nature

The passage of large molecules, waste, neurotransmitters, hormones, and digestive enzymes out of the cell

A bubble-like membranous structure that stores and transports cellular products, and digests metabolic wastes within the cell

The linked, simultaneous transport of two substances across a cell membrane (or another intracellular membrane)