Chapter 6 - Viruses

Viruses

infectious particle and can hijack and take over the cell.

• Non living when outside the cell but when they make it to the cell, they become living (on going debate)

• Has genetic material DNA OR RNA, do not have both at the same time 

  • Can have single stranded DNA and can have double stranded DNA

  • Can have single stranded RNA and can have double stranded RNA 

• Protein coating outside as well

• Very very small but can be a big issue for the health

• 2 major type of virus 

  • Naked capsid viruses

  • Steal cell membrane from human bodies to hide under the mask for shield from the immune system, Enveloped virus. 

Cannot take antibiotics, antibiotics are only for bacteria not for viruses.

Virus classification

- very specific, and gets classified based on what they infect, shape, genetic material, and kind of disease that you get from the disease. 

- Cannot use a light microscope because viruses are that small. 

- Bacteriophage - weird head, steal fibers, will specifically infect bacteria 

attachment

Viruses have an ATTACHMENT, always constantly trying to attach but not every one has an attachment.

• Tropism - lock and key

Once viruses find the right match, they PENETRATE

• Envelope virus

Transcription

• Inject its genes DNA or RNA into the cell 

• Try to hijack all the cell organelles to make their own proteins 

Translation

• Will make a viral army in the cells and make more.

Army of viruses in the cell. 

• Hijacked and hypnotized ending up harming your body. 

They always damage something in many ways, making cells really weak before they leave.

• Can cause many many outcomes

• It's never just outcomes, there are a lot of outcomes.

• Persistent infections, viruses are constantly eating up the cells, sickness keeps coming back. 

• Worst possible outcome of the cells, viruses can turn normal cells into cancerous cells 

• Viruses by stealing plasma membranes of your own cells. 

• Latent infections are chicken pox, waiting for the right moment to attack. 

Retro viruses

first RNA genetic material, enzyme called reverse transcriptase and will convert rna to dna, can mess up people’s DNA. Ended up being able to mess up your DNA because the viruses will be able to modify it.

Lytic cycle

genetic material is injected into the cell and can replicate

– Viral DNA is injected into host cell

• Contains instructions needed to make more viruses

– Host cell replicates viral DNA and makes the viral

capsids (protein coats)

– New viruses are assembled inside host cell

– Cell bursts open releasing new viruses

lysogenic cycle

genetic material is mixing with the host’s genetic material

– Viral DNA is injected into the host cell

– Viral DNA inserts itself into the host’s DNA

– Remains inactive for days, months, or years

– As the cell reproduces, more cells are produced that

have the viral DNA in them

– Eventually, when the conditions are favorable (like

when your immune system is weakened) the virus will

enter the lytic cycle

treatment of virus

• Antibiotics: Do not work on viruses…

they are not living

Virus treatment options:

Antivirals: specific for infection

Tamiflu®, Relenza®, etc.

Body’s natural defenses: Immune system

Rest

Antioxidants

“Feed a cold, starve a fever”?

Vaccines are taken beforehand to prevent infections by introducing the immune system to viral recognition signals.

Subject to controversy…