Plasma Membrane Essay

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Plasma Membrane: The plasma membrane is a super molecular structure that regulates transport across the cell which is essenitial to a cell’s existance and is currently represented by the fluid mosaic model. The reasosn why it is called the Fluid mosaic Model is because the plasma membrane is selectivley permeable. In 1925 scientist found out that the memebrane contains a phospholipid bilayer that is amphipathic, which means the bilayer contains a portion that is polar( hydrophilic) and a portion that is nonpolar( hydrophobic). The plasma membrane is selectivly permeable, meaning that small molecules and hydrophobic moelcules are able to easily pass through the membrane however hyrdrophilic molecules have more trouble passing through because the middle of the plasma membrane is hydrophobic. Along with the phospholipids, the membrane also contains cholesterol particles that also make it harder for bigger molecules to inter the cell. Certain integral proteins that are embeded through out the plasma membrane and even into the hydrophoic core of the bilayer help regulate bigger molecules that have trouble passing through the membrane.There are also peripheral proteins that no embedded ito the lipis bilayer but simply lay on the membrane surface.Carbohydrates are present on the extracellular end of the plasma membrane and contribute to cell to cell recognition. Sometimes carbohydrates bond with lipids to produce a glycolipid or covalently bond with proteins to prodeuce a glycoprotien that also help in distinguishing cells from one to another. The old version of the Fluid Mosaic Model is called the davson model or the “Sandwhich Model”. This model not only failed to recognize that the membrane is amphipathic but also it never accounted for the active and passive transport system. Through the plasma membrance water is able to facilitate through the cell using

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