general organization and characterstics of virus
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ORGANIZATION AND CHARACTERSTICS OF VIRUSES
BARKATULLAH UNIVERSITY BHOPAL
PRESENTED BY MUHAMMAD ASIF KANTH
SUBMITTED TO :- DEPARTMENT OF ZOOLOGY AND APPLIED AQUACULTURE
M.SC IV SEM
VIRUS is either DNA or RNA, that is protected by a protein coat called a CAPSID.
Viruses:A • are noncellular or Acellular infectious agentsVirology:• study of viruses
Virologists:• scientists who study viruses
The concept of a virus as an organism challenges the way we define life:
* Viruses do not breathe.* Viruses do not metabolize.* Viruses do not grow.* However, they do reproduce.
General features of VirusesViruses 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.
…General features of Viruses2. Nonliving characteristics of viruses
They are acellular, 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 FEATURES OF VIRUSES
Virus particles contains either DNA or RNA (not both)
Nucleic Acid is surrounded or coated by a protein shell (capsid)
Some viruses possess a membrane-like envelope surrounding the particle
…General Properties of virusesConsists of 1 molecule of DNA or RNA
enclosed in coat of proteinMay have additional layersCannot reproduce independent of living
cells nor carry out cell division as procaryotes and eucaryotes do
An intact viral particle is called a virion.
V - Release- Assembly of virus
DNA and protein coat into whole new viruses
- Leaving the cell
ASIF KANTH M.SC IV SEM
Phase IV Phase V
I, II, III - Viruses enter cell- Attachment to cell
membrane- Penetration inside cell- Losing virus protein coat
IV - Replication- Tricks cell into
making more viral DNA
- Tricks cell into making viral protein coat
Viruses Can Help Cells, Too
- Since viruses can transport DNA and RNA into cells, scientists are exploring Gene Therapy
- In Gene Therapy, viral genetic material is replaced with new DNA
- In time, this could be used to cure genetic diseases. Currently we have no cure for these types of illnesses
DISEASE VIRUSESAIDS HIV
Wart Herpes Simplex Virus
Measles Morbillivirus .
Cancer Hepatitis B
Examples of some viral diseases:
The Size and Morphology of Selected Viruses
Generalized Structure of Viruses
Viral componentsNucleic acids
…Generalized Structure of Viruses
The Structure of Viruses
Virion size range is ~10-400 nmAll 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
VIRAL ENVELOPES• 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
The End! And ReviewViruses are very simple: a shell containing
either DNA or RNA.They infect by hijacking cells’ machinery to
force them to make more viruses.Viruses are tiny, even compared to a cell.Some viruses may prove useful in gene
therapy as natural carriers of DNA that was specially designed to be good for a particular reason.