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

Descent of the testis, Descent of the Testis The testis develops on ...

Descent of the Testis The testis develops on the posterior abdominal wall at the mesonephric ridge. To reach the adult position in the scrotum, it must decent. A fibrous cor

Is herbivorism a form of predatism, Q. Is herbivorism a form of predatism? ...

Q. Is herbivorism a form of predatism? The Herbivorism is a form of predatism in which first order consumers feed from producers (plants or algae). For instance, fruits and bir

What are the physical signs of mitral stenosis, Q. What are the Physical Si...

Q. What are the Physical Signs of mitral stenosis? A typical malar flush is described in mitral stenosis. It is difficult to appreciate in Indians. Pulse is normal or low volum

Explain evidence of coverage of ecology, Explain Evidence of coverage of Ec...

Explain Evidence of coverage of Ecology Evidence of coverage of Ecology and Evolution to the level of Descriptor 2 and an evaluation or  discussion that shows depth of underst

Show the process by which the neural impulse is transmitted, Q. What is the...

Q. What is the mechanism by which the neural impulse is transmitted along the axon? The neural impulse is transmitted along the neuronal membrane through depolarization of cons

Explain about implant surgery, Explain about implant surgery Diagnosis ...

Explain about implant surgery Diagnosis and treatment planning for a patient who requires and is to receive dental implants. The actual process of dental implant placement begi

Water soluble vitamins - b complex vitamins and vitamin c, Define Water sol...

Define Water soluble Vitamins - B complex Vitamins and Vitamin C? Vitamins are essential nutrients found in foods. The requirements are small but they perform specific and vit

Oogenesis, Oogenesis  The process of formation of ova in the ovary is c...

Oogenesis  The process of formation of ova in the ovary is called as oogenesis. The germ cells are found in the form of germinal epthelium around the ovary.These cells are d

Physiological adaptaion, what are the physiological adaptation shown my pre...

what are the physiological adaptation shown my prey as defence

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