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.
Explain Trifluridine (Viroptic) Trifluridine is a nucleoside analog active against herpes viruses, including acyclovir-resistant strains. Marketed in an ophthalmic preparatio
In general what is the cause of the aneuploidies? In general the aneuploidies are caused by impaired assortment of chromosomes during meiosis. For instance, when the homologous
Dr. Herbert discovers a cell and he is convinced it is a plant cell. However, as a student of his genetics class, you do not agree with him. You do not believe in microscopy and ph
Q. How is the ovulation date estimated with the control of the woman's body temperature? One method to estimate the exact ovulation day is daily control of the body temperature
ARE VIRUSES CELLULAR ORGANISMS?
cutaneous respiration in musquito
Define Dietary modifications in the diet of the elderly? Loss of teeth due to increased decay of teeth and gums is common in aged person. Fitting dentures may also make chewin
Q. How do populations of predators and prey vary in predatism? Whenever a predator population enhance at the first moment the prey population tends to reduce. At a second momen
Particulates: These are suspended droplets, solid particles or mixture of two. So all the atmospheric substances that are not gases are called particulates. A number of term
i wanted to make assigment ..
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