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

Explain about the pregnancy and obesity, Explain the Pregnancy and Obesity?...

Explain the Pregnancy and Obesity? Obesity is associated with increased risk for gestational diabetes, hypertension, pre- eclampsia, perinatal mortality and the need for induce

Animal diversity, why obelia is of special interest in zoology

why obelia is of special interest in zoology

Things to do during a cyclone, (a)   For any individual :               ...

(a)   For any individual :                  ·          We should check house, doors and windows and have them repaired whenever necessary.                  ·          We shou

Comparison between regeneration and embryonic development, Comparison betwe...

Comparison between Regeneration and Embryonic Development By now you must have realized that the procedures of regeneration and embryonic development have several fundamental

Extracellular signals, extracellular signals and their characteristics

extracellular signals and their characteristics

What is polysaccharides, What is Polysaccharides? Polysaccharides:  M...

What is Polysaccharides? Polysaccharides:  Many monosaccharide subunits can be joined to form long, complex polysaccharide molecules. These complex sugars are often used to s

How the rhizopus reproduce?, How the Rhizopus reproduce? Rhizopus usual...

How the Rhizopus reproduce? Rhizopus usually reproduce asexually, but under unfavourable conditions, sexual reproduction (isogamous) occur resulting in formation of zygospores

Explain difference between an ecological niche and a habitat, What is the d...

What is the difference between an ecological niche and a habitat? An ecological place is a set of peculiar activities, resources and strategies that a species explores to repro

Sea Lampreys, #questiHow do the non parasitic lampreys interact with other ...

#questiHow do the non parasitic lampreys interact with other members of their ecosystem in comparison to their parasitic cousinson..

Non migrainous vascular headaches, Non Migrainous Vascular Headaches Th...

Non Migrainous Vascular Headaches This headache associated with dilation of the cranial arteries and can be induced by a wide variety of diseases and conditions. The most commo

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