Viruses Flashcards
What is a virus?
A non-cellular pathogenic agent, containing either DNA or RNA, that can only reproduce inside a living host cell.
List 5 structural features of viruses.
- Non-cellular and non-living.
- No membrane bound organelles.
- Have nucleic acid.
- Reproduce using host cells.
- Protective protein coat called a capsid.
Outline the 3 steps on how viruses work.
- Viruses inject nucleic acids into the host cell.
- Cell creates more virus particles.
- The host cell undergoes lysis releasing viruses that infect more cells.
Why can viruses often be referred to as an obligate parasite?
As viruses cannot function outside the host cells. Viruses cannot be grown outside living cells.
What are the 3 phases of the life cycle of a virus?
- Viral entry.
- Viral replication.
- Viral shredding.
Describe phase 1 (viral entry) of the life cycle of a virus.
Attaches to the host cell membrane. A hole forms in the membrane. The virus particle or its genetic contents are released into the host cell.
Describe phase 2 (viral replication) of the life cycle of a virus.
Viruses take control of the host’s cell replication mechanisms. It begins to make copies of itself and new viruses are assembled.
Describe phase 3 (viral shredding) of the life cycle of a virus.
The cell ruptures causing virus pparticles to be released to find new host cells.
List 3 examples of viruses.
- Influenza.
- Ross River virus.
- Honey Bee viruses.
What is the invasion method of the influenza virus?
Through mucous membranes.
What is the transmission method of the influenza virus?
Indirect - Airbourne droplets.
List 4 symptoms of the influenza virus.
- Fever.
- Dry cough.
- Sore throat.
- Stuffy nose.
List 3 different hosts of the Ross River virus.
- Humans.
- Possums.
- Bandicoots.
What is the invasion method of the Ross River virus?
Indirect - Via a vector by the injection into the blood by a mosquito bite.
List 4 symptoms of the Ross River virus.
- Joint pain and swelling.
- Muscle aches.
- SKin rashes.
- Fever and chills.
How many Honey Bee viruses exist that can cause Honey Bee diseases?
24 viruses.
Is there a cure for Honey Bee viruses?
No.
What is an example of a Honey Bee virus?
- Sacbrood.
What is the Sacbrood virus?
Infects larvae. The viruses mode of transmission may be foodborne. The virus replicated inside larval cells, causing larvae to display unusual behaviour. This virus can kill an entire colony.
What are the 2 different forms of evolution viruses experience?
- Antigenic drift.
- Antigenic shift.
What is antigenic drift?
Small changes that occur continuously over time.
What is the antigenic shift?
When two or more viral strains combine to form a new strain.
