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 thoracic, Thoracic (non-cardiac) Antibiotic prophylaxis is give...

Thoracic (non-cardiac) Antibiotic prophylaxis is given routinely in thoracic surgery, but sup- porting data are sparse. In one study, a single preoperative dose of cefazolin be

Define the role of riboflavin in antioxidant activity, Define the role of r...

Define the role of riboflavin in Antioxidant Activity? Flavoproteins also have powerful antioxidant activity from their role as precursors to FMN and FAD. Among the FAD-requiri

Class of crustacea - branchiopoda, Class of Crustacea - Branchiopoda ...

Class of Crustacea - Branchiopoda These are small fresh water crustaceans. The trunk appendages are flattened and leaf like and are helpful for locomotion also respiration he

Emergence of contemporary biology, EMERGENC E OF CONTEMPORARY BIOLOGY - ...

EMERGENC E OF CONTEMPORARY BIOLOGY - 1 .       Aristotle (384-322BC) - Greek Classified animal species and arranged them in hierarchies. Formulated 'Great chain of

Bees, is there a difference between the giant asiatic bees apis dorsata and...

is there a difference between the giant asiatic bees apis dorsata and Philippine giant bees apis breviligula

What are the examples of homeostasis, What are the examples of homeostasis?...

What are the examples of homeostasis? Regulation of body temperature, control of blood glucose levels, the regulation of salt and water balance are the example of homeostasis

The neural impulse is transmitted along the axon, What is the mechanism by ...

What is the mechanism by which the neural impulse is transmitted along the axon? The neural impulse is transmitted with the neuronal membrane through depolarization of consecu

Life forms - qualitative characters, Life Forms - Qualitative Characters ...

Life Forms - Qualitative Characters The form and structure of terrestrial communities are determined by the nature of vegetation. Vegetation may be classified according to gro

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