Vocab Unit 1 Chapter 5

Front 1

Active transport

Back 1

The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy

Front 2

Amphipathic

Back 2

Having both a hydrophilic region and a hydrophobic region

Front 3

Diffusion

Back 3

The random thermal motion of particles of liquids, gasses, or solids. In the presence of a concentration or electrochemical gradient, it results in the net movement of a substance from a region where it is more concentrated to a region where it is less concentrated

Front 4

Endocytosis

Back 4

Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane

Front 5

Exocytosis

Back 5

The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

Front 6

Facilitated diffusion

Back 6

The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins requiring no energy expenditure

Front 7

Fluid mosaic model

Back 7

The currently accepted model of a cell membrane structure which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids

Front 8

Hypertonic

Back 8

Referring to a solution that when surrounding a cell will cause the cell to lose water

Front 9

Hypotonic

Back 9

A solution that when surrounding a cell will cause the cell to take up water

Front 10

Integral protein

Back 10

A transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein)

Front 11

Isotonic

Back 11

A solution that, when surrounding a cell causes no net movement of water into or out of the cell

Front 12

Ligand

Back 12

A molecule that binds specifically to another molecule usually a larger one

Front 13

Ligand-gated ion channel

Back 13

A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule allowing or blocking the flow of specific ions. Also called an ionotropic receptor

Front 14

Osmosis

Back 14

The diffusion of free water molecules across a selectively permeable membrane

Front 15

Passive transport

Back 15

The diffusion of a substance across a biological membrane with no expenditure of energy

Front 16

Peripheral proteins

Back 16

Proteins loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer

Front 17

Phagocytosis

Back 17

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals

Front 18

Phosphorylation cascade

Back 18

A series of chemical reactions during cell signaling mediated by enzymes (kinases) in which each kinase in turn phosphylates and activates another ultimately leading to phosphorylation of many proteins

Front 19

Pinocytosis

Back 19

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes

Front 20

Protein kinase

Back 20

An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein

Front 21

Protein phosphatase

Back 21

An enzyme that removes phosphate groups from dephosphorylates proteins often functioning to reverse the effects of of a protein kinase

Front 22

Selective permeability

Back 22

A property of biological membranes that allows them to regulate the passage of substances across them

Front 23

Receptor mediated endocytosis

Back 23

The movement of specific molecules into a cell by the inward budding of vesicles containing proteins with receptor sites specific to the molecules being taken in. It enables the cell to acquire bulk quantities of specific substances

Front 24

Second messengers

Back 24

A small nonprotein water soluble molecule or ion such as a calcium ion or cyclic AMP that relays a signal to a cell's interior in response to a signaling molecule bound by a signal receptor protein

Front 25

Signal transduction pathway

Back 25

A series of steps linking a mechanical, chemical, or electrical stimulus to a specific cellular response

Front 26

Tonicity

Back 26

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