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.
what are the classification of phylum platyhelminthes?
- Oogenesis involves the formation of haploid cells from an original diploid cell, called a primary oocyte, through meiosis. - The female ovaries contain the primary oocyte. The
Explan Ketogenic diet Ketogenic diet: It is occasionally used to facilitate the control of epilepsy. Here, the patient is initially fasted for 48 hours and thereafter,
Comparison between Regeneration and Embryonic Development By now you must have realized that the procedures of regeneration and embryonic development have several fundamental
Q. Describe Consciousness as the waking state? Consciousness as the waking state: consciousness is also referred to as the waking state as opposed for example to sleep. All
Most bacteria are anaerobic. If a bacterium were to produce the same amount of ATP within a minute as a cell extracted from your skeletal muscle, what would that bacterium have to
In which environments do bacteria live? Bacteria can be found in various environments throughout the planet. There are bacteria in the air, in fresh water, on the surface, in t
Explain Changes in Mental Development of Infants? There is evidently an increase in the brain size. There is a rapid increase in the number of brain cells in the first 5-6 mont
why is it necessary to classify living organisms ? what are the advantages of classifying organisms?
Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4
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