Describe structure and compositon of plasma membreane
Answers
The plasma membrane is composed of a phospholipid bilayer, which is two layers of phospholipids back-to-back. Phospholipids are lipids with a phosphate group attached to them. The phospholipids have one head and two tails. The head is polar and hydrophilic, or water-loving. The tails are nonpolar and hydrophobic, or water-fearing.Since water is the key component of living organisms, both inside and outside of the cell, this causes the phospholipids to line up in two layers with the heads pointing outward and the tails hidden in the middle. It basically looks like a phospholipid sandwich with the heads forming the bread and the tails forming the meat in the middle.Located all throughout the surface of the plasma membrane are cholesterol molecules. These molecules help stabilize the phospholipids and keep them in position. The plasma membrane is also dotted with proteins. Some of the proteins are peripheral proteins that only go halfway through the membrane, while others are integral proteins that go entirely through the membrane. These proteins serve as channels to allow the molecules to enter and leave the cell.
A cell membrane is a barrier that separates a cell from its surrounding environment.
* Function of Plasma Membrane
1. It separates the contents of the cell from its outside environment and it regulates what enters and exits the cell.
2. Plasma membrane plays a vital role in protecting the integrity of the interior of the cell by allowing only selected substances into the cell and keeping other substances out.
3. It also serves as a base of attachment for the cytoskeleton in some organisms and the cell wall in others. Thus the cell membrane supports the cell and helps in maintaining the shape of the cell.
4. The cell membrane is primarily composed of proteins and lipids. While lipids help to give membranes their flexibility and proteins monitor and maintain the cell's chemical climate and assist in the transfer of molecules across the membrane.
* Plasma Membrane Structure
`1. It is the boundary, which separates the living cell from their non-living surroundings.
2. It is a fluid mosaic of lids, proteins and carbohydrate.
3. It is lipid bilayer, which contains -two layers of phospholipids, phosphate head is polar, fatty acid tails non-polar (water fearing) and the proteins embedded in membrane.
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