In this article we will discuss about the composition and importance of exince in pollen and spore walls. Composition of Exine: Exine is mainly composed of sporopollenin. Apart from sporopollenin glycoproteins are present in the chambers formed by bacula in tectate pollen. It is important in pollen-stigma interaction. The presence of glycocalyces (sing, glycocalyx) is reported from exine. Glycocalyx forms [...]
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 [...]
Sporoderm defines the shape of a pollen grain and spore. Erdtman (1952) distinguishes nine common types of shape (Fig. 4.33). The shape classes are based on the ratio between the length of polar axis (P) and equatorial diameter (E). P and E are measured from the equatorial view of a pollen grain and spore. Measurements are taken from the optical [...]