Introduction

STRUCTURE AND FUNCTION: BACTERIAL CELLS

INTRODUCTION

Bacterium (pl. bacteria) refers to a single-celled organism without having a true nucleus or functionally specific components of metabolism that belongs to the kingdom Prokaryotae (Monera). The internal cytoplasm is invariably surrounded by one-or two-layered rigid cell wall composed of phospholipids. Some bacteria also produce a specific mucoid extracellular capsule for additional pro-tection, particularly from phagocytosis by white-blood cells (WBCs). Bacteria can synthesize nucleic acids (DNA, RNA), other important proteins and can reproduce independently, but may essentially need a host to supply food and also a supportive environment. In reality, millions of nonpathogenic bacteria live on the skin and mucous membranes of the human gastrointestinal tract (GIT) ; these are termed as normal flora. Importantly, bacteria that cause disease are usually known as pathogens.