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

Diagnosis of multiple myeloma, Which of the following abnormal blood work r...

Which of the following abnormal blood work results is most closely associated with a diagnosis of multiple myeloma? A. Extremely high levels of abnormal lymphocytes B. Low potassiu

Basic physical concepts of plant water relation, Basic Physical Concepts of...

Basic Physical Concepts of Plant Water Relation The main idea of this section is to explain the concept of chemical potential of water or water potential and the effect of var

Explain basal metabolism rate (bmr) - ageing, Explain Basal Metabolism Rate...

Explain Basal Metabolism Rate (BMR) - Ageing? From age 25 years, the basal metabolism decreases by about 2 percent for each decade due to the increasing proportion of body fat

Phosphorylation, Phosphorylation is the addition of the phosphate monoeste...

Phosphorylation is the addition of the phosphate monoester to a macromolecule, catalyzed by a particular kinase enzyme. With respect to the proteins, particular amino acid side ch

Counselling process of diabetic patient, Let us first learn about learn the...

Let us first learn about learn the points counsellor has to keep in mind for positive outcome of the counselling. The counsellor achieves the positive outcome of counselling, couns

Explain glycerol esters of fatty acids, Explain Glycerol esters of fatty ac...

Explain Glycerol esters of fatty acids Glycerol esters of fatty acids, which make up to 99% of the lipids of plant and animal origin have been traditionally called  fats and oi

Cobalt deficiency, Cobalt deficiency The deficiency of cobalt is more ...

Cobalt deficiency The deficiency of cobalt is more commonly seen in ruminants fed on diets deficient in this essential micronutrient. Cobalt is stored only in limited amounts

Prior to the solving of the structure of dna, Prior to the solving of the s...

Prior to the solving of the structure of DNA, Erwin Chargaff calculated the amounts of the four nucleotides (A, T,G,C) and made which of the following conclusions? A. All four

Describe prematurity in coronaw artery disease, Describe Prematurity in cor...

Describe Prematurity in coronaw artery disease ? CAD in Indians tends to be more aggressive and manifests at a younger age. Generally CAD occurring before the age of 55 years i

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