Membrane structure and function
ABOUT CELL-
A cell is a structural and functional unit of all organisms. The cell was discovered by Robert hooke in 1665. In actually Hooke discover a non living cell. first living cell is discovered by Antony von Leeuwenhoek who described the algae Spirogyra. MJ Schieiden and T Schwann give the cell theory in 1839.
Cell theory-
1.All life forms are made from one to more cells.
2.New cell formed by pre existing cells.
3.A cell is a smallest form of life.
definition of cell membrane- the cell membrane is the outer layer of cell body which septate cell from outer environment. the membrane control molecules and ions who come and go out from cell.
Thickness- plasma membrane is very thin its thickness is nearly 75Å but it may be different in different types of cell. in RBC its thickness is 21.5Å.
ULTRASTRUCTURE-
the structure of plasma membrane is tree layered-
(a)20Å thine outer layer
(b)20Å thine inner layer
(c)middle layer between outer or inner layer of 35Å
the outer and inner layer is made of protein and middle layer is phosphpholipid layer. first modal of plasma membrane is presented by Daniel and Davison in 1935.
CHEMICAL COMPOSITION-plasma membrane is mostly made of protein and lipid and some quantity of carbohydrate is also founds.
read about DNA Molal-
DNA MODAL
Different models of plasma membrane-
1. Lamellar theory-this theory is given by Annelida and Davison in 1935. according to this theory in plasma membrane structure there is one bimolecular layer of phospholipid is presents between two layers of protein. non-poler hydrophobic ends of both layer are arranged by facing. but poler hydrophilic ends are connected with protein molecules .one protein molecule connects with 75 to 90 molecules of lipid.each layer of phospholipid is separates by CHOLINE BASE. one cholesterol molecule is found between two molecules of phospholipid.
3.Fluid mosaic model- this theory is given by Singer and Nicholson. in this theory these are important points-
(a) lipid molecules made double layer which made skeleton of plasma membrane. intrinsic protein is presents inside of this and view like mosaic.
(b) intrinsic protein and lipid both are amphipathic. poler end is present on surface side.
(c)amphipathic protein made liquid crystal pair. lipid molecules also built a layer and arranged between protein layer in this way that poler ends shows on outer surface. and by this structure active place for enzymes are presents outside cell membrane.
you can also read about-
BLOOD AND CIRCULATION
Continue........
ABOUT CELL-
A cell is a structural and functional unit of all organisms. The cell was discovered by Robert hooke in 1665. In actually Hooke discover a non living cell. first living cell is discovered by Antony von Leeuwenhoek who described the algae Spirogyra. MJ Schieiden and T Schwann give the cell theory in 1839.
Cell theory-
1.All life forms are made from one to more cells.
2.New cell formed by pre existing cells.
3.A cell is a smallest form of life.
definition of cell membrane- the cell membrane is the outer layer of cell body which septate cell from outer environment. the membrane control molecules and ions who come and go out from cell.
Thickness- plasma membrane is very thin its thickness is nearly 75Å but it may be different in different types of cell. in RBC its thickness is 21.5Å.
ULTRASTRUCTURE-
the structure of plasma membrane is tree layered-
(a)20Å thine outer layer
(b)20Å thine inner layer
(c)middle layer between outer or inner layer of 35Å
the outer and inner layer is made of protein and middle layer is phosphpholipid layer. first modal of plasma membrane is presented by Daniel and Davison in 1935.
read about DNA Molal-
DNA MODAL
Different models of plasma membrane-
1. Lamellar theory-this theory is given by Annelida and Davison in 1935. according to this theory in plasma membrane structure there is one bimolecular layer of phospholipid is presents between two layers of protein. non-poler hydrophobic ends of both layer are arranged by facing. but poler hydrophilic ends are connected with protein molecules .one protein molecule connects with 75 to 90 molecules of lipid.each layer of phospholipid is separates by CHOLINE BASE. one cholesterol molecule is found between two molecules of phospholipid.
LEARN ABOUT PROTEIN ON THIS LINK-
2. Micellar theory- according to Hillier and Hoffman plasma membrane is made of pounded subunits or micellar. every subunit has central cord. protein particles are presents in molecular layer. 4Å gape between pounded micellar indicates water holes. micellar structure founds in intra cytoplasmic membranes not in cell membrane.
(a) lipid molecules made double layer which made skeleton of plasma membrane. intrinsic protein is presents inside of this and view like mosaic.
(b) intrinsic protein and lipid both are amphipathic. poler end is present on surface side.
you can also read about-
BLOOD AND CIRCULATION
Continue........
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