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

Radioactive labelling, Radioactive Labelling Radioactive labelling me...

Radioactive Labelling Radioactive labelling method has been effectively applied on the chick blastoderm. The method includes labelling one embryo (donor) and grafting a part

Urine analysis, Urine analysis - microhematuria with or without proteinuria...

Urine analysis - microhematuria with or without proteinuria may be seen. ECG - All patients with suspected IE should have baseline and follow up ECG which may reveal conduction

What is the result of post myocardial infarction ventricular, What is the r...

What is the result of Post Myocardial Infarction Ventricular ? Results: Hospital mortality may be as high as 30 per cent. This depends on the extent of infarction and- pre-op

Explain about the waist to hip ratio (whr), Explain about the Waist to Hip ...

Explain about the Waist to Hip Ratio (WHR)? Two individuals who have the same BMI and the same total body fat may have different abdominal fat mass. Abdominal fat accumulation

Describe the frequency of low-risk coronary patients, Describe the Frequenc...

Describe the Frequency of low-risk coronary patients? For many low-risk coronary patients, particularly those following myocardial revascularization procedures, rehabilitation

Define about the term indicators, Define about the term Indicators? The...

Define about the term Indicators? The easiest way to determine when the reaction is complete is by using indicators. An indicator is a compound that has a physical property (us

Carbonization process, When coal is heated strongly in absence of air, it f...

When coal is heated strongly in absence of air, it forms a strong, porous, dense and coherent mass known as coke. This process of conversion of coal into coke is called carbonzatio

Describe austin flint murmur in heart dieases, Describe Austin Flint Murmur...

Describe Austin Flint Murmur in heart dieases? The AR jet may impinge on the undersurface of the anterior leaflet of the mitral valve and push it up, thus creating a relative M

How can the hypothesis that asserts that chloroplasts, How can the hypothes...

How can the hypothesis that asserts that chloroplasts as well as mitochondria were primitive prokaryotes that associated in mutualism with primitive anaerobic eukaryotic cells be c

Explain what is fern allies - lycopophyta, Explain what is Fern Allies - Ly...

Explain what is Fern Allies - Lycopophyta ? Fern allies are those groups of vascular (with conducting vessels) plants that have close ties to the ferns. Sometimes they are refe

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