Topic 3: Viruses Flashcards
Are viruses cellular or non-cellular?
Non cellular
Examples of Cellular Pathogens
Consists of living cells - bacteria, fungi, protozoans
Examples of Non-cellular
Non-living: viruses, prions
5 different types of pathogens
Bacteria, Viruses, Protozoa, Fungi, Prions
How do pathogens cause infection disease?
They stop cells functioning normally, causing disease.
Are viruses living? Explain
No - they lack cellular components, and are missing either DNA or RNA making them unable to replicate outside of a host cell. THEY CANNOT REPRODUCE WITHOUT A HOST CELL
Examples of Viral diseases
- Influenza (Common Cold)
- Hepatitis
- HIV
What are the two main structures that all viruses have?
- Genetic Material - DNA or RNA
- Capsid (Protein Shell of a virus)
How does a virus recognise its host cell to invade?
The virus’ surface protein can only bind to specific cell receptors, which determines which cells a virus can infect.
The virus attaches to these host cells’ receptors on the host cell surface.
Stages of VIRAL infection (Stage 1)
Attachment:
- the virus enters the host organism and finds a host cell to invade
- attaches to the host cell receptors with its surface proteins
Stages of VIRAL infection (Stage 2)
Entry:
- the virus injects its nucleic acid into the host cell
- may even engulf the viral particle taking it into the cell
Stages of VIRAL infection (Stage 3)
Assembly:
- the viral nucleic acid hijacks the host cell and directs the cell to make viral nucleic acid and protein coats
Stages of VIRAL infection (Stage 4)
Release:
- new viruses are assembled and are released when the host cell lyses (bursts open)
- now there are thousands or viral pathogens which can infect other cells.
How are viruses spread?
- Contact Eg; Respiratory droplets (coughing, sneezing)
- Vehicle Eg; HIV (bodily fluids)
- Vector Eg; Hendra Virus
What treatment is used for viral infections?
- Antiviral drugs (if severe)
- Stay home
- Rest (allow immune system time to fight back)
- Vaccines (as a preventative measure)
