![]() ![]() ![]() The cookie is used to store the user consent for the cookies in the category "Analytics". This cookie is set by GDPR Cookie Consent plugin. These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly. Principles of Inheritance and Variation.New Questions and Answers and Forum Categories This cell fusion can be induced by agents called fusogen (e.g., Sendai virus, polyethyleneglycol, electric shock etc.) (Fig. (b) Frey and Edidin (1970) experimentally demonstrated the fluid nature of plasma membrane b) fusion of a mouse cell with a human cell to yield a hybrid cell called heterokaryon or cybrids. (a) Branton (1968) conformed the mosaic nature of proteins by studying freeze-fracture electron microscopy of the plasma membrane that revealed randomly distributed pumps and depressions (Fig. They act as cell surface markers, receptors, blood grouping etc. The oligosaccharides gives a negative charge to outer surface. The carbohydrate coat present on the E-face of plasma membrane constitute glycocalyx or cell coat. They are bound to both proteins and phospholipids producing glycoproteins and glycolipids respectively. (iv) The exoplasmic face (E-face) of the cell membrane often possesses carbohydrate chains or oligosaccharides. Membrane proteins have various roles-mechanical, transport, enzymatic etc. Nearly all known integral proteins span the lipid bilayer, while peripheral proteins are superficially attached by electrostatic and hydrogen bond interactions. The Membrane proteins are two types: integral or intrinsic (~ 70%) and peripheral or extrinsic (-30%). All lipids are symbolically represented with a polar head and two fatty acid tails. Sterols found in the membrane may be cholesterol (in animals), stigmasterol, β-sterol (in plants) and ergosterol (in microbes). The glycolipids may be cerebroside or ganglioside. phophatidylionositol, phosphotidylserine etc.). phosphatidylcholine, phosphatidylethalamine and spingomyelin) and the rest phospholipid s are acidic or negatively charged (e.g. Majority (80%) of the phospholipids are neutral (e.g. The membrane lipids of plasma membrane are of 3 major types:Īll of them are amphipathic or amphiatic molecules because they possess both hydrophilic (polar) and hydrophobic (non-polar) ends. The lipids and proteins are held together by non-covalent interactions. The carbohydrates found in the form of glycoproteins or glycolipids and restricted only to the outer surface of plasma membrane. The plasma membrane and the intracellular membranes together called as biological membranes of bio-membranes.Ĭhemically plasma membrane is a molecular assembly of lipids (20- 40%), proteins (60-75%) and carbohydrates (1-5%). In addition to Plasma membrane, eukaryotic cells contain intracellular membrane surrounding, the vacuole and organelles. But prokaryotes and plant cells generally have an additional cell wall outside the plasma membrane. It is the outermost boundary of all living cells. ![]()
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