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.
Define the major source of vitamin A? The major source of vitamin A, as you may be aware, is the carotenoid pigments which are synthesized by plants. Several carotenoid possess
Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4
Chambers of the Heart The heart is divided into two halves by a muscular wall or septum, the right heart and the left heart. The function of the right heart is to collect
During the course of a physiology laboratory, a student finds that her PR interval is 0.24 second. Concerned, she takes her own ECG again an hour later and sees an area of the ECG
What are natural active immunization and artificial active immunization? Natural active immunization is that in which a last natural infection induces the primary immune respon
If NAD+ is an electron acceptor that becomes NADH and the NADH then donates a proton to ATPase, shouldn't NADH now become NAD- since it lost it's proton but still has the electron?
what is the process of nitrogen fixation in soil by bacteria
Production of substances interfering with virus proliferation In some cases plants are known to synthesise chemicals that inhibit crucial functions of pathogens. This makes pl
Well Labaled DaiGram Of Cellular Endosperm
What is the vestibular system? How does it operate? The vestibular system is the part of the ear that participates in the control and regulation of the equilibrium of the body
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