Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
CELL MEMBRANE
As discrete units of life all living cells are separated from each other and from their external environment by an extremely delicate (75 A to 100 a= 0.00075 to 0.001 thick ) covering membrane invisible under light microscope. The covering is called cell membrane, plasma membrane, cytoplasmic membrane or plasmalemma . Its presence was presumably visualized by Naegeli and Cramer(1855) and confirmed by E. Overton(1899) who believed that it was a double layer of lipid molecules .Since then, scientists have been making efforts to properly elucidate the molecular structure of this membrane. Gorter and gremdel (1925) postulated that it was a bimolecular lipid layer formed mainly of polar lipids with the double hydrophobic tails of their molecules in both layers directed towards the interior of the membrane, and their polar , hydrophilic heads, at the two surfaces of the membrane.
Danielli and Davson (1935) ascertained that the plasma membrane contains a good amount of globular proteins in addition to the lipids. They postulated a lipid protein bilaye r moderl of membrane structure with hydrated globular protein molecules adsorbed upon both exposed surfaces of the original biomolecular lipid layer, forming a protein lipid sandwich Later (1954) Danielli further proposed that there were places where lipid bilayer is perforated by pores lined by protein molecules, only polar solute molecules and ions can pass through these pores.
Using electron microscopy Robertson (1959) observed that the plasma membrane has a characteristic trilaminar appearance in a dark light dark or railway track pattern . Each dark line consists of a pleated sheet of protein on surface and sheet of polar heads of lipid molecules, while the light central line consists of a bilayer of nonpolar fatty acid of lipid molecules Robertson .called the trilaminar structure a unit membrane which is continuous with certain membranous structures present inside a cell.
Vesicular stomatitis Vesicular sto matitis virus be longs to the ge nus Vesiculovirus in fa mily Rhabdoviridae. The disease clinically resembles foot-and-mouth disease, but is
Q. What is the uncontrolled mitotic procedure that occurs as disease in pluricellular beings called? Uncontrolled mitotic cell division is known as neoplasia. Neoplasia the for
Homeostasis Homeostasis may be defined as the maintenance of constancy in the internal environment of the organism. This is essential for maintenance of life. Without homeost
Explain Theory of enzyme action L. Michaelis and k L. Menten developed a general theory of enzyme action and kinetics in 1913. According to this theory, we learnt that
Photosynthesis happens in algae, green plants and photosynthetic bacteria. Its part is to catch solar energy and use this to drive the synthesis of carbohydrate from water and carb
Adverse effects of lamivudine Because lamivudine is also active against hepatitis B virus (HBV), HIV-positive patients with chronic HBV infection may experience a flare of hep
A v i a n tuberculosis Tuberculosis in poultry has not remained a big threat in list of diseases due to commercialization of poultry business. It is a contagious chronic di
List a few shortcomings of native starches which make it unacceptable in certain food applications. Lack of free-flowing properties of water repellence of the starch granules,
Q. How is the circulatory system of reptiles characterized? What is the basic difference between the amphibian and the reptile heart? The circulatory system of beings of the cl
Tracheae - Respiratory Organs Tracheal respiration is characteristic of insects. Onychophorans, diplopods, arachnids, and chilopods as well use tracheal system for respiration
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd