lunes, 5 de octubre de 2009

The Cell on its Environment (Page 80-85)

The Cell on its Environment (Page 80-85)
1.All cells are surrounded by a cell membrane that separates the cell from the outside environment.
2.The cell membrane is selectively permeable, wich means that some substances can pass through the membrane, while others cannot.
3.Cell must let in needed materials such as oxygen and food molecules. In contrast, waste materials must move out the cell, all must pass through cell membrane.

Substances that can move into and of a cell do by one of these materials:
Diffusion: Is the method by wich small molecules move across the cell membrane. Is the process by wich molecules move from an area of higher concentration to an area of lower concentration.

Osmosis: Is the diffusion on water molecules through a selectively permeable membrane. Because cell can´t function properly without adequate water, many of the cell process depends on osmosis.

Active and Passive Transport: Is the movement of materials through a cell membrane using cellular energy. Active transport requires the cell to use its own energy, while passive transport does not.

By Mauricio Pérez Chávez
M13

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