Bio 101 Campbell Ch 7

Front 1

Selective permeability

Back 1

A property of biological membranes that allows some substances to cross more easily than others.

Front 2

Fluid mosaic model

Back 2

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

Front 3

Peripheral proteins

Back 3

A protein appendage loosely bound to the surface of a membrane and not embedded in the lipid bilayer.

Front 4

Transport proteins

Back 4

A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane.

Front 5

Concentration gradient

Back 5

An increase or decrease in the density of a chemical substance in an area. Cells often maintain concentration gradients of ions across their membranes. When a gradient exists, the ions or other chemical substances involved tend to move from where they are more concentrated to where they are less concentrated.

Front 6

Osmosis

Back 6

The diffusion of water across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration

Front 7

Osmoregulation

Back 7

control of water balance when necessary for adaptation for life. ex paramecium has a contractile vacuole that acts as a pump

Front 8

Turgid

Back 8

Very firm. A walled cell become turgid if it has a greater solute concentration than its surroundings, resulting in entry of water.

Front 9

Plasmolysis

Back 9

plasmolysis
A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall when the cell loses water to a hypertonic environment.

Front 10

Facilitated diffusion

Back 10

The spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients.

Front 11

Gated channels

Back 11

A protein channel in a cell membrane that opens or closes in response to a particular stimulus.

Front 12

Active transport

Back 12

The movement of a substance across a biological membrane against its concentration or electrochemical gradient with the help of energy input and specific transport proteins.

Front 13

Sodium-potassium pump

Back 13

an active transport protein in the plasma membrane of animal cells that transports sodium out of the cell and potassium into the cell against their concentration gradients.

Front 14

Membrane potential

Back 14

The charge of + and - ions between a cell’s cytoplasm and the extracellular fluid. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances.

Front 15

Electrochemical gradient

Back 15

The diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to move relative to the membrane potential.

Front 16

Electrogenic pump

Back 16

An ion transport protein that generates voltage across a membrane.

Front 17

Proton pump

Back 17

main electrogenic pump of plants, fungi and bacteria; its a transport protein that generates a voltage across a membrane

Front 18

Cotransport

Back 18

The coupling of the downhilldiffusion of one substance to the uphilltransport of another against its own concentration gradient.

Front 19

HYPERTONIC

Back 19

high area of solute, low concentration of solvent; A is hypertonic to B; cell loses water and shrinks

Front 20

ISOTONIC

Back 20

mostly constant, equal solute to solvent; yet equilibrium is never truly reached

Front 21

HYPOTONIC

Back 21

low are of solute, high concentration of solvent; B is hypotonic to A; cell gains water and grows

Front 22

What are the staple ingredients of the plama membrane?

Back 22

- Lipids and proteins
- To a lesser extent, carbohydrates

Front 23

What is the most abundant lipid in the plasma membrane?

Back 23

Phosopholipids

Front 24

What is AMPHIPATHIC?

Back 24

A phosopholipid is amphipatic in that it has both hydrophilic and hydrophobic regions.

Front 25

What is an INTEGRAL PROTEIN?

Back 25

A protein that pentrates th hydrophobic core of the lipid bilayer.
- Many can be transmembrane prtoein, which completely span the membane

Front 26

EXOCYTOSIS vs ENDOCYTOSIS

Back 26

how large molecules exit and enter the cell; secretory cells use exo to export their products and cells take in macromolecules by forming vesicles in endo; uses opposing proteins; requires energy

Front 27

Types of endocytosis

Back 27

Pinocytosis (cellular drinking), phagocytosis (cellular eating) and receptor-mediated (use of protein)

Front 28

What is PASSIVE TRANSPORT?

Back 28

no ATP required, moves down concentration gradient from high to low; diffusion is a form if it

Front 29

Types of DIFFUSION?

Back 29

Simple - pass phospholipid through plasma membrane on own
Facilitated - need a transport protein. ex aquaporin - for water only

Front 30

What is OSMOSIS?

Back 30

water diffusion only

Front 31

Fluidity of membranes

Back 31

phospholipids in the pm can move within the bilayer; most of the lipids, and proteins, drift laterally; rarely does a molecule flip flop, membrane must remain fluid to work properly

Front 32

6 major functions of membrane proteins

Back 32

transport, enxymatic actinity, signal transduction, cell-cell recognition, intercellular joining, attachment to the cytoskeleton and extracellular matrix

Front 33

cell to cell recognition

Back 33

by binding to surface molecules, often carbs, on pm. Membrane carbs bond to lipids and proteins forming glycolipids and glycoproteins

Front 34

permeability of lipid layer

Back 34

layer is hydrophobic (nonpolar) and only molecules that can dissolve can pass thru; polar (sugar) molecules cannot pass easily

Front 35

transport proteins

Back 35

(carrier proteins) allow passage of hydrophilic substances across membrane

Front 36

aquaporins

Back 36

channel proteins that facilitate the passage of water