1. Viruses: Identify basic structures of a virus
Describe stages of lysogenic and lytic cycle
*this is dengue fever
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2. Viruses
Have some characteristics of living organisms, such as the ability to replicate, but they are not considered living
They can only reproduce by using the metabolic machinery of a host cell
Viruses do not have a metabolism, and do not respond to stimuli
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3. 1884 – Louis Pasteur suggested that something smaller than bacteria was the cause of rabies
He chose the work virus from the Latin word meaning “Poison”
In the twentieth century, electron microscopy was born and viruses were seen for the first time
This is gonorrhea, an STD
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Discovery of Viruses

4. Structure of Viruses
Viruses are best studied under electron microscopes
Viruses are categorized by their
Size and shape
Type of nucleic acid – single or double stranded
Presence or absence of an outer envelope
Structure:
Capsid: protein and inner core of nucleic acid
Either DNA or RNA – not both
Might contain an envelope – if not, it is said to be naked
This is ebola
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5. Reproduction of Viruses
Viruses are microscopic pirates, they commandeer the host cells machinery
One of the portions of a naked capsid, or an envelope spike, fits like a lock and key into the host cell’s outer surface
Because of this “lock and key” fit, viruses are very specific to the cells they can infect
Antiviral medications interfere with the “lock and key mechanism
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Reproduction of Viruses

6. The Lytic Cycle Can be divided into five stages
Attachment – where the virus attaches to the outside of the host cell
Penetration – the DNA is then transferred into the host cell
Biosynthesis – begins when the virus inactivates host cell genes not necessary for viral reproduction
Maturation – Viral DNA and capsids assemble and produce several hundred viral particles
Release – Lysosome disrupts, or lyses the cell wall and the virus is released
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7. Lysogenic Cycle
An infecting virus does not immediately proliferate (reproduce), meaning the phage is latent
Following attachment and penetration, integration occurs, viral DNA becomes incorporated into host DNA with no destruction
Viral DNA is replicated with the host DNA into all subsequent cells
Certain environmental factors can trigger the lysogenic cycle
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8. Examples of Lysogenic Viruses
Diphtheria – once the lysogenic cycle is begun, a toxin released by the virus damages the lining of the respiratory tract restricting breathing
Scarlet Fever – When the bacteria that causes strep throat, also carries a certain prophage, it will release a toxin that causes a widespread skin rash
HIV – a person with HIV can live for years without showing symptoms, but can still spread the virus to others
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9. Things to think about How is this virus spread?
Who is affected by viruses now?
What kinds of medical treatments were available at the time?
What was happening in the world in 1918?

10. Claim-Evidence-Reasoning
You will now do a gallery walk – you will walk from station to station with post its
At each station you will write one post it
You will include that you agree or disagree, and
your evidence as to why
Your reasoning as to why that evidence applies to this scenario
So, each post it will have three bullets – no you don’t need to include your name THIS TIME

11. Compare and contrast Viruses to Cells
Draw a Venn Diagram
Use the given vocabulary
Be concise and precise