GENERAL CHARACTERISTICS OFVIRUS & BACTERIA

Anand Charvin & Bhakar Ningombam

BACTERIAL CHARACTERISTICS

Bacterial Characteristic

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Bacteria are of immense importance because of

their rapid growth, reproduction, and

mutation rates, as well as, their ability to exist

under adverse conditions.

The oldest fossils known, nearly 3.5 billion years

old, are fossils of bacteria-like organisms.

Bacteria

Autotrophs Heterotrophs

• Those that are classified as autotrophs are either photosynthetic, obtaining energy from sunlight or chemosynthetic, breaking down inorganic substances for energy .

• Bacteria classified as heterotrophs derive energy from breaking down complex organic compounds in the environment.

• This includes saprobes, bacteria that feed on decaying material and organic wastes.

BACTERIA STRUCTURE AND TYPES

BACTERIA

• Bacteria are often maligned as the causes of human and animal disease. However, certain bacteria, the actinomycetes, produce antibiotics such as streptomycin and nocardicin.

• Bacteria live on the roots of certain plants, converting nitrogen into a usable form.

• Bacteria make up the base of the food web in many environments.

About:Bacteria

Bacteria are prokaryotic

and unicellular.

Bacteria have cell walls.

Bacteria have circular DNA

called plasmids

Bacteria can be anaerobes or aerobes.

Bacteria can be

heterotroph or autotroph

Bacteria can be useful as

well as pernicious.

GENERAL CHARACTERISTICS OF VIRUS

Viruses are infectious agents with both living and nonliving characteristics.

1. Living characteristics of viruses

a. They reproduce at a fantastic rate, but only in living host cells.

b. They can mutate.

2. Nonliving characteristics of viruses

• They are a cellular, that is, they contain no cytoplasm or cellular organelles.

• They carry out no metabolism on their own and must replicate using the host cell's metabolic

machinery.

GENERAL STRUCTURE OF VIRUS

Viral components• Nucleic acids• Capsid• Envelope

CHARACTERISTICS OF VIRUS

Virion (Virus particles) size range

is ~10-400 nm

All virions contain a nucleocapsid which

is composed of nucleic acid (DNA or RNA) and a protein

coat (capsid)

Some viruses consist only of a

nucleocapsid, others have additional

components

Envelopes• virions having envelopes

= Enveloped viruses• virions lacking envelopes

= Naked viruses

THE ENVELOPE

Many viruses that infect humans and other animals are enveloped.

Envelopes form when viral glycoproteins and

oligosaccharides associate with the plasma membrane of the

host cell.

All envelopes have a phospholipid bilayer.

VIRUS CLASSIFICATION