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4C Viruses. NONLIVING Contain either DNA or RNA (but NEVER Both). VIRUS. Why is a virus considered non-living?. They cannot replicate on their own (without a host cell) They cannot obtain and use energy They cannot respond to the environment. What a virus does. It invades a cell .
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NONLIVING • Contain either DNA or RNA (but NEVER Both) VIRUS
Why is a virus considered non-living? • They cannot replicate on their own (without a host cell) • They cannot obtain and use energy • They cannot respond to the environment
What a virus does It invadesa cell. It turns the cell into a virus making factory until it no longer needs the cell. It then destroys the cell releasing new viruses to continue the cycle.
How does a virus replicate? Virus injects it’s genetic info into a host cell. Host cell then “replicates” viral DNA to makes new viruses
How do they replicate?(replicate means to make more)LYTIC CYCLE
Lysogenic Cycle Wait for animation
LYSOGENIC CYCLE • takes longer to destroy host cell LYTIC CYCLE • destroys host cell in a short amount of time
Types of Viruses • Adenovirus • Retrovirus • Bacteriophage
Adenovirus • any of a group of DNA viruses first discovered in adenoid tissue, most of which cause respiratory diseases
Retroviruses • Made of RNA • Inject their RNA into the host cell • Host cell makes it into DNA • Viral DNA joins the host DNA • Viral DNA pirates the cell and forces the cell to make new viral RNA and new viruses HIV is a retrovirus
Bacteriophage Virus that attacks bacteria
Common Viral Diseases • Rhinoviruses cause the common cold • HPV (Human papillomavirus) can cause cervical cancer in women • Herpes simplex viruses cause mouth and/or genital sores, lesions, and ulcers. • Influenza viruses cause the flu • HIV (Human Immunodeficiency Virus) causes AIDS and weakens the immune system
How is a disease caused by a virus? • New viruses made inside BURST out of and destroy host cell • When your cells die your health is affected
Controlling Viruses • Antibiotics DO NOT work on viruses. • Most human viral infections can be fought off by the immune system—boost the immune system with lots of water and rest.
How does a VACCINE work? • Vaccines stimulate the immune system to create antibodies that recognize a certain virus… • Vaccines inject a small amount of the virus into your system.
How do vaccines work? • The body then builds antibodies to fight that specific virus. • Antibodies remember that virus in the future in case you are exposed to that virus again. • These antibodies patrol your body and if they recognize that virus…they call in reinforcements and your immune system goes to battle!
Compare viruses to living cells What do they have in common? They have DNA & RNA and They both change over time