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.
Absence of vesicular glands In some bulls the vesicular glands are either absent or hypoplastic also sometimes accompanied by poorly developed ampullae. A characteristic sympt
Micrographia is abnormally small, cramped handwriting and/or the progression to continually smaller handwriting. This is one of the symptoms of Parkinson''s disease.
Protozoans Prokaryotes represent only a few thousand of the estimated 2 million species of living beings known on the earth today. The rest are mostly eukaryotes that form the
State the Principle of Adaptation The first principle is that the central goal of assessment is to promote the adaptation of the child, rather than simply to document the prese
If the condition or the post disease as a result of intraradicular infection----> treated conventionally via apex " non-surgical ", ---->Here we have 2 options either coronal
occurrence of e.coli 0157:H7 on vegetables
Mechanism of Phloem Transport The efficiency and magnitude of translocation of food material are evident from the annual yields of various crops and fruits. Now, the question
mitosis define
Define Water as a temperature regulator? Water plays an important role in the distribution of heat throughout the body and the regulation of body temperature. Heat is generate
Q. How many are the well-known amino acids that form proteins in living beings? There are twenty different known amino acids that form proteins related to the genetic code of t
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