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

What is the phellogen? what its function, What is the phellogen? What its f...

What is the phellogen? What its function? The Phellogen also called as cork cambium is the meristematic plant tissue responsible for the formation of the periderm (the covering

Mouth examination of new born, Mouth Inspect and palpate the lips, ...

Mouth Inspect and palpate the lips, gums, tongue, palate and oropharynx. Rule out cleft lip and palate, size of chin if small and receding it  shows micrognathia ind

Conduction system - heart, In this unit, you have learnt that heart is a mu...

In this unit, you have learnt that heart is a muscular organ situated in thorax covering with pericardium and consist of four chambers i.e. right atrium, left atrium, right ventric

What similarities do birds and reptiles share, What similarities do birds a...

What similarities do birds and reptiles share regarding external coverage, reproduction and excretion? Regarding external coverage, birds are same to reptiles as they present

What are the three main types of viral hepatitis, Q. What are the three mai...

Q. What are the three main types of viral hepatitis? There are various types of viral hepatitis. The most vital epidemiologically are hepatitis A, hepatitis B and hepatitis C.

Quaternary structure of protein, Quaternary Structure (4 o Structure)....

Quaternary Structure (4 o Structure). Globular in structure. When two or more than two molecules of protein of tertiary structure are connected to each other through

Draw on knowledge of electron distribution, While waiting at an airport , n...

While waiting at an airport , nail Campbell once overheard this claim, its paranoid and ignorant to worry about industry or agriculture contaminating the environment with chemical

Metabolism, METABOLISM  - Word given by Shwann . It includes bio-ch...

METABOLISM  - Word given by Shwann . It includes bio-chemical reactions occur in body may be constructive or destructive. It includes -                         Anabo

Unit membrane model, Unit Membrane Model Lamellar model was supported ...

Unit Membrane Model Lamellar model was supported by Robertson. According to Robertson - All biomembrane have similar structure (like PM), on the basis of this observati

Hutchinson phyletic dieta, hi there,i would like u to help me with understa...

hi there,i would like u to help me with understanding Hutchinson phyletic dieta

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