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.
Epidemiological Theory - Accident Causation Epidemiological theory of accident causation considers industrial hygiene that concerns environmental issues and may result in sick
Define Urinary Excretion Test - Thiamin Status? The urinary excretion of thiamin is an index of recent dietary intake of the vitamin. Hence, determination of thiamin in urine s
Explain the Cardiac Cycle of human body? The different stages of a heart pumping cycle are referred to as follows: contraction of the ventricles is called systole, and relaxati
Distinct types of proteins Two distinct types of proteins are known: fibrous and globular proteins. Fibrous proteins are insoluble in water and are physically tough, which
Effect on Microbial Growth and Activity Bacteria require higher aw for growth than fungi. Gram-negative bacteria have higher requirements than gram positives. Most spoilage ba
Q. Define the Organization Levels of Life? Ans. The cell is the basic unit of life - the smallest unit that can carry on all the processes of life. Organisms that consist of a
defitionce of vitamin d
State about polyploid cells During development cells of certain tissues like the salivary gland and liver produce extraordinary amounts of selected proteins. This is often achi
Starch Retrogradation The starch paste or solution obtained after the gelatinisation is not stable and generally produces a viscoelastic, firm and rigid gel. Structural transf
Define the patient care related to neurological disorder? A few additional points related to the patient care that need to be kept in mind include paying attention to the patie
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