What do the membranes provide?

provide the structural basis for metabolic order.

It allows some substances to cross more easily than others.

(pg 79)

(BACKGROUND INFO) For all cells the plasma membrane forms a boundary between the living cell and its surroundings and controls the traffic of molecules into and out of the cell. The plasma membrane takes up substances the cell needs and disposes of the cell's wastes.

Is a protein molecule that functions as a biological catalyst increasing the rate of a reaction without itself being changed into a different molecule.

Resembles the enzymes normal substrate and competes with the substrate for the active site on the enzyme.

Does not enter the active site. It binds to the enzyme somewhere else and its binding changes the shape of the enzyme so that the active site no longer fits the substrate.  (Pg 78)

Of a cell is producing more of that product than it needs, the product may act as an inhibitor of one enzymes of the pathway.  The sort of inhibition whereby a metabolic reaction Is blocked by its product is called feedback inhabitation which regulates metabolism.

A description of membrane structure depicting a cellular membrane as a mosaic of diverse protein molecules embedded in a fluid bilayer made of phospholipid.

Message transfer process. The binding of the messenger to the receptor triggers a chain reaction involving other proteins which relay the message to a molecule that performs a specific activity inside a cell.

Diffusion is the tendency for particles of any kind to spread out evenly in an available space, moving from where they are more concentrated to regions where they are less concentrated.

An increase or decrease in the density of a chemical substance in an area. Cells often maintain concentration gradients of ions across membranes.

The  diffusion of a substance across a biological membrane without any input of energy.

The movement of a substance across a biological membrane against its concentration gradient aided by specific transport  proteins and requiring input of energy (often as ATP)

For Dummies Def: Cell expends energy to move substances across its membranes.

What is tionocity?

A solution having the same solute concentration as another solution.

In comparing two solutions, the one with the lower concentration of solutes.

The control of the gain and loss of water and dissolved solutes in an organism.

A phenomenon that occurs in plants in an hypertonic solution. The cell loses water and shrivels, and its plasma membrane pulls away from the cell wall, usually killing the cell.

The movement of materials out of the cytoplasm of a cell via membranous vesicles or vacuoles.

The movement of materials into the cytoplasm of a cell via membranous vesicles or vacuoles.

Cellular “eating” a type of endocytosis whereby a cell engulfs macromolecules, other cells, or particles into its cytoplasm.

Make energy available for cellular work.