Chapter 3 - Cells Exchange Materials

The cells are maintained at a constant temperature and the concentration of fluids around the cell is kept constant.

The maintenance of a relatively constant internal environment despite fluctuations in the external environment.

Oxygen + Glucose = Carbon Dioxide + Water + Waste O2 + C6H12O6 = CO2 + H2O

Lipids and Proteins

A passive process occurs without the use of the cell’s energy which comes from respiration and an Active process requires the use of the cell’s energy.

• Passive Process * Resulting from the random movement of ions and molecules.

• Active Process * Where materials are moved in membrane-bound sacs.

• May be Passive or Active * Requires special proteins in the cell membrane to bind to an ion or molecule and help it move across the membrane.

The greater the difference in concentration the “steeper” the diffusion gradient and the faster the diffusion will occur.

Osmosis is a special type of diffusion, it is the diffusion of a solvent through a semi-permeable membrane.

It is a process carried out through the cell membrane by carrier proteins when a substance is too big to be transported through the cell membrane through simple diffusion.

Active transport is the movement of substances across the membrane against the concentration gradient using cellular energy.

An active transport which materials move into or out of the cell enclosed as vesicles.

The pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis, often used to express the concentration of the solution.