B.sc.1 viruses general characteristics

B.SC.-1,UNIT-1 BOTANY

1. VIRUSES Presented By Kanchan Sinha ShriShankaracharyaMahavidyalaya,Junwani,Bhilai

2. INTRODUCTION Virus: a microscopic particle that gets inside a cell and often destroys the cell • Viruses are tiny • Smaller than the smallest bacteria • Change rapidly • So small and change so often that scientists don’t know exactly how many types exist • These properties make viruses difficult to fight

3. Definition

4. HISTORY

5. CHARACTERISTICS OF VIRUS Viruses are obligate intracellular parasites of bacteria, protozoa, fungi, algae, plants, and animals. Ultramicroscopic size, ranging from 20 nm up to 450 nm (diameter). Viruses are smaller than bacteria . Not cellular in nature; structure is very compact and economical. Do not independently fulfill the characteristics of life . Inactive macromolecules outside the host cell and active only inside host cells. Basic structure consists of protein shell ( capsid ) surrounding nucleic acid core. Nucleic acid can be either DNA or RNA but not both.

6. CHARACTERISTICS OF VIRUS  Nucleic acid can be double-stranded DNA, single- stranded DNA single-stranded RNA, or double-stranded RNA. Molecules on virus surface impart high specificity for attachment to host cell. Multiply by taking control of host cell’s genetic material and regulating the synthesis and assembly of new viruses. Viruses lack cellular organelles, such as mitochondria and ribosomes . Lack ribosome and enzymes needed for metabolism  . Use the raw materials and enzymes of the host cell to be able to reproduce  . Lack machinery for synthesizing proteins. Most RNA viruses multiply in & are released from the cytoplasm. Viral infections range from very mild to life threatening . Viruses are parasites-A parasite is an organism that depends upon another living organism for its existence in such a way that it harms that organism

7. SHAPES OF VIRUS There are four main shape of virus -

8. TAXONOMY OF VIRUSES Family names end in - viridae Genus names end in - virus Viral species : A group of viruses sharing the same genetic information and ecological niche (host). Common names are used for species. Subspecies are designated by a number .

9. REFERENCES https:// www.slideshare.net/RIZWANABBAS3/viruses-structure-classification-and-characteristics https:// www.slideshare.net/vidhyakalaivani29/virusessizeshape-types https:// www.slideshare.net/kmtschida/virus-powerpoint https:// www.slideshare.net/jdrinks/viruses-ppt-15932866 https ://www.slideshare.net/rajendra930136/virus-23717258?next_slideshow=1