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

Sugarcane, what the by products of sugarcane

what the by products of sugarcane

Non-extractive use values, Some activities that make use of biological reso...

Some activities that make use of biological resources, without involving their extraction or destruction, denote non- extractive use of biological resources. This includes ecotouri

Pattern of limb development, Pattern of Limb Development The first vi...

Pattern of Limb Development The first visible sign of limb development is the appearance of ridge or thickening on each lateral side of the embryo of amniotes. The ridge call

Echocardiography, E c h o c a r d i og r a...

E c h o c a r d i og r ap h y : It is an exceptionally useful technique for diagnosing cardiovascular diseases, particularly in small an

Explain stavudine, Explain Stavudine It can be given either in initial ...

Explain Stavudine It can be given either in initial combination therapy or after failure of regimens containing other NRTIs. Cross-resistance with zidovudine is frequent, ho

Polyarthritis, It is the most common (occurring in 75 per cent cases of ARF...

It is the most common (occurring in 75 per cent cases of ARF) manifestation of ARF. It involves large joints, it is typically fleeting in character shifting from one large joint t

Genetics, name a disorder of human blood that is caused by mutation

name a disorder of human blood that is caused by mutation

What are phenotypical & genotypical proportions in f1 & f2, According to th...

According to the Mendel's second law, in the crossing between homozygous individuals concerning two pairs of nonlinked alleles, AABB x aaBB, what are the phenotypical and genotypic

What is the kind of digestive system of echinoderms, Q What is the kind of ...

Q What is the kind of digestive system of echinoderms? Echinoderms present a complete digestive system with anus and mouth. Q. Do sea urchins have teeth? Sea urchins ha

Where do most allergic reactions occur, Most of them happen on mucous membr...

Most of them happen on mucous membrane. Allergens enter the body by the process of inhalation or ingestion.

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