The size of a typical eukaryotic cell is 10 – 20 μm. Prokaryotic cells are generally smaller than eukaryotic cells and also multiply more rapidly. Bacteria, blue-green algae, mycoplasma and PPLO (Pleuro Pneumonia Like Organisms) are types of prokaryotic cells.

The inner compartment of rough endoplasmic reticulum is called luminal compartment. The ribosomes are attached to outer surface and it is actively involved in protein synsis.

Bacterial have a tightly bound three – layered cell envelope. The uppermost layer is glycocalyx, followed by cell wall in middle and innermost plasma membrane. The cell envelope provides protection.

Omnis cellula-e cellula, means that each cell is derived from a pre-existing cell by cell division. It is culmination of a profound insight of late 19th century and stated by German pathologist Rudolf Virchow.

The functions of endoplasmic reticulum (ER), Golgi bodies, vacuoles and lysosomes are coordinated. Hence, y form an endomembrane system. Peroxisomes are not a part of endomembrane system.

The cell membrane is a phospholipid bilayer. The cell membrane has two types of proteins- peripheral proteins and integral proteins. Peripheral proteins are present on surface of membrane.

The nuclear matrix or nucleoplasm contains nucleolus and chromatin. The nucleolus is site for active ribosomal RNA or rRNA synsis. The nucleolus is not bound by a membrane.

Some chromosomes have secondary constrictions which are non – staining, apart from centromere. They give appearance of a small fragment. This small fragment is known as a satellite.

The algal cell wall contains cellulose, galactans, mannans and minerals like calcium carbonate. The plant cell wall contains cellulose, hemicellulose, pectins and proteins. Hence, cellulose is common component.

The ?S? in 80S ribosome, or Svedberg?s Unit, stands for sedimentation coefficient. The sedimentation coefficient (S) of a particle characterizes rate of sedimentation during centrifugation.