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

Define the patient care related to neurological disorder, Define the patien...

Define the patient care related to neurological disorder? A few additional points related to the patient care that need to be kept in mind include paying attention to the patie

Bluetongue, B l u e t on g u e Bluetongue (BT) is a non-contagi...

B l u e t on g u e Bluetongue (BT) is a non-contagious and arboviral disease of both domestic and wild ruminants. The disease is enzootic in areas where reservoirs (cat

Describe excretory system of annelids, Q. How be able to the excretory syst...

Q. How be able to the excretory system of annelids be described? In each segment (metamere) of the being a pair of complete excretory structures known as metanephridium exists.

The outside of the neuron to the inside, Which of the following require ATP...

Which of the following require ATP? The movement of potassium from the outside of the neuron to the inside? The movement of sodium into the neuron through a chemically gated

How does the heart impel the blood, Q. How does the heart impel the blood? ...

Q. How does the heart impel the blood? The heart is a muscular organ that contains chambers right ventricle and right atrium right ventricle and and left atrium through which b

What is the name of the sea anemones and larva of corals, Q. What is the na...

Q. What is the name of the sea anemones and larva of corals? What is the biological importance of that larval stage? Sexual reproduction in sea anemones and corals have a larva

Plant cell wall react when it is placed in hypotonic medium, How does the p...

How does the plant cell wall react when it is placed under hypotonic medium? Ans) The plant cell wall (the covering of the cell outside to the cell membrane) is made of cellulos

Ecosystem degradation and wildlife, Ecosystem Degradation and Wildlife ...

Ecosystem Degradation and Wildlife Man is an animal with ecological requirements just like any other animal. It constantly needs a source of energy and.minera1 nutrients for i

Sun, wath is sun

wath is sun

What is constrictive pericarditis, Q. What is Constrictive pericarditis? ...

Q. What is Constrictive pericarditis? Constrictive pericarditis is the sequelae of chronic fibrosis and thickening of the pericardium as a result of chronic inflammation. E

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