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.
Why is glucose such a good source of energy for bacteria? 1) Glucose contains six oxygen atoms, which can be used for oxidative phosphorylation and the generation of many ATP molec
Explain Procedure for Detection of Metanil Yellow? Carry out the exercise following the steps enumerated herewith. 1. Suspend the food sample in water and shake vigorously.
Q. How are the triglycerides made? Triglycerides, oils or fats, are made of one molecule of glycerol bound to three molecules of fatty acids. Hydroxyls of each one of the three
High blood pressure makes your heart work harder and, over time, can damage blood vessels throughout your body. If the blood vessels in your kidneys are damaged, they may stop remo
How Water content Influence the RS content? The yield of RS formed in heat-moisture treatment is closely related to water content, which may be an inherent component of food or
Q. What is the morphological characteristic that evolutionarily approximates the beings of the phylum Annelida to arthropods? The metameric feature that is the body segmentatio
Let us learn about the factors that affect metabolism: 1) More energy is required when muscular work is carried out. 2) The larger the surface area of the body, more heat is
What are the apical meristems? Which kind of plant growth does this meristem promote? The Apical meristems are those primary meristems found in the apex of the stem as well as
Explain Technical factors influencing food production? Improvement in technology has a significant impact on productivity. Improvements may occur in seed production, fertilizer
disadvantages of protozoa in points
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