Minggu, 27 Februari 2011


Alit Adi Sanjaya

Standard Competency:    
1.     To understand structure and function of cell as the smallest structures capable of basic life processes

Basic Competency:
1.3. To compare mechanism of membrane transport ( diffusion, osmosis, active  transport, endocytosis and exocytosis )
Indicator :
1.    To explain characteristic diffusion and osmosis transport
2.    To draw cell that experience plasmolyzed
3.    To explain plasmolyzed process

Membrane transport

 Passive transport is  the spontaneous movement of a substance from a region of greater concentration to a region of lesser concentration. The difference between the concentration of a substance in two different areas is known as a concentration gradient. The examples are diffusion and osmosis
ü  Diffusion is the flow of energy or matter from a higher concentration to a lower concentration, resulting in a homogeneous distribution. If one end of a rod is heated or electrically charged, the heat or electricity will diffuse from the hot or charged portion to the cool or uncharged portion. Not all substance or molecules can pass through cell membrane by means of diffusion, for example glucose and amino acid. Both can pass through cell membrane by means of bounded or facilitated diffusion. By this way, glucose and amino acids will bind to permease. Permease is a molecule of transporter protein that assists transportation through cell membrane.

ü  Osmosis is the flow of water molecule from hypotonic solution ( high water concentration, low dissolve substance ) to the hypertonic solution (low water concentration, high dissolve substance ) through semipermeable membrane without energy. An example of osmosis is transfer of sugar solution in scaled glass pipe layered with cellophane (as semipermeable membrane) in container filled in with clear water.

ü  Plasmolyzed is liberated of plasm membrane because water in cytoplasm go out. When plant cell in hypertinic condition so a water in cell will go out from cell and make wrinkle cell. 

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