Fluid mosaic model, Biology

Assignment Help:

FLUID MOSAIC MODEL

  • Proposed by Nicholson and Singer (1972)
  • Proteins and lipids are arranged in a mosaic fashion.
  • Lipids and proteins are in a semi fluid structure. Fluidity of P.M. is due to phospholipids. Phospholipids of P.M. are rich in unsaturated fatty acid that's why these occur as liquid.
  • Main component of cell membrane are phospholipids because these form structural frame work of cell membrane.
  • In lipid part, plasma membrane also contains cholesterol. Cholesterol is mainly found in inner half of the membrane. Cholesterol molecules are more rigid than the phospholipids and therefore, presence of cholesterol confers stability on eucaryotic membranes.
  • Procaryotic cell membrane lacks cholesterol. However, in some bacteria pentacyclic sterole like molecules termed as hopanoids are present. Hopanoids stabilize the bacterial membrane.

714_fluid mosaic model.png

P.M. may be termed as "protein icebergs in a sea of phospholipids". or Gulab jamun (protiens) in a concentrated solution of sugar (phospholipids).

Two types of proteins are found in P.M.

(i) Integral or intrinsic proteins - Tightly held to phospholipid. These also cover minute pores. These are 70% of the total protein. These proteins may traverse the complete thickness of P.M. Intrinsic protein form channels which provide a rapid passage to water soluble materials across the P.M.

Some intrinsic protein molecules extend through the membrane as single helix on both the sides. These called transmembrane proteins.

(ii) Peripheral or extrinsic proteins - 20-30% of total proteins.

  1. Superficially arranged on either side of P.M. and can be separated easily. These proteins have enzymatic activity and commonly called permeases. Extrinsic proteins can freely move in P.M. and regulate it's permeability. Extrinsic protiens function as carriers for the transport of material.
  2. "Spectrins" are helical extrinsic protein which found an cytosolic face of membrane attached to intrinsic proteins.
  3. Spectrins are part of cytoskeleton.
  4. Carbohydrates (oligosaccharides) in plasma membrane occurs only on its outer surface in form of Glycoproteins, glycolipids, lectins (antibodies, antigens) , sialic acid etc. So the two face of plasma membrane are asymmetrical.
  5. Glycoproteins and glycolipids help in cell recognition. Cells of same organism or of same tissue recognize each other with the help of glycoprotiens and glycolipids. Best example of cell recognition is fertilization where sperm and egg recognize each other.
  6. Beside all these compounds, P.M. have approximately 30 types of enzymes ( ATPases)

Related Discussions:- Fluid mosaic model

Show the process of healing abutment, Q. Show the process of Healing abutme...

Q. Show the process of Healing abutment? Healing abutments are therefore not considered ideal. It is for this reason that the definitive abutment, selected at first stage surge

Effect of sodium chloride concentration on water activity, Solutes and ions...

Solutes and ions tie up water in solution. Solutes lower aw and this reduction in aw depends on the total concentration of dissolved molecules and ions. Since these bind to water m

Determine the important rule of insulin syringes, Insulin Syringes Syri...

Insulin Syringes Syringes for insulin are designed for standard U-100 insulin. 1 ml of insulin has 100 standard units of insulin. Syringe has markings in insulin units it helps

Explain rabies, Rabies  Rabies is highly prevalent in Africa, India, As...

Rabies  Rabies is highly prevalent in Africa, India, Asia and parts of Latin America, but the risk to travelers is low. Pre-exposure immunizationagainst rabies is recommended f

Explain adverse effects of imiquimod, Adverse Effects of Imiquimod Appl...

Adverse Effects of Imiquimod Application site reactions (irritation, pruritus, flaking, erosion) are generally mild to moderate in intensity and resolve within 2 weeks of cessa

Acute phase reactants, ESR and CRP are elevated in almost all patients of a...

ESR and CRP are elevated in almost all patients of arthritis and carditis and rarely in patients with chorea. ESR should be repeated periodically as it is useful in following the c

Explain about the lipoproteins, Explain about the Lipoproteins? These a...

Explain about the Lipoproteins? These are the Multicomponent complexes of lipids and proteins that form distinct molecular aggregates. They contain polar and neutral lipids, ch

Define quantitative procedures in carbohydrates, Define Quantitative Proced...

Define Quantitative Procedures in Carbohydrates? You have learnt how to identify some individual monosaccharides, disaccharides and polysaccharides. However, if we were asked t

What is the meaning of visuoperceptive disorders, What is the meaning of Vi...

What is the meaning of Visuoperceptive disorders It relates to the way in which brain damage impairs people's ability to adapt to the visual world and the concepts used to trea

Categories of value of biodiversity, Q. Categories of value of biodiversity...

Q. Categories of value of biodiversity? The value of biodiversity is often divided into two main categories: · UTILITARIAN (also known as instrumental, extrinsic, or use) v

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd