Large cells or contents are engulfed and digested by macrophages, thus forming a phagosome in cytoplasm. These phagosome fuse with lysosome for further digestion. • Exocytosis: Lysosomes release their enzymes outside the cell to digest other cells (Figure . ).
the inner and outer membrane. The inner membrane is smooth without ribosomes and the outer membrane is rough by the presence of ribosomes and it continues with irregular and infrequent intervals with the endoplasmic reticulum. The membrane is perforated by pores known as nuclear pores which allows materials such as mRNA, ribosomal units, proteins and other macromolecules to pass in and out of the nucleus. The pores enclosed by circular structures called annuli .
The pore and annuli form the pore complex . The space between two membranes is called perinuclear space . Chromatin is a viscous gelatinous substance that contains DNA, histone & non–histone proteins and RNA. H1, H2A, H2B, H3 and H4 are the different histones found in chromatin.
It is formed by a series of repeated units called nucleosomes. Each nucleosome has a core of eight histone subunits. Nuclear space is filled with nucleoplasm , a gelatinous matrix has uncondensed chromatin network and a conspicuous nucleolius . The Chromatin network is an uncoiled, indistinct and remain thread like during the interphase.
It has little amount of RNA and DNA bound to histone proteins in eukaryotic cells (Figure . ). Figure . : Structure of a Nucleus cells.
The membrane is absent in centriole (non-membranous organelle) (Figure . ). Figure . : Structure of Centriole .
. Vacuoles In plant cells vacuoles are large, bounded by a single unit membrane called Tonoplast . The Vacuoles contain cell sap, which is a solution of sugars, amino acids, mineral salts, waste chemical and anthocyanin pigments. Beetroot cells contain anthocyanin pigments in their vacuoles.
Vacuoles accumulate products like tannins. The osmotic expansion of a cell kept in water is chiefly regulated by vacuole and the water enters the vacuole by osmosis. The major function of plant vacuole is to maintain water pressure known as turgor pressure , which maintains the plant