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.
Is the effect of genetic drift likely to be the same in pop 1 and pop 2? How are genetic drift and pop size related? when there is strong selection against the homozygous recessive
Peri operative Myocardial Infarction : Peri operative Myocardial Infarction is diagnosed by the appearance of fresh Q waves. Non-Q, myocardial infarction is suspected when there
Oligomeric enzymes Oligomeric proteins consist of two or more polypeptide chains, which are usually linked to each other by non-covalent interactions and never by peptide bonds
Which of the following is true for a toe corticospinal interneuron that produces action potentials during movements of the big toe of the left foot? A. A portion of its axon is
Q. Define Low - density lipoprotein? Ans. LDL is the major cholesterol-rich lipoprotein carrying approximately 70 per cent of plasma cholesterol. It serves to transport ch
Which of the following is true for a motor cortex corticospinal interneuron A that produces action potentials during movements of the big toe of the right foot in right-handed Pati
Explain amino acid composition In terms of amino acid composition, high radiation doses such as those required for sterilization (e.g. 25-27Kgy), do not change the content of c
Define Factors that Affecting the BMR? Basal metabolic rate, we know, is the largest component of the daily energy demand representing 45 to 70 percent of daily total energy ex
Define about the Carbohydrates - nutritional biochemistry? Carbohydrates, you should observe by now, are made up of carbon, hydrogen and oxygen only with hydrogen and oxygen at
Day-Neutral Plants Besides SDP and LDP, those plants that flower irrespective of the length of light are called day-neutral plants. For these there is no specific requirement
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