Cellar Processes

Homeostasis: when cells and organisms maintain a constate state of balance.

Semipermeable Membrane: membrane that only allows certain substances and keep others out.

Molecule that can pass freely across the cell membrane: nonpolar (lacking in chemical polarity.)

Molecules that cannot pass freely across the membrane: polar (slightly positively charged @ one end of the molecule, negative at the other end.)

Diffusion: when a substance moves from an area of high concentration to a lower one; active.

Osmosis: Diffusion of water across the cell membrane.

Facilitated Diffusion: Diffusion of a polar substance w/ help from a carrier protein across the membrane; no energy.

Endocytosis: Process of taking material into the cell by making a pocket in the membrane.

Exocytosis: Spreading out of molecules from a region w/ high concentration to low one.

Transport Protein:

• carrier- changes shape to let substance thru

• channel- forms a channel to allow substance thru

Passive Transport: Transport of substances that doesn’t require energy.

Active Transport: Transport of substances that require energy (ATP.)

ATP: The energy “currency” of cells. Adenosine triphosphate.

With (down) the Concentration Gradient: Passive (diffuse) movement by substances (“going along with the flow.)

Against (up) the Concentration Gradient: Active movement from low to high concentration, requires energy.

Hypotonic:

• Around the cell: solution high, water low.

• In the cell: solution low, water high.

Hypertonic:

• Around the cell: solution low, water high

• In the cell: solution high, water low.

Isotonic:

• Around the cell: Solution and water are the same.

• In the cell: Solution and water are the same.