Bio 201 Chapter 5: Biological Membranes

Front 1

Plasma Membrane

Back 1

The selectively permeable surface membrane that encloses the cell contents and through which all materials entering or leaving must pass.

Front 2

Amphipathic Molecules

Back 2

A molecule containing both hydrophobic and hydrophilic regions.

Front 3

Fluid Mosaic Model

Back 3

The currently accepted model of the plasma membrane and other cell membranes in which protein molecules "float" in a fluid phospholipid bilayer.

Front 4

Integral Membrane Proteins

Back 4

A protein that is tightly associated with the lipid bilayer of a biological membrane.

Front 5

Transmembrane Proteins

Back 5

An integral protein that spans across the lipid bilayer.

Front 6

Peripheral Membrane Proteins

Back 6

A protein associated with one of the surfaces of a biological membrane.

Front 7

Glycoproteins

Back 7

A protein with covalently attached carbohydrates.

Front 8

Selectively Permeable Membrane

Back 8

A membrane that allows some substances to cross it more easily than others.

Front 9

Carrier Protein

Back 9

Proteins that changes in shape to bind to ions or molecules to move that molecule across the membrane.

Front 10

Carrier Mediated Transport

Back 10

Any form of transport across a membrane-bound transport protein with a binding site for a specific substance.

Front 11

Channel Proteins

Back 11

Proteins that form tunnels through the cell membrane.

Front 12

Porins

Back 12

Transmembrane proteins that allow various solutions or water to pass through membranes.

Front 13

Aquaporins

Back 13

Transmembrane proteins that function as gated water channels.

Front 14

Diffusion

Back 14

The net movement of particles from a region of higher concentration to a region of lower concentration.

Front 15

Concentration Gradient

Back 15

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

Front 16

Dynamic Equilibrium

Back 16

The condition of a chemical reaction when the rate of change in one direction is exactly the same as the rate of change in the opposite direction.

Front 17

Osmosis

Back 17

The net movement of water by diffusion through a selectively permeable membrane from a region of higher concentration to a region of lower concentration.

Front 18

Osmotic Pressure

Back 18

The pressure that must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water from the side containing pure water.

Front 19

Isotonic

Back 19

A solution that has identical concentrations of solute and the same osmotic pressure.

Front 20

Hypertonic

Back 20

A solution with an osmotic pressure greater than that of the solution it is being compared to.

Front 21

Hypotonic

Back 21

A solution with an osmotic pressure lower than that of the solution being compared.

Front 22

Turgor Pressure

Back 22

Hydrostatic pressure that develops within a walled cell when the osmotic pressure of the cell's contents is greater than the osmotic pressure of the surrounding fluid.

Front 23

Plasmolysis

Back 23

The shrinkage of cytoplasm and pulling away of the plasma membrane from the cell wall when a walled cell loses water.

Front 24

Facilitated Diffusion

Back 24

The passive transport of ions or molecules by a specific carrier protein in a membrane.

Front 25

Liposomes

Back 25

Artificial vesicles surrounded by a phospholipid bilayer.

Front 26

Active Transport

Back 26

Transport of a substance across a membrane that does not rely on the potential energy of a concentration gradient for the substance being transported; therefore requires an additional source of energy.

Front 27

Sodium-Potassium Pump

Back 27

Active transport system that transports sodium ions out of and potassium ions into cells.

Front 28

Uniporters

Back 28

Carrier proteins that transport a substance in one direction.

Front 29

Symporters

Back 29

Carrier proteins that move two types of substances in one direction.

Front 30

Antiporters

Back 30

Carrier proteins that move two substances in opposite directions.

Front 31

Cotransport System

Back 31

The active transport of a substance from a region of low concentration to a region of high concentration by coupling its transport to the transport of a substance down its concentration gradient.

Front 32

Exocytosis

Back 32

The active transport of materials in and out of the cell by fusion of cytoplasmic vesicles with the plasma membrane.

Front 33

Endocytosis

Back 33

The active transport of substances into the cell by formation of invaginated regions of the plasma membrane that pinch off and become cytoplasmic vesicles.

Front 34

Phagocytosis

Back 34

"cell eating"; a type of endocytosis by which certain cells engulf food particles, microorganisms, foreign matter, or other cells.

Front 35

Pinocytosis

Back 35

"cell drinking"; a type of endocytosis by which cells engulf and absorb droplets of liquids.

Front 36

Ligand

Back 36

A molecule that binds to a specific site in a receptor or other protein.

Front 37

Desmosomes

Back 37

Buttonlike plaques present on two opposing surfaces that hold cells together by means of protein filaments that span the intercellular space.

Front 38

Plasmodesmata

Back 38

Cytoplasmic channels connecting adjacent plant cells and allowing for movement of molecules and ions between cells.

Front 39

Desmotubule

Back 39

A narrow cylindrical structure in a plasmodesmata that runs through a channel and connects the smooth ER of two adjacent cells.

Front 40

Indirect Active Transport

Back 40

Type of transport in which two solutes are transported at the same time.

Front 41

Receptor-Mediated Endocytosis

Back 41

Specific receptors in coated pits along the plasma membrane bind ligands.

Front 42

Anchoring junctions

Back 42

They are found between cells that form a sheet of tissue; include desmosomes and adhering junctions.

Front 43

Adhering Junctions

Back 43

Junctions that are formed by cadherins that cement cells together.

Front 44

Tight Junctions

Back 44

Seal membranes of adjacent animal cells together preventing substances from moving through the spaces between cells.

Front 45

Gap Junction

Back 45

Form channels that allow communication between the cytoplasm of adjacent cells.