Download Virus PPT

Viruses
• Non-living - does not grow, eat, release
waste, or breathe.
• Is able to reproduce, but only when
inside a host (the cell that a virus
enters)
• 100 times smaller than bacteria
Virus • A nucleic acid core encased in a protein coat
that can infect cells and replicate within
them
Structure of a Virus
• Capsid (protein coat)
• Nucleic Acid (DNA)
• Tail
• Tail Fibers
REPRODUCTION
1. Viruses cannot reproduce on their
own
2. They need a host cell to do all the work
3. It is a five step process called the
Lytic Cycle that ends in the host cells
death.
Viral Reproduction - Lytic Cycle
1. Attachment - Virus attaches to the Host
cell
2. Penetration - Virus injects its RNA or
DNA
3. Replication - Host cell makes many
copies of the viral RNA or
DNA
4. Assembly - Host cell builds new viruses
5. Lysis - New viruses breaks out of host
cell -killing it – to attack other hosts
4
2
1
5
3
1. Attachment
2.
3.
4.
5.
Penetration
Replication of DNA
Protein assembly - making new viral coats
Lysis
Attachment/Penetration
LYSIS
MOBILITY
• Viruses do NOT move on their own
• Transferred by water, air, food, human
contact
MOVEMENT
VIRAL DISEASES
Pathogenic (disease causing)
• Flu
• Hepatitis C
• Mumps
• Measles
• Ebola
• Polio
Polio
• HIV
How are viruses treated?
• Antibiotics/medicines do NOT work
on viruses
• About the only treatment is to drink
plenty of fluids and bed rest. Some
medicines may improve symptoms
such as aspirin for fever.
What are vaccines?
• Vaccinations (can be live, dead or
weakened)
• Vaccinations prevent you from getting that
particular virus
• The flu virus mutates so rapidly that
vaccines are a challenge
• HIV virus attacks the immune system mutates VERY rapidly - vaccine difficult