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

Determine the chemical synaptic transmission, During chemical synaptic tran...

During chemical synaptic transmission A. neurotransmitter travels via diffusion in extracellular space. B. there will always be release of neurotransmitter from the postsyna

Define transcellular fluid compartment - extracellular fluid, Define transc...

Define transcellular fluid compartment - extracellular fluid? The transcellular fluid is a small compartment that represents all those body fluids which are formed from the tra

Phylum annelida are vascular beings, Q. What is signifying when it is said ...

Q. What is signifying when it is said that beings of the phylum Annelida are vascular beings? From which other phyla of the animal kingdom does this feature differentiate them?

What are sori, What are sori? The word "sori" is the plural form of "so...

What are sori? The word "sori" is the plural form of "sorus". In ferns, a sorus (pl. sori) is a cluster of sporangia on the edge or underside of a fertile frond. In lots of spe

Storage excretion, Storage Excretion Many insects exhibit a phenomenon...

Storage Excretion Many insects exhibit a phenomenon known as storage excretion. If excretory products are stored in the body instead of being eliminated, no water is expended

Quantitative characters - population density, Quantitative Characters - Pop...

Quantitative Characters - Population Density Density denotes the average number of individuals of a particular species in a unit area. In other words, it represents the numeri

Types of neurons, TYPE S OF NEURONS - The neurons are classified on th...

TYPE S OF NEURONS - The neurons are classified on the basis of their structure and function. (A) On the basis of the structure, the neurons are of four types.

Define the word glycemic, Glycemic or sugar control The control of bloo...

Glycemic or sugar control The control of blood sugar is one of the most important factors of good care for the diabetic patient. It has been shown that good glycemic or sugar c

Congenital anomalies of small and large intestines, Congenital Anomalies of...

Congenital Anomalies of Small and Large Intestines: 1) Intussusecption  Intussusecption  is the invagination or telescoping  of one part of  the intestine into another part

What is plastids, What is Plastids? The most obvious difference between...

What is Plastids? The most obvious difference between plant cells and other eukaryotic cells is that cells of most plants contain unique organelles called plastids, which inclu

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