produced into the cell in the form of vesicles, tubules and lamellae. They are clumped and folded together to maximize their surface area and helps in respiration and in binary fission. Polysomes / Polyribosomes The ribosomes are the site of protein synthesis. The number of ribosome per cell varies from , to , .
The ribosomes are 70S type and consists of two subunits (50S and 30S). The ribosomes are held together by mRNA and form polyribosomes or polysomes. Flagella Certain motile bacteria have numerous thin hair like projections of variable length emerge from the cell wall called flagella. It is – μm in diameter and μm in length.
The flagella of Eukaryotic cells contain + microtubles but each flagellum in bacteria is made up of a single fibril. Flagella are used for locomotion. Based on the number and position of flagella there are different types of bacteria (Figure . ) Fimbriae or Pili Pili or fimbriae are hair like appendages found on surface of cell wall of gram-negative bacteria (Example: Enterobacterium ).
The pili are . to µm long with a diameter of about .025µm. In addition to normal pili there are special type of pili which help in conjugation called sex pili are also found. .
. Gram staining procedure The Gram staining method to differentiate bacteria was developed by Danish Physician Christian Gram in the year1884. It is a differential staining procedure and it classifies bacteria into two classes - Gram positive and Gram negative. The steps involved in Gram staining procedure is given in Figure .
. The Gram positive bacteria retain crystal violet and appear dark violet whereas Gram negative type loose the crystal violet and when counterstained by safranin appear red under a microscope. Most of the gram positive cell wall contain considerable amount of teichoic acid and teichuronic acid. In addition, they may contain polysaccharide molecules.
The gram negative cell wall contains three components that lie outside the peptidoglycan layer. . Lipoprotein . Outer membrane .Lipopolysaccharide.
Thus the different results in the gram stain Table . : Difference between Gram