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.
NONSTRIATED (= SMOOTH) MUSCLES - Non-striated muscles are found in the posterior part of oesophagus, stomach, intestine, lungs, urinogenital tract, urinary bladder, blood ve
State the Definition of respiration Respiration is an act of breathing. (i.e. rise and fall of the chest). Respiration hastwo parts i.e. inhalation and exhalation. When we bre
ENDOPLASMIC RETICULUM It is also known as Endoskeleton of the cell, Endomembranous system of the cell. Garnier (1897) first observed them and called Ergastoplasm. E.R.
Other Complications of Prosthetic Valves : One of the dreaded complications of mitral valve replacement is ventricular rupture. It is difficult to manage and so it is better avoi
Source of Energy and Protein The by-products obtained from grain processing (brans), oil seed processing (oil meals) and pulses processing industries are the major and importan
When constructing phylogenies using maximum likelihood methods, you assume?
Define Surgery Process for Head and Neck Tumor? Treatment mostly involves combination of surgery and radiation. Chemotherapy is also used in some cases, we will learn about the
Q. Describe Sensory Receptors? Receptor organs can detect external or internal stimuli. They can be classified according to the stimulus to which they respond: • Photorecep
Nerve to Mylohyoid Motor branch of inferior dental nerve which descends in a groove on the medial surface of the mandibular ramus. Surgical intervention in this area may lead
why are the microspores in groups of four?
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