INTRODUCTION

• Kingdom Monera comprises the simplest organisms of Earth and are unicellular and microscopic.
• Monera consists of

1. Bacteria
2. Mycoplasma
3. Actinomycetes
4. Cyanobacteria
5. Rickettsia

SALIENT FEATURES OF MONERA

• Prokaryotes are simple organisms that lack a true nucleus and majority of the membrane-bound organelles like endoplasmic reticulum, Golgi apparatus, lysosomes etc.
• DNA of prokaryotes is termed as nucleoid and their DNA is arranged in the form of a single chromosome.
• They reproduce mainly by asexual means mainly binary fission.

BACTERIA

• Bacteria were the first organisms to survive on planet earth after life originated around 3.5 billion years ago.
• They are unicellular organisms, structurally simple and microscopic and range in size from 0.1 to 10 microns.
• Bacteria are prokaryotic and do not possess any membrane-bounded nucleus or other intracellular organelles.
• Their genetic material is structured into a single circular chromosome containing deoxyribonucleic acid (DNA) and reproduces through conjugation and binary fission.

ACTINOMYCETES

• The Actinomycetes are a group of Gram-positive bacteria which form branched filamentous hyphae and are usually rod shaped having a filamentous and branched structure.
• Actinomycetes are most abundant in soil and marine habitat.

MYCOPLASMAS

• Mycoplasmas are ubiquitous intracellular gram negative type bacteria.
• Majority of mycoplasma organisms are motile, and they use their gliding motility for movement instead of pili or flagella.
• Instead of a cell wall, they contain a three-layered membrane, containing sterol, which is taken up from the environment.

CYANOBACTERIA

• Cyanobacteria are more commonly known as Blue-Green Algae
• Blue-green algae are the most primitive organisms. They are not considered “true-algae”. They resemble bacteria in structure and therefore were placed in kingdom Monera.
• They are single-celled organisms and thus contain a simple structure.
• Cyanobacteria reproduce asexually, either through binary fission or multiple fission.

Rickettsia

• Rickettsia species are small, Gram-negative bacilli
• They consist of the Genera Rickettsiae, Ehrlichia, Orientia, and 
• They cause diseases in humans such as typhus, Boutonneuse fever, African tick bite fever, Rocky Mountain spotted fever etc.
• Rickettsia can be classified into three main groups, on the basis of serology and DNA sequencing:

1. Spotted fever
2. Typhus
3. Scrub typhus.