BIOL 2130 Lecture Notes - Lecture 9: Osmosis, Lysosome, Phagocytosis

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28 Mar 2017
Cell Physiology
Cells have the ability to:
oDigest food
oDispose of wastes
oRespond to a stimulus
Solution- homogeneous mixture of two or more components
oSolvent- dissolving medium; typically water in the body
oSolutes- components in smaller quantities within a solution
Membrane Transport
The plasms membrane is a selectively permeable barrier
oSome materials can pass through while others are excluded
oFor example:
Nutrients can enter the cell
Undesirable substances are kept out
Two basic methods of transport
oPassive process
No energy (ATP) is required
oActive process
Cell must provide metabolic energy(ATP)
Passive Processes
oParticles tend to distribute themselves evenly within a solution
oDriving force is the kinetic energy (energy of motion) that’s causes the molecules
to move about randomly
oMolecule movement is from high concentration to low concentration, or down a
concentration gradient
oSize of molecule and temperature affects the speed of diffusion
The smaller the molecule, the faster the rate of diffusion
The warmer the molecule, the faster the rate of diffusion
Molecules will move by diffusion if any of the following applies:
oThe molecules are small enough to pass through the membrane’s pores
(channels formed by membrane proteins)
oThe molecules are lipid-soluble
oThe molecules are assisted by a membrane carrier
Types of diffusion
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