The Effect Of Selective Permeability On The Cell

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INTRODUCTION: If a cell is to perform its functions it must maintain a steady state in the midst of an ever changing environment. This steadiness is maintained by the regulation of movement of materials into and out of the cell. To achieve this control, cells are bounded by a delicate membrane that differentiates between different substances, slowing down the movement of some while allowing others to pass through. The membrane is said to be differentially permeable since not all substances penetrate equally well. Selective permeability is a characteristic of healthy, intact cells. When a cell is seriously damaged, the membrane becomes permeable to virtually to everything and substances can move freely in and out of the cell. (Marieb 2013)…show more content…
(Marieb 2013) Osmosis, is a special kind of diffusion, is defined as the diffusion of water through a semi-permeable membrane from a higher concentration to that of a lower concentration. The concentration of water is inversely related to the concentration of solutes. If the water can diffuse across the membrane, both water and solutes will move down their concentration gradients through the membrane. (Marieb 2012) There are three terms used to describe the concentrations of solute particles of different solutions: Hypotonic- When compared to another solution of different concentration, the solution contains the lower concentration of solute particles. Water moves across a semi-permeable membrane out of a hypotonic solution. Hypertonic- When compared to another solution of different concentration, the solution that contains the higher concentration of solute particles. Water moves across a semi-permeable membrane into a hypertonic solution. Isotonic-Having the same concentration of solute particles as another solution. There is no net flow of water across the membrane. In animal cells, the movement of water is affected by the relative solute concentration of the plasma membrane. As water moves out of the cell, the cell shrink and if water moves into the cell, the cell swells and may even burst. PURPOSE: The objective of this
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