Growth of cell wall involves the growth in surface area as well as growth in thickness. Normally, the entire cell wall grows. Localized growth occurs in fibres, root hairs, tracheids and pollen tubes. A new primary wall grows in surface area. The wall expands due to the turgor pressure exerted on the walls by the protoplast. Turgor pressure is developed [...]
In this article we will discuss about the chemical composition and functions of plasma membrane. Chemical Composition of Plasma Membrane: The membrane is mainly composed of lipids, proteins and carbohydrates. Water makes about 29% of total weight. Robertson (1959) proposed that plasma membrane is three-layered structure where proteins form the outer and inner layers of membrane that encloses lipids to [...]
In this article we will discuss about the layers of the spore and pollen wall. Sporoderm stratification (Erdtman's concept): Sporoderm (L. sporodermis), i.e. the spore and pollen wall is composed of distinct layers or subdivisions, the sequence of which is as follows from outside inwards in a fresh pollen grain and spore. Sclerine (Gr. Scleros means hard-Fig. 4.1 A & [...]