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 [...]
Plasmodesma (plural: plasmodesmata) is thin irregular cylinder of cytoplasm lined by plasmalemma, passing through fine pores in the cell walls, thus forming a connection between the cytoplasm of adjacent cells. They are found in higher plants and fluctuate widely in abundance and distribution. They are commonly present in primary pit fields and pit membranes of young and mature living cells [...]