Presentation on theme: "Viruses A submicroscopic pathogen From the Latin: Poison: A slimy liquid."— Presentation transcript:
Viruses A submicroscopic pathogen From the Latin: Poison: A slimy liquid
Viruses Not usually considered to be a living organism Symptoms depend on the host cells that they infect to reproduce Inserts its genetic material and takes over host’s functions to produce more viral protein and genetic material instead of the cell’s usual products.
Viruses Structure outside a host cell Has an inner core of nucleic acid (RNA or DNA) Protein coat surrounding nucleic acid Various sizes and shapes
Viruses Viruses attaches to a host cell Virus injects its DNA into host cell nucleus Then it can do one of two things 1)Lysogenic Phase RNA from virus becomes part of the DNA in host cell No obvious change in host cell It is in the dormant stage until virus gets triggered and enters the lytic cycle
Viruses 2) Lytic Cycle Host cell’s DNA is destroyed Cell’s machinery is used to produce new viruses The host cell breaks open to release the new viruses, which go and infect new cells
Effects of Viruses They cause disease in all living organisms When the virus breaks out of the host cell is usually destroys it Electron micrograph of a cluster of influenza viruses
Viruses This picture shows the structure of the Human Immunodeficiency Virus(HIV).
Effect of Viruses They cause disease in plants Micrograph of the virus that causes tobacco mosaic disease
Effect of Viruses They cause disease in bacteria We call them bacteriophages