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 Proteins as regulators of water balance? As substrates and solutes are transferred or exchanged across membranes, water has a tendency to follow to maintain equal osmoti
Sludge treatment and disposal: most of the suspended solids and some of the dissolved organic solids, in a converted form, are separated from the main flow of the, in the form of
Why can it be said that the enzymatic action is highly specific? The enzymatic action is highly specific because only exact substrates of one enzyme bind to the activation cent
Q. Symptoms of Angina Pectoris? The pain of angina is usually over the center of the chest (below the sternum) but can be felt from epigastrum to the jaw and arms. It is brough
Define Total Body Potassium (TBK)? Potassium in the body is an index of body's total cell mass. A gamma counter measures the amount of a type of potassium which is assumed t
Would you expect the muscle fibers of the tongue to be striated or smooth? What about the muscle of the diaphragm/ Explain your answer.
Factors affects Oxygen Dissociation Curve -Organic Phosphate The presence of organic phosphates in the red blood cells helps to explain many peculiarities of the oxygen dissoc
How does the embryo turn from gastrula into neurula? How is the neural tube formed? What is the embryonic origin of the nervous system in vertebrates? The neurula stage is divi
Q. What do you mean by Wound closure? Generally the incisions designed for minimal exposure such as the H - shaped incision, do not require suturing, as the abutment and the tr
What are some things that have algae in them? Yeast is considered Algae.
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