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

Assessment - steps in nursing process, Assessment This includes the da...

Assessment This includes the data collection (nursing history and physical assessment), comparison of data with the normal, and analysis of the data gathered. Systematic an

Taxonomic key, I need help with making a taxonomic key

I need help with making a taxonomic key

Explain the consequences of malnutrition, Explain the Consequences of Malnu...

Explain the Consequences of Malnutrition? Malnutrition manifests itself in terms of illness and death in all age groups. Children, pregnant women, nursing mothers and elderly a

What structure replaces the graafian follicle, After ovulation:- (a) ...

After ovulation:- (a) what structure replaces the Graafian follicle (b) what hormone does it produce?   (a) After ovulation, the follicle is replaced by the cor

Verify where recombination happens along a chromosome, In a follow up to Al...

In a follow up to Alfred Sturtevant's studies on recombination in the fruit fly, Seymour Benzer used complementation studies of bacteriophage mutants to verify where recombination

TISSUES, WHY BLOOD IS CALLED FLUID CONNECTIVE TISSUE

WHY BLOOD IS CALLED FLUID CONNECTIVE TISSUE

A brief history of heart surgery, A brief history of heart surgery : The d...

A brief history of heart surgery : The dawn of Paediatric cardiac surgery was on August 26, 1938 when Robert, Gross, at the boston Children's Hospital, ligated ductus arteriosus

What is rh typing of mother & fetus hemolythemolytic disease, What is the R...

What is the Rh typing of the mother and of the fetus in the hemolytic disease of the newborn? In a hemolytic disease of the newborn the mother is Rh- and the fetus Rh+. In thes

Economic aspect of biodiversity, Q. Economic aspect of biodiversity? Bi...

Q. Economic aspect of biodiversity? Biodiversity serves as an income generating activity for countries around the world. Many people visit forests, beaches, mountains, grasslan

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