Questions about the cell membrane

The cell membrane is a biological membrane that separates the interior of all cells from the outside environment.[1] The cell membrane is selectively-permeable to ions and organic molecules and controls the movement of substances in and out of cells.[2] It consists of the phospholipid bilayer with embedded proteins. Cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity and cell signaling and serve as the attachment surface for the extracellular glycocalyx and cell wall and intracellular cytoskeleton

Structure

Fluid mosaic model

According to the fluid mosaic model of S. J. Singer and Garth Nicolson 1972, the biological membranes can be considered as a two-dimensional liquid where all lipid and protein molecules diffuse more or less easily.[3] This picture may be valid in the space scale of 10 nm. However, the plasma membranes contain different structures or domains that can be classified as: (a) protein-protein complexes; (b) lipid rafts, and (c) pickets and fences formed by the actin-based cytoskeleton.


Function

The cell membrane surrounds the protoplasm of a cell and, in animal cells, physically separates the intracellular components from the extracellular environment. Fungi, bacteria and plants also have the cell wall which provides a mechanical support for the cell and precludes passage of the larger molecules. The cell membrane also plays a role in anchoring the cytoskeleton to provide shape to the cell, and in attaching to the extracellular matrix and other cells to help group cells together to form tissues.

The barrier is differentially permeable and able to regulate what enters and exits the cell, thus facilitating the transport of materials needed for survival. The movement of substances across the membrane can be either passive, occurring without the input of cellular energy, or active, requiring the cell to expend energy in moving it. The membrane also maintains the cell potential.The cell membrane works as a selective filter that allows only certain things to come inside or go outside the cell, it is important in maintaining a homeostatic environment in the cell to keep us healthy and alive

and abt transport...
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http://www.college-cram.com/study/biolog…

The cell membrane has two proposed models; the fluid mosaic model and the Danielli-Ravson Hypothesis. (not so sure about the spelling on this one though, you should check it out.{Biological science by PJ TAYLOR}). I will type you a more detailed version in 2 days. stay locked.