Microorganisms: Characteristics of Virus and Bacteria

Characteristics Of Living Organisms 

Following are the main characteristics of living beings that are not present in non-living organisms.

1. Metabolism
2. Growth
3. Irritability
4. Reproduction
5. Movement
6. Nutrition
7. Respiration
8. Excretion

Also Read: Stages and Characteristics of Mitosis and Meiosis

Virus

• Viruses are micro-organisms that are strict or obligate parasites of animals or plant cells. Many of the viruses are also parasites on bacteria.
• A large number of viruses cause diseases in plants and animals.

Characteristics Of Virus

• A virus consists of two components, a protein coat and a core of nucleic acid which is either DNA or RNA.
• DNA viruses are called adenoviruses and RNA viruses are called retroviruses.
• The shape of a virus is due to its protein coat.
• Viruses are of many shapes i.e. rods, spherical, hexagonal, or icosahedral.
• Sometimes their shape is complicated.
• Viruses replicate inside a living cell and many viruses are synthesized along with their protein coats and nucleic acid.
• The nucleic acid contains instructions for the shape of the virus.

Diseases Caused By viruses

• Polio
• AIDS
• Smallpox
• Measles
• Hepatitis

Bacteria

Characteristics Of Bacteria

• Bacteria are unicellular prokaryotic organisms that generally divide by transverse binary fission.
• They possess rigid cell walls and act as pathogens
• The nucleus is not well organized
• No definite chloroplast, chlorophyll is dissolved in chromoplasm.

There are three forms of bacteria which are:

1. Round called Cocci
2.  Rod-like called Bacilli
3. Spiral called Spirrila

Classification Of Bacteria According To Mode Of Nutrition

According to the mode of nutrition, there are three types of Bactria:

a) Parasitic:

• Devoid of chlorophyll
• Are heterotrophic and get food from living animals and plants

b) Saprophytic

• Lack chlorophyll hence cannot prepare their own food.
• Get food from dead organic remains

c) Autotrophic

• Contain chlorophyll
• Can synthesis food by photosynthesis
• Few get their food by chemosynthesis

Reproduction In Bacteria

1. Vegetative: By Binary Fission
2. Asexual: By Formation of Endospores
3. Sexual: By Conjugation

Also Read: General Science and Ability Notes and Mcqs