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

Mycroboilogy mycoplasma, How we write assimgment about mycobiology of mycop...

How we write assimgment about mycobiology of mycoplasma in detail

Define hexose monophosphate pathway, Define hexose monophosphate pathway ...

Define hexose monophosphate pathway The hexose monophosphate pathway (HMP also called the pentose phosphate pathway, or phoshogluconate pathway) consists of Mo irreversible o

Animal husbandry-source of energy and protein, Source of Energy and Protein...

Source of Energy and Protein The by-products obtained from grain processing (brans), oil seed processing (oil meals) and pulses processing industries are the major and importan

What is predatism, What is predatism? Predatism is the ecological inte...

What is predatism? Predatism is the ecological interaction in which one individual mutilates or kills another to get food. Predatism is an inharmonious (negative) ecological i

Behavioural adjustments, Behavioural Adjustments When faced with a su...

Behavioural Adjustments When faced with a sudden temperature change, most animals make behavioural responses that enable them to avoid extreme or lethal conditions. Among the

Digestive system of an arthropod, how does the digestive system of an arthr...

how does the digestive system of an arthropod operate

Explain metameric in detail., Explain Metameric in detail. A body plan ...

Explain Metameric in detail. A body plan which consists of a series of identical units, metameres, repeated down longitudinal axis of the animal. Every metamere contains identi

Explain the nutritional and functional role of potassium, Minerals :- Potas...

Minerals :- Potassium Food Source      Fruits, vegetables, meats Nutritional Functional role Essential nutrient: Deficiency is rare. Salt substitute: KCl may be

Explain that a peptide bond a covalent, Is a peptide bond a covalent or a n...

Is a peptide bond a covalent or a non-covalent bond? Please explain.

Measurement of species diversity, The measurement of species diversity prov...

The measurement of species diversity provides an important preliminary assessment of overall biodiversity. There are many ways by which species diversity is measured i.e. species r

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