The major route for endocytosis in most cells, and the best-understood, is that mediated by the molecule clathrin. This large protein assists in the formation of a coated pit on the inner surface of the plasma membrane of the cell.This pit then buds into the cell to form a coated vesicle in the cytoplasm of the cell.he major route for endocytosis in most cells, and the best-understood, is that mediated by the molecule clathrin. This large protein assists in the formation of a coated pit on the inner surface of the plasma membrane of the cell.
Sponges are extremely primitive invertebrate life so are classed under the Kingdom Animalia, they do not photosynthesise so are not plants. They are also very different to fungi and have an entirely different composition and life cycle. A sponge if passed through a sieve gradually reforms its original shape.ponges are extremely primitive invertebrate life so are classed under the Kingdom Animalia, they do not photosynthesise so are not plants. They are also very different to fungi and have an entirely different composition and life cycle. A sponge if passed through a sieve gradually reforms its original shape.
Spicules of Sponges. 1  Spicules are formed by scleroblast cells present in the mesenchyme. 2  They consists of an axis of organic material around which calcium carbonate or silica is deposited. 3  They are of various shapes. 4  Monaxons-single axis growing in one or more directions. 5  Triaxons-three axes crossing each other and have six rays. 6  Tetraxons-four ...eneral Characteristics of Porifera. 1  Poriferans are commonly called sponges. 2  These are multicellular organisms which are sessile/sedentary in nature. 3  Most of them are marine while a few are fresh water forms. 4  Body is cylindrical, asymmetrical or has radial symmetry.