Ultrastructure of Cell wall
*Main component of cell wall is cellulose
*β-D glucose molecule bonded with β-1,4 glycosidic bond to form cellulose
*Is cellulose molecule is 8 A diameter
*Michelle form bye joining 100-170 cellulose molecule parallelly
*20 Michelle join parallel to form microfibril (250Å)
*In microwave grill cellulose molecule together form 25 nm finute fibre spindle.
*Some microfiber together to form macrofibril
*Macrofibrils act as a unit of cell wall
*each macrofibrils is 0.4 μm
*Each macrofibril contain 5,00,000 cellulose molecule
*Under electron microscope it is shown that in cell membrane terminal complex and cellulose synthesis enzyme helps to synthesis cellulose
*empty part of macrofiber called matrix
*pectin fill the matrix part by joining a cross link with hemicellulose.
Thickening of cell wall
*In secondary cell wall substance like cellulose, lignin, pectin or suberin etc stored to thick cell wall
*The substances store unevenly to give the cell wall different structure like-----
a)Annular-
*The deposition of lignin takes place in the form of rings on the inner surface of the cell wall.
*The lignified rings are placed one above the other like coins leaving sufficient space between each other.
*The gap of the walls remain unthickened .
*Such thickness are commonly found in the vessels and tracheids.
b)spiral
In such cases the deposition of thickening material (lignin) takes place in the form of complete spiral bands. The number of such bands may be one or more than one. This type of thickening is commonly found in the vessels or tracheae of angiosperms.
c)Scalariform
In such thickenings of the cell wall the lignin is being deposited in the form of the transverse rods of the ladder, and thus known as scalariform or ladder-like. The unthickened areas between the successive thickening layers appear as elongated transverse pits. This type of thickenings are common in xylem vessels and tracheids of protoxylem.
d)reticulate
In such thickenings of the cell wall the thickening matter or lignin is being deposited in the form of a net or reticulum and thus known as reticulate or net like thickening of the cell wall. In such cases the unthickened areas of the cell wall are irregular in shape. These thickenings are commonly found in the vessels of the stems, roots and leaves of angiosperms and in the tracheids of protoxylem.
e)Pitted
In such thickenings of the cell wall, the whole inner wall is more or less uniformly thickened, leaving here and there some small unthickened areas, the pits.
Each pit has a pit Chember and pit membrane.
Pit are of 2 types-simple pit, border pit
*Main component of cell wall is cellulose
*β-D glucose molecule bonded with β-1,4 glycosidic bond to form cellulose
*Is cellulose molecule is 8 A diameter
*Michelle form bye joining 100-170 cellulose molecule parallelly
*20 Michelle join parallel to form microfibril (250Å)
*In microwave grill cellulose molecule together form 25 nm finute fibre spindle.
*Some microfiber together to form macrofibril
*Macrofibrils act as a unit of cell wall
*each macrofibrils is 0.4 μm
*Each macrofibril contain 5,00,000 cellulose molecule
*Under electron microscope it is shown that in cell membrane terminal complex and cellulose synthesis enzyme helps to synthesis cellulose
*empty part of macrofiber called matrix
*pectin fill the matrix part by joining a cross link with hemicellulose.
Thickening of cell wall
*In secondary cell wall substance like cellulose, lignin, pectin or suberin etc stored to thick cell wall
*The substances store unevenly to give the cell wall different structure like-----
a)Annular-
*The deposition of lignin takes place in the form of rings on the inner surface of the cell wall.
*The lignified rings are placed one above the other like coins leaving sufficient space between each other.
*The gap of the walls remain unthickened .
*Such thickness are commonly found in the vessels and tracheids.
b)spiral
In such cases the deposition of thickening material (lignin) takes place in the form of complete spiral bands. The number of such bands may be one or more than one. This type of thickening is commonly found in the vessels or tracheae of angiosperms.
c)Scalariform
In such thickenings of the cell wall the lignin is being deposited in the form of the transverse rods of the ladder, and thus known as scalariform or ladder-like. The unthickened areas between the successive thickening layers appear as elongated transverse pits. This type of thickenings are common in xylem vessels and tracheids of protoxylem.
d)reticulate
In such thickenings of the cell wall the thickening matter or lignin is being deposited in the form of a net or reticulum and thus known as reticulate or net like thickening of the cell wall. In such cases the unthickened areas of the cell wall are irregular in shape. These thickenings are commonly found in the vessels of the stems, roots and leaves of angiosperms and in the tracheids of protoxylem.
e)Pitted
In such thickenings of the cell wall, the whole inner wall is more or less uniformly thickened, leaving here and there some small unthickened areas, the pits.
Each pit has a pit Chember and pit membrane.
Pit are of 2 types-simple pit, border pit
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